From 579342810f5c453e91063c54ca6544300ea09090 Mon Sep 17 00:00:00 2001
From: RevoluPowered <gordon@gordonite.tech>
Date: Mon, 20 Jul 2020 17:35:34 +0100
Subject: t Add unit testing to Godot using DocTest and added to GitHub Actions
 CI

Implements exit codes into the engine so tests can return their statuses.
Ideally we don't do this, and we use FIXUP logic to 'begin' and 'end' the engine execution for tests specifically.

Since realistically we're initialising the engine here we don't want to do that, since String should not require an engine startup to test a single header.

This lowers the complexity of running the unit tests and even for
physics should be possible to implement such a fix.
---
 main/SCsub                         |    1 -
 main/main.cpp                      |  395 ++++++++----
 main/main.h                        |   17 +-
 main/tests/test_main.cpp           |  111 ++--
 main/tests/test_main.h             |    2 +-
 main/tests/test_string.cpp         | 1207 ------------------------------------
 main/tests/test_string.h           |  758 +++++++++++++++++++++-
 main/tests/test_validate_testing.h |   42 ++
 8 files changed, 1136 insertions(+), 1397 deletions(-)
 delete mode 100644 main/tests/test_string.cpp
 create mode 100644 main/tests/test_validate_testing.h

(limited to 'main')

diff --git a/main/SCsub b/main/SCsub
index 7a301b82bc..bf188d7328 100644
--- a/main/SCsub
+++ b/main/SCsub
@@ -9,7 +9,6 @@ env.main_sources = []
 
 env.add_source_files(env.main_sources, "*.cpp")
 
-
 env.Depends("#main/splash.gen.h", "#main/splash.png")
 env.CommandNoCache("#main/splash.gen.h", "#main/splash.png", run_in_subprocess(main_builders.make_splash))
 
diff --git a/main/main.cpp b/main/main.cpp
index a500e173a2..e60bdda18d 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -30,6 +30,7 @@
 
 #include "main.h"
 
+#include "core/core_string_names.h"
 #include "core/crypto/crypto.h"
 #include "core/debugger/engine_debugger.h"
 #include "core/input/input.h"
@@ -75,12 +76,14 @@
 #include "servers/xr_server.h"
 
 #ifdef TOOLS_ENABLED
+
 #include "editor/doc_data.h"
 #include "editor/doc_data_class_path.gen.h"
 #include "editor/editor_node.h"
 #include "editor/editor_settings.h"
 #include "editor/progress_dialog.h"
 #include "editor/project_manager.h"
+
 #endif
 
 /* Static members */
@@ -186,7 +189,8 @@ static String get_full_version_string() {
 // to have less code in main.cpp.
 void initialize_physics() {
 	/// 3D Physics Server
-	physics_server = PhysicsServer3DManager::new_server(ProjectSettings::get_singleton()->get(PhysicsServer3DManager::setting_property_name));
+	physics_server = PhysicsServer3DManager::new_server(
+			ProjectSettings::get_singleton()->get(PhysicsServer3DManager::setting_property_name));
 	if (!physics_server) {
 		// Physics server not found, Use the default physics
 		physics_server = PhysicsServer3DManager::new_default_server();
@@ -195,7 +199,8 @@ void initialize_physics() {
 	physics_server->init();
 
 	/// 2D Physics server
-	physics_2d_server = PhysicsServer2DManager::new_server(ProjectSettings::get_singleton()->get(PhysicsServer2DManager::setting_property_name));
+	physics_2d_server = PhysicsServer2DManager::new_server(
+			ProjectSettings::get_singleton()->get(PhysicsServer2DManager::setting_property_name));
 	if (!physics_2d_server) {
 		// Physics server not found, Use the default physics
 		physics_2d_server = PhysicsServer2DManager::new_default_server();
@@ -254,20 +259,25 @@ void Main::print_help(const char *p_binary) {
 	OS::get_singleton()->print("  -h, --help                       Display this help message.\n");
 	OS::get_singleton()->print("  --version                        Display the version string.\n");
 	OS::get_singleton()->print("  -v, --verbose                    Use verbose stdout mode.\n");
-	OS::get_singleton()->print("  --quiet                          Quiet mode, silences stdout messages. Errors are still displayed.\n");
+	OS::get_singleton()->print(
+			"  --quiet                          Quiet mode, silences stdout messages. Errors are still displayed.\n");
 	OS::get_singleton()->print("\n");
 
 	OS::get_singleton()->print("Run options:\n");
 #ifdef TOOLS_ENABLED
 	OS::get_singleton()->print("  -e, --editor                     Start the editor instead of running the scene.\n");
-	OS::get_singleton()->print("  -p, --project-manager            Start the project manager, even if a project is auto-detected.\n");
+	OS::get_singleton()->print(
+			"  -p, --project-manager            Start the project manager, even if a project is auto-detected.\n");
 #endif
 	OS::get_singleton()->print("  -q, --quit                       Quit after the first iteration.\n");
-	OS::get_singleton()->print("  -l, --language <locale>          Use a specific locale (<locale> being a two-letter code).\n");
-	OS::get_singleton()->print("  --path <directory>               Path to a project (<directory> must contain a 'project.godot' file).\n");
+	OS::get_singleton()->print(
+			"  -l, --language <locale>          Use a specific locale (<locale> being a two-letter code).\n");
+	OS::get_singleton()->print(
+			"  --path <directory>               Path to a project (<directory> must contain a 'project.godot' file).\n");
 	OS::get_singleton()->print("  -u, --upwards                    Scan folders upwards for project.godot file.\n");
 	OS::get_singleton()->print("  --main-pack <file>               Path to a pack (.pck) file to load.\n");
-	OS::get_singleton()->print("  --render-thread <mode>           Render thread mode ('unsafe', 'safe', 'separate').\n");
+	OS::get_singleton()->print(
+			"  --render-thread <mode>           Render thread mode ('unsafe', 'safe', 'separate').\n");
 	OS::get_singleton()->print("  --remote-fs <address>            Remote filesystem (<host/IP>[:<port>] address).\n");
 	OS::get_singleton()->print("  --remote-fs-password <password>  Password for remote filesystem.\n");
 
@@ -308,9 +318,12 @@ void Main::print_help(const char *p_binary) {
 	OS::get_singleton()->print("  --resolution <W>x<H>             Request window resolution.\n");
 	OS::get_singleton()->print("  --position <X>,<Y>               Request window position.\n");
 	OS::get_singleton()->print("  --low-dpi                        Force low-DPI mode (macOS and Windows only).\n");
-	OS::get_singleton()->print("  --no-window                      Disable window creation (Windows only). Useful together with --script.\n");
-	OS::get_singleton()->print("  --enable-vsync-via-compositor    When vsync is enabled, vsync via the OS' window compositor (Windows only).\n");
-	OS::get_singleton()->print("  --disable-vsync-via-compositor   Disable vsync via the OS' window compositor (Windows only).\n");
+	OS::get_singleton()->print(
+			"  --no-window                      Disable window creation (Windows only). Useful together with --script.\n");
+	OS::get_singleton()->print(
+			"  --enable-vsync-via-compositor    When vsync is enabled, vsync via the OS' window compositor (Windows only).\n");
+	OS::get_singleton()->print(
+			"  --disable-vsync-via-compositor   Disable vsync via the OS' window compositor (Windows only).\n");
 	OS::get_singleton()->print("  --single-window                  Use a single window (no separate subwindows).\n");
 	OS::get_singleton()->print("  --tablet-driver                  Tablet input driver (");
 	for (int i = 0; i < OS::get_singleton()->get_tablet_driver_count(); i++) {
@@ -324,35 +337,51 @@ void Main::print_help(const char *p_binary) {
 
 	OS::get_singleton()->print("Debug options:\n");
 	OS::get_singleton()->print("  -d, --debug                      Debug (local stdout debugger).\n");
-	OS::get_singleton()->print("  -b, --breakpoints                Breakpoint list as source::line comma-separated pairs, no spaces (use %%20 instead).\n");
+	OS::get_singleton()->print(
+			"  -b, --breakpoints                Breakpoint list as source::line comma-separated pairs, no spaces (use %%20 instead).\n");
 	OS::get_singleton()->print("  --profiling                      Enable profiling in the script debugger.\n");
-	OS::get_singleton()->print("  --gpu-abort                      Abort on GPU errors (usually validation layer errors), may help see the problem if your system freezes.\n");
-	OS::get_singleton()->print("  --remote-debug <uri>             Remote debug (<protocol>://<host/IP>[:<port>], e.g. tcp://127.0.0.1:6007).\n");
+	OS::get_singleton()->print(
+			"  --gpu-abort                      Abort on GPU errors (usually validation layer errors), may help see the problem if your system freezes.\n");
+	OS::get_singleton()->print(
+			"  --remote-debug <uri>             Remote debug (<protocol>://<host/IP>[:<port>], e.g. tcp://127.0.0.1:6007).\n");
 #if defined(DEBUG_ENABLED) && !defined(SERVER_ENABLED)
 	OS::get_singleton()->print("  --debug-collisions               Show collision shapes when running the scene.\n");
 	OS::get_singleton()->print("  --debug-navigation               Show navigation polygons when running the scene.\n");
 #endif
-	OS::get_singleton()->print("  --frame-delay <ms>               Simulate high CPU load (delay each frame by <ms> milliseconds).\n");
-	OS::get_singleton()->print("  --time-scale <scale>             Force time scale (higher values are faster, 1.0 is normal speed).\n");
-	OS::get_singleton()->print("  --disable-render-loop            Disable render loop so rendering only occurs when called explicitly from script.\n");
-	OS::get_singleton()->print("  --disable-crash-handler          Disable crash handler when supported by the platform code.\n");
-	OS::get_singleton()->print("  --fixed-fps <fps>                Force a fixed number of frames per second. This setting disables real-time synchronization.\n");
+	OS::get_singleton()->print(
+			"  --frame-delay <ms>               Simulate high CPU load (delay each frame by <ms> milliseconds).\n");
+	OS::get_singleton()->print(
+			"  --time-scale <scale>             Force time scale (higher values are faster, 1.0 is normal speed).\n");
+	OS::get_singleton()->print(
+			"  --disable-render-loop            Disable render loop so rendering only occurs when called explicitly from script.\n");
+	OS::get_singleton()->print(
+			"  --disable-crash-handler          Disable crash handler when supported by the platform code.\n");
+	OS::get_singleton()->print(
+			"  --fixed-fps <fps>                Force a fixed number of frames per second. This setting disables real-time synchronization.\n");
 	OS::get_singleton()->print("  --print-fps                      Print the frames per second to the stdout.\n");
 	OS::get_singleton()->print("\n");
 
 	OS::get_singleton()->print("Standalone tools:\n");
 	OS::get_singleton()->print("  -s, --script <script>            Run a script.\n");
-	OS::get_singleton()->print("  --check-only                     Only parse for errors and quit (use with --script).\n");
+	OS::get_singleton()->print(
+			"  --check-only                     Only parse for errors and quit (use with --script).\n");
 #ifdef TOOLS_ENABLED
-	OS::get_singleton()->print("  --export <preset> <path>         Export the project using the given preset and matching release template. The preset name should match one defined in export_presets.cfg.\n");
-	OS::get_singleton()->print("                                   <path> should be absolute or relative to the project directory, and include the filename for the binary (e.g. 'builds/game.exe'). The target directory should exist.\n");
+	OS::get_singleton()->print(
+			"  --export <preset> <path>         Export the project using the given preset and matching release template. The preset name should match one defined in export_presets.cfg.\n");
+	OS::get_singleton()->print(
+			"                                   <path> should be absolute or relative to the project directory, and include the filename for the binary (e.g. 'builds/game.exe'). The target directory should exist.\n");
 	OS::get_singleton()->print("  --export-debug <preset> <path>   Same as --export, but using the debug template.\n");
-	OS::get_singleton()->print("  --export-pack <preset> <path>    Same as --export, but only export the game pack for the given preset. The <path> extension determines whether it will be in PCK or ZIP format.\n");
-	OS::get_singleton()->print("  --doctool <path>                 Dump the engine API reference to the given <path> in XML format, merging if existing files are found.\n");
-	OS::get_singleton()->print("  --no-docbase                     Disallow dumping the base types (used with --doctool).\n");
-	OS::get_singleton()->print("  --build-solutions                Build the scripting solutions (e.g. for C# projects). Implies --editor and requires a valid project to edit.\n");
+	OS::get_singleton()->print(
+			"  --export-pack <preset> <path>    Same as --export, but only export the game pack for the given preset. The <path> extension determines whether it will be in PCK or ZIP format.\n");
+	OS::get_singleton()->print(
+			"  --doctool <path>                 Dump the engine API reference to the given <path> in XML format, merging if existing files are found.\n");
+	OS::get_singleton()->print(
+			"  --no-docbase                     Disallow dumping the base types (used with --doctool).\n");
+	OS::get_singleton()->print(
+			"  --build-solutions                Build the scripting solutions (e.g. for C# projects). Implies --editor and requires a valid project to edit.\n");
 #ifdef DEBUG_METHODS_ENABLED
-	OS::get_singleton()->print("  --gdnative-generate-json-api     Generate JSON dump of the Godot API for GDNative bindings.\n");
+	OS::get_singleton()->print(
+			"  --gdnative-generate-json-api     Generate JSON dump of the Godot API for GDNative bindings.\n");
 #endif
 	OS::get_singleton()->print("  --test <test>                    Run a unit test [");
 	const char **test_names = tests_get_names();
@@ -366,6 +395,23 @@ void Main::print_help(const char *p_binary) {
 #endif
 }
 
+int Main::test_entrypoint(int argc, char *argv[], bool &tests_need_run) {
+#ifdef TOOLS_ENABLED // templates can't run unit test tool
+	OS::get_singleton()->initialize();
+	StringName::setup();
+	for (int x = 0; x < argc; x++) {
+		if (strncmp(argv[x], "--test", 6)) {
+			tests_need_run = true;
+			return test_main(argc, argv);
+		}
+	}
+	StringName::cleanup();
+	OS::get_singleton()->finalize();
+#endif
+	tests_need_run = false;
+	return 0;
+}
+
 /* Engine initialization
  *
  * Consists of several methods that are called by each platform's specific main(argc, argv).
@@ -418,7 +464,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	ClassDB::register_class<Performance>();
 	engine->add_singleton(Engine::Singleton("Performance", performance));
 
-	GLOBAL_DEF("debug/settings/crash_handler/message", String("Please include this when reporting the bug on https://github.com/godotengine/godot/issues"));
+	GLOBAL_DEF("debug/settings/crash_handler/message",
+			String("Please include this when reporting the bug on https://github.com/godotengine/godot/issues"));
 
 	MAIN_PRINT("Main: Parse CMDLine");
 
@@ -523,7 +570,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 				}
 
 				if (!found) {
-					OS::get_singleton()->print("Unknown audio driver '%s', aborting.\nValid options are ", audio_driver.utf8().get_data());
+					OS::get_singleton()->print("Unknown audio driver '%s', aborting.\nValid options are ",
+							audio_driver.utf8().get_data());
 
 					for (int i = 0; i < AudioDriverManager::get_driver_count(); i++) {
 						if (i == AudioDriverManager::get_driver_count() - 1) {
@@ -559,7 +607,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 				}
 
 				if (!found) {
-					OS::get_singleton()->print("Unknown display driver '%s', aborting.\nValid options are ", display_driver.utf8().get_data());
+					OS::get_singleton()->print("Unknown display driver '%s', aborting.\nValid options are ",
+							display_driver.utf8().get_data());
 
 					for (int i = 0; i < DisplayServer::get_create_function_count(); i++) {
 						if (i == DisplayServer::get_create_function_count() - 1) {
@@ -607,7 +656,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 				}
 
 				if (!found) {
-					OS::get_singleton()->print("Unknown tablet driver '%s', aborting.\n", tablet_driver.utf8().get_data());
+					OS::get_singleton()->print("Unknown tablet driver '%s', aborting.\n",
+							tablet_driver.utf8().get_data());
 					goto error;
 				}
 
@@ -629,7 +679,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 
 				if (vm.find("x") == -1) { // invalid parameter format
 
-					OS::get_singleton()->print("Invalid resolution '%s', it should be e.g. '1280x720'.\n", vm.utf8().get_data());
+					OS::get_singleton()->print("Invalid resolution '%s', it should be e.g. '1280x720'.\n",
+							vm.utf8().get_data());
 					goto error;
 				}
 
@@ -637,7 +688,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 				int h = vm.get_slice("x", 1).to_int();
 
 				if (w <= 0 || h <= 0) {
-					OS::get_singleton()->print("Invalid resolution '%s', width and height must be above 0.\n", vm.utf8().get_data());
+					OS::get_singleton()->print("Invalid resolution '%s', width and height must be above 0.\n",
+							vm.utf8().get_data());
 					goto error;
 				}
 
@@ -658,7 +710,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 
 				if (vm.find(",") == -1) { // invalid parameter format
 
-					OS::get_singleton()->print("Invalid position '%s', it should be e.g. '80,128'.\n", vm.utf8().get_data());
+					OS::get_singleton()->print("Invalid position '%s', it should be e.g. '80,128'.\n",
+							vm.utf8().get_data());
 					goto error;
 				}
 
@@ -754,7 +807,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 			// We still pass it to the main arguments since the argument handling itself is not done in this function
 			main_args.push_back(I->get());
 #endif
-		} else if (I->get() == "--export" || I->get() == "--export-debug" || I->get() == "--export-pack") { // Export project
+		} else if (I->get() == "--export" || I->get() == "--export-debug" ||
+				   I->get() == "--export-pack") { // Export project
 
 			editor = true;
 			main_args.push_back(I->get());
@@ -847,7 +901,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 			if (I->next()) {
 				debug_uri = I->next()->get();
 				if (debug_uri.find("://") == -1) { // wrong address
-					OS::get_singleton()->print("Invalid debug host address, it should be of the form <protocol>://<host/IP>:<port>.\n");
+					OS::get_singleton()->print(
+							"Invalid debug host address, it should be of the form <protocol>://<host/IP>:<port>.\n");
 					goto error;
 				}
 				N = I->next()->next();
@@ -888,7 +943,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 
 #ifdef TOOLS_ENABLED
 	if (editor && project_manager) {
-		OS::get_singleton()->print("Error: Command line arguments implied opening both editor and project manager, which is not possible. Aborting.\n");
+		OS::get_singleton()->print(
+				"Error: Command line arguments implied opening both editor and project manager, which is not possible. Aborting.\n");
 		goto error;
 	}
 #endif
@@ -935,15 +991,35 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	OS::get_singleton()->ensure_user_data_dir();
 
 	GLOBAL_DEF("memory/limits/multithreaded_server/rid_pool_prealloc", 60);
-	ProjectSettings::get_singleton()->set_custom_property_info("memory/limits/multithreaded_server/rid_pool_prealloc", PropertyInfo(Variant::INT, "memory/limits/multithreaded_server/rid_pool_prealloc", PROPERTY_HINT_RANGE, "0,500,1")); // No negative and limit to 500 due to crashes
+	ProjectSettings::get_singleton()->set_custom_property_info("memory/limits/multithreaded_server/rid_pool_prealloc",
+			PropertyInfo(Variant::INT,
+					"memory/limits/multithreaded_server/rid_pool_prealloc",
+					PROPERTY_HINT_RANGE,
+					"0,500,1")); // No negative and limit to 500 due to crashes
 	GLOBAL_DEF("network/limits/debugger/max_chars_per_second", 32768);
-	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_chars_per_second", PropertyInfo(Variant::INT, "network/limits/debugger/max_chars_per_second", PROPERTY_HINT_RANGE, "0, 4096, 1, or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_chars_per_second",
+			PropertyInfo(Variant::INT,
+					"network/limits/debugger/max_chars_per_second",
+					PROPERTY_HINT_RANGE,
+					"0, 4096, 1, or_greater"));
 	GLOBAL_DEF("network/limits/debugger/max_queued_messages", 2048);
-	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_queued_messages", PropertyInfo(Variant::INT, "network/limits/debugger/max_queued_messages", PROPERTY_HINT_RANGE, "0, 8192, 1, or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_queued_messages",
+			PropertyInfo(Variant::INT,
+					"network/limits/debugger/max_queued_messages",
+					PROPERTY_HINT_RANGE,
+					"0, 8192, 1, or_greater"));
 	GLOBAL_DEF("network/limits/debugger/max_errors_per_second", 400);
-	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_errors_per_second", PropertyInfo(Variant::INT, "network/limits/debugger/max_errors_per_second", PROPERTY_HINT_RANGE, "0, 200, 1, or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_errors_per_second",
+			PropertyInfo(Variant::INT,
+					"network/limits/debugger/max_errors_per_second",
+					PROPERTY_HINT_RANGE,
+					"0, 200, 1, or_greater"));
 	GLOBAL_DEF("network/limits/debugger/max_warnings_per_second", 400);
-	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_warnings_per_second", PropertyInfo(Variant::INT, "network/limits/debugger/max_warnings_per_second", PROPERTY_HINT_RANGE, "0, 200, 1, or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("network/limits/debugger/max_warnings_per_second",
+			PropertyInfo(Variant::INT,
+					"network/limits/debugger/max_warnings_per_second",
+					PROPERTY_HINT_RANGE,
+					"0, 200, 1, or_greater"));
 
 	EngineDebugger::initialize(debug_uri, skip_breakpoints, breakpoints);
 
@@ -978,8 +1054,13 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	GLOBAL_DEF("logging/file_logging/enable_file_logging.pc", true);
 	GLOBAL_DEF("logging/file_logging/log_path", "user://logs/godot.log");
 	GLOBAL_DEF("logging/file_logging/max_log_files", 5);
-	ProjectSettings::get_singleton()->set_custom_property_info("logging/file_logging/max_log_files", PropertyInfo(Variant::INT, "logging/file_logging/max_log_files", PROPERTY_HINT_RANGE, "0,20,1,or_greater")); //no negative numbers
-	if (!project_manager && !editor && FileAccess::get_create_func(FileAccess::ACCESS_USERDATA) && GLOBAL_GET("logging/file_logging/enable_file_logging")) {
+	ProjectSettings::get_singleton()->set_custom_property_info("logging/file_logging/max_log_files",
+			PropertyInfo(Variant::INT,
+					"logging/file_logging/max_log_files",
+					PROPERTY_HINT_RANGE,
+					"0,20,1,or_greater")); //no negative numbers
+	if (!project_manager && !editor && FileAccess::get_create_func(FileAccess::ACCESS_USERDATA) &&
+			GLOBAL_GET("logging/file_logging/enable_file_logging")) {
 		// Don't create logs for the project manager as they would be written to
 		// the current working directory, which is inconvenient.
 		String base_path = GLOBAL_GET("logging/file_logging/log_path");
@@ -1020,7 +1101,10 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	OS::get_singleton()->set_cmdline(execpath, main_args);
 
 	GLOBAL_DEF("rendering/quality/driver/driver_name", "Vulkan");
-	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/driver/driver_name", PropertyInfo(Variant::STRING, "rendering/quality/driver/driver_name", PROPERTY_HINT_ENUM, "Vulkan,GLES2"));
+	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/driver/driver_name",
+			PropertyInfo(Variant::STRING,
+					"rendering/quality/driver/driver_name",
+					PROPERTY_HINT_ENUM, "Vulkan,GLES2"));
 	if (display_driver == "") {
 		display_driver = GLOBAL_GET("rendering/quality/driver/driver_name");
 	}
@@ -1029,24 +1113,39 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	GLOBAL_DEF("rendering/quality/2d/gles2_use_nvidia_rect_flicker_workaround", false);
 
 	GLOBAL_DEF("display/window/size/width", 1024);
-	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/width", PropertyInfo(Variant::INT, "display/window/size/width", PROPERTY_HINT_RANGE, "0,7680,or_greater")); // 8K resolution
+	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/width",
+			PropertyInfo(Variant::INT, "display/window/size/width",
+					PROPERTY_HINT_RANGE,
+					"0,7680,or_greater")); // 8K resolution
 	GLOBAL_DEF("display/window/size/height", 600);
-	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/height", PropertyInfo(Variant::INT, "display/window/size/height", PROPERTY_HINT_RANGE, "0,4320,or_greater")); // 8K resolution
+	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/height",
+			PropertyInfo(Variant::INT, "display/window/size/height",
+					PROPERTY_HINT_RANGE,
+					"0,4320,or_greater")); // 8K resolution
 	GLOBAL_DEF("display/window/size/resizable", true);
 	GLOBAL_DEF("display/window/size/borderless", false);
 	GLOBAL_DEF("display/window/size/fullscreen", false);
 	GLOBAL_DEF("display/window/size/always_on_top", false);
 	GLOBAL_DEF("display/window/size/test_width", 0);
-	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/test_width", PropertyInfo(Variant::INT, "display/window/size/test_width", PROPERTY_HINT_RANGE, "0,7680,or_greater")); // 8K resolution
+	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/test_width",
+			PropertyInfo(Variant::INT,
+					"display/window/size/test_width",
+					PROPERTY_HINT_RANGE,
+					"0,7680,or_greater")); // 8K resolution
 	GLOBAL_DEF("display/window/size/test_height", 0);
-	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/test_height", PropertyInfo(Variant::INT, "display/window/size/test_height", PROPERTY_HINT_RANGE, "0,4320,or_greater")); // 8K resolution
+	ProjectSettings::get_singleton()->set_custom_property_info("display/window/size/test_height",
+			PropertyInfo(Variant::INT,
+					"display/window/size/test_height",
+					PROPERTY_HINT_RANGE,
+					"0,4320,or_greater")); // 8K resolution
 
 	if (use_custom_res) {
 		if (!force_res) {
 			window_size.width = GLOBAL_GET("display/window/size/width");
 			window_size.height = GLOBAL_GET("display/window/size/height");
 
-			if (globals->has_setting("display/window/size/test_width") && globals->has_setting("display/window/size/test_height")) {
+			if (globals->has_setting("display/window/size/test_width") &&
+					globals->has_setting("display/window/size/test_height")) {
 				int tw = globals->get("display/window/size/test_width");
 				if (tw > 0) {
 					window_size.width = tw;
@@ -1106,8 +1205,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	}
 
 	/* todo restore
-	OS::get_singleton()->_allow_layered = GLOBAL_DEF("display/window/per_pixel_transparency/allowed", false);
-	video_mode.layered = GLOBAL_DEF("display/window/per_pixel_transparency/enabled", false);
+    OS::get_singleton()->_allow_layered = GLOBAL_DEF("display/window/per_pixel_transparency/allowed", false);
+    video_mode.layered = GLOBAL_DEF("display/window/per_pixel_transparency/enabled", false);
 */
 	GLOBAL_DEF("rendering/quality/intended_usage/framebuffer_allocation", 2);
 	GLOBAL_DEF("rendering/quality/intended_usage/framebuffer_allocation.mobile", 3);
@@ -1180,10 +1279,15 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	}
 
 	Engine::get_singleton()->set_iterations_per_second(GLOBAL_DEF("physics/common/physics_fps", 60));
-	ProjectSettings::get_singleton()->set_custom_property_info("physics/common/physics_fps", PropertyInfo(Variant::INT, "physics/common/physics_fps", PROPERTY_HINT_RANGE, "1,120,1,or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("physics/common/physics_fps",
+			PropertyInfo(Variant::INT, "physics/common/physics_fps",
+					PROPERTY_HINT_RANGE, "1,120,1,or_greater"));
 	Engine::get_singleton()->set_physics_jitter_fix(GLOBAL_DEF("physics/common/physics_jitter_fix", 0.5));
 	Engine::get_singleton()->set_target_fps(GLOBAL_DEF("debug/settings/fps/force_fps", 0));
-	ProjectSettings::get_singleton()->set_custom_property_info("debug/settings/fps/force_fps", PropertyInfo(Variant::INT, "debug/settings/fps/force_fps", PROPERTY_HINT_RANGE, "0,120,1,or_greater"));
+	ProjectSettings::get_singleton()->set_custom_property_info("debug/settings/fps/force_fps",
+			PropertyInfo(Variant::INT,
+					"debug/settings/fps/force_fps",
+					PROPERTY_HINT_RANGE, "0,120,1,or_greater"));
 
 	GLOBAL_DEF("debug/settings/stdout/print_fps", false);
 	GLOBAL_DEF("debug/settings/stdout/verbose_stdout", false);
@@ -1194,12 +1298,21 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 
 	if (frame_delay == 0) {
 		frame_delay = GLOBAL_DEF("application/run/frame_delay_msec", 0);
-		ProjectSettings::get_singleton()->set_custom_property_info("application/run/frame_delay_msec", PropertyInfo(Variant::INT, "application/run/frame_delay_msec", PROPERTY_HINT_RANGE, "0,100,1,or_greater")); // No negative numbers
+		ProjectSettings::get_singleton()->set_custom_property_info("application/run/frame_delay_msec",
+				PropertyInfo(Variant::INT,
+						"application/run/frame_delay_msec",
+						PROPERTY_HINT_RANGE,
+						"0,100,1,or_greater")); // No negative numbers
 	}
 
 	OS::get_singleton()->set_low_processor_usage_mode(GLOBAL_DEF("application/run/low_processor_mode", false));
-	OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(GLOBAL_DEF("application/run/low_processor_mode_sleep_usec", 6900)); // Roughly 144 FPS
-	ProjectSettings::get_singleton()->set_custom_property_info("application/run/low_processor_mode_sleep_usec", PropertyInfo(Variant::INT, "application/run/low_processor_mode_sleep_usec", PROPERTY_HINT_RANGE, "0,33200,1,or_greater")); // No negative numbers
+	OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(
+			GLOBAL_DEF("application/run/low_processor_mode_sleep_usec", 6900)); // Roughly 144 FPS
+	ProjectSettings::get_singleton()->set_custom_property_info("application/run/low_processor_mode_sleep_usec",
+			PropertyInfo(Variant::INT,
+					"application/run/low_processor_mode_sleep_usec",
+					PROPERTY_HINT_RANGE,
+					"0,33200,1,or_greater")); // No negative numbers
 
 	GLOBAL_DEF("display/window/ios/hide_home_indicator", true);
 
@@ -1286,14 +1399,16 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 		String rendering_driver; // temp broken
 
 		Error err;
-		display_server = DisplayServer::create(display_driver_idx, rendering_driver, window_mode, window_flags, window_size, err);
+		display_server = DisplayServer::create(display_driver_idx, rendering_driver, window_mode, window_flags,
+				window_size, err);
 		if (err != OK) {
 			//ok i guess we can't use this display server, try other ones
 			for (int i = 0; i < DisplayServer::get_create_function_count(); i++) {
 				if (i == display_driver_idx) {
 					continue; //don't try the same twice
 				}
-				display_server = DisplayServer::create(display_driver_idx, rendering_driver, window_mode, window_flags, window_size, err);
+				display_server = DisplayServer::create(display_driver_idx, rendering_driver, window_mode, window_flags,
+						window_size, err);
 				if (err == OK) {
 					break;
 				}
@@ -1314,7 +1429,9 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 
 	rendering_server = memnew(RenderingServerRaster);
 	if (OS::get_singleton()->get_render_thread_mode() != OS::RENDER_THREAD_UNSAFE) {
-		rendering_server = memnew(RenderingServerWrapMT(rendering_server, OS::get_singleton()->get_render_thread_mode() == OS::RENDER_SEPARATE_THREAD));
+		rendering_server = memnew(RenderingServerWrapMT(rendering_server,
+				OS::get_singleton()->get_render_thread_mode() ==
+						OS::RENDER_SEPARATE_THREAD));
 	}
 
 	rendering_server->init();
@@ -1379,7 +1496,10 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 		String boot_logo_path = GLOBAL_DEF("application/boot_splash/image", String());
 		bool boot_logo_scale = GLOBAL_DEF("application/boot_splash/fullsize", true);
 		bool boot_logo_filter = GLOBAL_DEF("application/boot_splash/use_filter", true);
-		ProjectSettings::get_singleton()->set_custom_property_info("application/boot_splash/image", PropertyInfo(Variant::STRING, "application/boot_splash/image", PROPERTY_HINT_FILE, "*.png"));
+		ProjectSettings::get_singleton()->set_custom_property_info("application/boot_splash/image",
+				PropertyInfo(Variant::STRING,
+						"application/boot_splash/image",
+						PROPERTY_HINT_FILE, "*.png"));
 
 		Ref<Image> boot_logo;
 
@@ -1396,7 +1516,8 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 		Color boot_bg_color = GLOBAL_DEF("application/boot_splash/bg_color", boot_splash_bg_color);
 		if (boot_logo.is_valid()) {
 			OS::get_singleton()->_msec_splash = OS::get_singleton()->get_ticks_msec();
-			RenderingServer::get_singleton()->set_boot_image(boot_logo, boot_bg_color, boot_logo_scale, boot_logo_filter);
+			RenderingServer::get_singleton()->set_boot_image(boot_logo, boot_bg_color, boot_logo_scale,
+					boot_logo_filter);
 
 		} else {
 #ifndef NO_DEFAULT_BOOT_LOGO
@@ -1421,21 +1542,31 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 	}
 
 	MAIN_PRINT("Main: DCC");
-	RenderingServer::get_singleton()->set_default_clear_color(GLOBAL_DEF("rendering/environment/default_clear_color", Color(0.3, 0.3, 0.3)));
+	RenderingServer::get_singleton()->set_default_clear_color(
+			GLOBAL_DEF("rendering/environment/default_clear_color", Color(0.3, 0.3, 0.3)));
 	MAIN_PRINT("Main: END");
 
 	GLOBAL_DEF("application/config/icon", String());
-	ProjectSettings::get_singleton()->set_custom_property_info("application/config/icon", PropertyInfo(Variant::STRING, "application/config/icon", PROPERTY_HINT_FILE, "*.png,*.webp"));
+	ProjectSettings::get_singleton()->set_custom_property_info("application/config/icon",
+			PropertyInfo(Variant::STRING, "application/config/icon",
+					PROPERTY_HINT_FILE, "*.png,*.webp"));
 
 	GLOBAL_DEF("application/config/macos_native_icon", String());
-	ProjectSettings::get_singleton()->set_custom_property_info("application/config/macos_native_icon", PropertyInfo(Variant::STRING, "application/config/macos_native_icon", PROPERTY_HINT_FILE, "*.icns"));
+	ProjectSettings::get_singleton()->set_custom_property_info("application/config/macos_native_icon",
+			PropertyInfo(Variant::STRING,
+					"application/config/macos_native_icon",
+					PROPERTY_HINT_FILE, "*.icns"));
 
 	GLOBAL_DEF("application/config/windows_native_icon", String());
-	ProjectSettings::get_singleton()->set_custom_property_info("application/config/windows_native_icon", PropertyInfo(Variant::STRING, "application/config/windows_native_icon", PROPERTY_HINT_FILE, "*.ico"));
+	ProjectSettings::get_singleton()->set_custom_property_info("application/config/windows_native_icon",
+			PropertyInfo(Variant::STRING,
+					"application/config/windows_native_icon",
+					PROPERTY_HINT_FILE, "*.ico"));
 
 	Input *id = Input::get_singleton();
 	if (id) {
-		if (bool(GLOBAL_DEF("input_devices/pointing/emulate_touch_from_mouse", false)) && !(editor || project_manager)) {
+		if (bool(GLOBAL_DEF("input_devices/pointing/emulate_touch_from_mouse", false)) &&
+				!(editor || project_manager)) {
 			bool found_touchscreen = false;
 			for (int i = 0; i < DisplayServer::get_singleton()->get_screen_count(); i++) {
 				if (DisplayServer::get_singleton()->screen_is_touchscreen(i)) {
@@ -1460,10 +1591,14 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 	GLOBAL_DEF("display/mouse_cursor/custom_image", String());
 	GLOBAL_DEF("display/mouse_cursor/custom_image_hotspot", Vector2());
 	GLOBAL_DEF("display/mouse_cursor/tooltip_position_offset", Point2(10, 10));
-	ProjectSettings::get_singleton()->set_custom_property_info("display/mouse_cursor/custom_image", PropertyInfo(Variant::STRING, "display/mouse_cursor/custom_image", PROPERTY_HINT_FILE, "*.png,*.webp"));
+	ProjectSettings::get_singleton()->set_custom_property_info("display/mouse_cursor/custom_image",
+			PropertyInfo(Variant::STRING,
+					"display/mouse_cursor/custom_image",
+					PROPERTY_HINT_FILE, "*.png,*.webp"));
 
 	if (String(ProjectSettings::get_singleton()->get("display/mouse_cursor/custom_image")) != String()) {
-		Ref<Texture2D> cursor = ResourceLoader::load(ProjectSettings::get_singleton()->get("display/mouse_cursor/custom_image"));
+		Ref<Texture2D> cursor = ResourceLoader::load(
+				ProjectSettings::get_singleton()->get("display/mouse_cursor/custom_image"));
 		if (cursor.is_valid()) {
 			Vector2 hotspot = ProjectSettings::get_singleton()->get("display/mouse_cursor/custom_image_hotspot");
 			Input::get_singleton()->set_custom_mouse_cursor(cursor, Input::CURSOR_ARROW, hotspot);
@@ -1544,7 +1679,6 @@ bool Main::start() {
 	String positional_arg;
 	String game_path;
 	String script;
-	String test;
 	bool check_only = false;
 
 #ifdef TOOLS_ENABLED
@@ -1555,10 +1689,12 @@ bool Main::start() {
 #endif
 
 	main_timer_sync.init(OS::get_singleton()->get_ticks_usec());
-
 	List<String> args = OS::get_singleton()->get_cmdline_args();
+
+	// parameters that do not have an argument to the right
 	for (int i = 0; i < args.size(); i++) {
-		//parameters that do not have an argument to the right
+		// Doctest Unit Testing Handler
+		// Designed to override and pass arguments to the unit test handler.
 		if (args[i] == "--check-only") {
 			check_only = true;
 #ifdef TOOLS_ENABLED
@@ -1591,8 +1727,6 @@ bool Main::start() {
 			bool parsed_pair = true;
 			if (args[i] == "-s" || args[i] == "--script") {
 				script = args[i + 1];
-			} else if (args[i] == "--test") {
-				test = args[i + 1];
 #ifdef TOOLS_ENABLED
 			} else if (args[i] == "--doctool") {
 				doc_tool = args[i + 1];
@@ -1624,7 +1758,8 @@ bool Main::start() {
 	String main_loop_type;
 #ifdef TOOLS_ENABLED
 	if (doc_tool != "") {
-		Engine::get_singleton()->set_editor_hint(true); // Needed to instance editor-only classes for their default values
+		Engine::get_singleton()->set_editor_hint(
+				true); // Needed to instance editor-only classes for their default values
 
 		{
 			DirAccessRef da = DirAccess::open(doc_tool);
@@ -1694,7 +1829,7 @@ bool Main::start() {
 		print_line("Generating new docs...");
 		doc.save_classes(index_path, doc_data_classes);
 
-		return false;
+		return FAILED;
 	}
 
 	if (_export_preset != "") {
@@ -1702,7 +1837,7 @@ bool Main::start() {
 			String err = "Command line includes export parameter option, but no destination path was given.\n";
 			err += "Please specify the binary's file path to export to. Aborting export.";
 			ERR_PRINT(err);
-			return false;
+			return FAILED;
 		}
 	}
 #endif
@@ -1716,16 +1851,7 @@ bool Main::start() {
 		main_loop = memnew(SceneTree);
 	};
 
-	if (test != "") {
-#ifdef TOOLS_ENABLED
-		main_loop = test_main(test, args);
-
-		if (!main_loop) {
-			return false;
-		}
-#endif
-
-	} else if (script != "") {
+	if (script != "") {
 		Ref<Script> script_res = ResourceLoader::load(script);
 		ERR_FAIL_COND_V_MSG(script_res.is_null(), false, "Can't load script: " + script);
 
@@ -1733,7 +1859,7 @@ bool Main::start() {
 			if (!script_res->is_valid()) {
 				OS::get_singleton()->set_exit_code(1);
 			}
-			return false;
+			return FAILED;
 		}
 
 		if (script_res->can_instance()) {
@@ -1744,13 +1870,15 @@ bool Main::start() {
 				if (obj) {
 					memdelete(obj);
 				}
-				ERR_FAIL_V_MSG(false, vformat("Can't load the script \"%s\" as it doesn't inherit from SceneTree or MainLoop.", script));
+				ERR_FAIL_V_MSG(false,
+						vformat("Can't load the script \"%s\" as it doesn't inherit from SceneTree or MainLoop.",
+								script));
 			}
 
 			script_loop->set_init_script(script_res);
 			main_loop = script_loop;
 		} else {
-			return false;
+			return FAILED;
 		}
 
 	} else {
@@ -1764,7 +1892,7 @@ bool Main::start() {
 	if (!main_loop) {
 		if (!ClassDB::class_exists(main_loop_type)) {
 			DisplayServer::get_singleton()->alert("Error: MainLoop type doesn't exist: " + main_loop_type);
-			return false;
+			return FAILED;
 		} else {
 			Object *ml = ClassDB::instance(main_loop_type);
 			ERR_FAIL_COND_V_MSG(!ml, false, "Can't instance MainLoop type.");
@@ -1832,7 +1960,9 @@ bool Main::start() {
 
 						Object *obj = ClassDB::instance(ibt);
 
-						ERR_CONTINUE_MSG(obj == nullptr, "Cannot instance script for autoload, expected 'Node' inheritance, got: " + String(ibt));
+						ERR_CONTINUE_MSG(obj == nullptr,
+								"Cannot instance script for autoload, expected 'Node' inheritance, got: " +
+										String(ibt));
 
 						n = Object::cast_to<Node>(obj);
 						n->set_script(script_res);
@@ -1880,7 +2010,8 @@ bool Main::start() {
 
 			String stretch_mode = GLOBAL_DEF("display/window/stretch/mode", "disabled");
 			String stretch_aspect = GLOBAL_DEF("display/window/stretch/aspect", "ignore");
-			Size2i stretch_size = Size2(GLOBAL_DEF("display/window/size/width", 0), GLOBAL_DEF("display/window/size/height", 0));
+			Size2i stretch_size = Size2(GLOBAL_DEF("display/window/size/width", 0),
+					GLOBAL_DEF("display/window/size/height", 0));
 
 			Window::ContentScaleMode cs_sm = Window::CONTENT_SCALE_MODE_DISABLED;
 			if (stretch_mode == "canvas_items") {
@@ -1924,10 +2055,14 @@ bool Main::start() {
 			int shadow_atlas_q3_subdiv = GLOBAL_GET("rendering/quality/shadow_atlas/quadrant_3_subdiv");
 
 			sml->get_root()->set_shadow_atlas_size(shadow_atlas_size);
-			sml->get_root()->set_shadow_atlas_quadrant_subdiv(0, Viewport::ShadowAtlasQuadrantSubdiv(shadow_atlas_q0_subdiv));
-			sml->get_root()->set_shadow_atlas_quadrant_subdiv(1, Viewport::ShadowAtlasQuadrantSubdiv(shadow_atlas_q1_subdiv));
-			sml->get_root()->set_shadow_atlas_quadrant_subdiv(2, Viewport::ShadowAtlasQuadrantSubdiv(shadow_atlas_q2_subdiv));
-			sml->get_root()->set_shadow_atlas_quadrant_subdiv(3, Viewport::ShadowAtlasQuadrantSubdiv(shadow_atlas_q3_subdiv));
+			sml->get_root()->set_shadow_atlas_quadrant_subdiv(0, Viewport::ShadowAtlasQuadrantSubdiv(
+																		 shadow_atlas_q0_subdiv));
+			sml->get_root()->set_shadow_atlas_quadrant_subdiv(1, Viewport::ShadowAtlasQuadrantSubdiv(
+																		 shadow_atlas_q1_subdiv));
+			sml->get_root()->set_shadow_atlas_quadrant_subdiv(2, Viewport::ShadowAtlasQuadrantSubdiv(
+																		 shadow_atlas_q2_subdiv));
+			sml->get_root()->set_shadow_atlas_quadrant_subdiv(3, Viewport::ShadowAtlasQuadrantSubdiv(
+																		 shadow_atlas_q3_subdiv));
 
 			bool snap_controls = GLOBAL_DEF("gui/common/snap_controls_to_pixels", true);
 			sml->get_root()->set_snap_controls_to_pixels(snap_controls);
@@ -1937,30 +2072,51 @@ bool Main::start() {
 
 			int texture_filter = GLOBAL_DEF("rendering/canvas_textures/default_texture_filter", 1);
 			int texture_repeat = GLOBAL_DEF("rendering/canvas_textures/default_texture_repeat", 0);
-			sml->get_root()->set_default_canvas_item_texture_filter(Viewport::DefaultCanvasItemTextureFilter(texture_filter));
-			sml->get_root()->set_default_canvas_item_texture_repeat(Viewport::DefaultCanvasItemTextureRepeat(texture_repeat));
+			sml->get_root()->set_default_canvas_item_texture_filter(
+					Viewport::DefaultCanvasItemTextureFilter(texture_filter));
+			sml->get_root()->set_default_canvas_item_texture_repeat(
+					Viewport::DefaultCanvasItemTextureRepeat(texture_repeat));
 
 		} else {
 			GLOBAL_DEF("display/window/stretch/mode", "disabled");
-			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/mode", PropertyInfo(Variant::STRING, "display/window/stretch/mode", PROPERTY_HINT_ENUM, "disabled,canvas_items,viewport"));
+			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/mode",
+					PropertyInfo(Variant::STRING,
+							"display/window/stretch/mode",
+							PROPERTY_HINT_ENUM,
+							"disabled,canvas_items,viewport"));
 			GLOBAL_DEF("display/window/stretch/aspect", "ignore");
-			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/aspect", PropertyInfo(Variant::STRING, "display/window/stretch/aspect", PROPERTY_HINT_ENUM, "ignore,keep,keep_width,keep_height,expand"));
+			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/aspect",
+					PropertyInfo(Variant::STRING,
+							"display/window/stretch/aspect",
+							PROPERTY_HINT_ENUM,
+							"ignore,keep,keep_width,keep_height,expand"));
 			GLOBAL_DEF("display/window/stretch/shrink", 1.0);
-			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/shrink", PropertyInfo(Variant::FLOAT, "display/window/stretch/shrink", PROPERTY_HINT_RANGE, "1.0,8.0,0.1"));
+			ProjectSettings::get_singleton()->set_custom_property_info("display/window/stretch/shrink",
+					PropertyInfo(Variant::FLOAT,
+							"display/window/stretch/shrink",
+							PROPERTY_HINT_RANGE,
+							"1.0,8.0,0.1"));
 			sml->set_auto_accept_quit(GLOBAL_DEF("application/config/auto_accept_quit", true));
 			sml->set_quit_on_go_back(GLOBAL_DEF("application/config/quit_on_go_back", true));
 			GLOBAL_DEF("gui/common/snap_controls_to_pixels", true);
 			GLOBAL_DEF("rendering/quality/dynamic_fonts/use_oversampling", true);
 
 			GLOBAL_DEF("rendering/canvas_textures/default_texture_filter", 1);
-			ProjectSettings::get_singleton()->set_custom_property_info("rendering/canvas_textures/default_texture_filter", PropertyInfo(Variant::INT, "rendering/canvas_textures/default_texture_filter", PROPERTY_HINT_ENUM, "Nearest,Linear,MipmapLinear,MipmapNearest"));
+			ProjectSettings::get_singleton()->set_custom_property_info(
+					"rendering/canvas_textures/default_texture_filter",
+					PropertyInfo(Variant::INT, "rendering/canvas_textures/default_texture_filter", PROPERTY_HINT_ENUM,
+							"Nearest,Linear,MipmapLinear,MipmapNearest"));
 			GLOBAL_DEF("rendering/canvas_textures/default_texture_repeat", 0);
-			ProjectSettings::get_singleton()->set_custom_property_info("rendering/canvas_textures/default_texture_repeat", PropertyInfo(Variant::INT, "rendering/canvas_textures/default_texture_repeat", PROPERTY_HINT_ENUM, "Disable,Enable,Mirror"));
+			ProjectSettings::get_singleton()->set_custom_property_info(
+					"rendering/canvas_textures/default_texture_repeat",
+					PropertyInfo(Variant::INT, "rendering/canvas_textures/default_texture_repeat", PROPERTY_HINT_ENUM,
+							"Disable,Enable,Mirror"));
 		}
 
 #ifdef TOOLS_ENABLED
 		if (editor) {
-			bool editor_embed_subwindows = EditorSettings::get_singleton()->get_setting("interface/editor/single_window_mode");
+			bool editor_embed_subwindows = EditorSettings::get_singleton()->get_setting(
+					"interface/editor/single_window_mode");
 
 			if (editor_embed_subwindows) {
 				sml->get_root()->set_embed_subwindows_hint(true);
@@ -1973,7 +2129,8 @@ bool Main::start() {
 			local_game_path = game_path.replace("\\", "/");
 
 			if (!local_game_path.begins_with("res://")) {
-				bool absolute = (local_game_path.size() > 1) && (local_game_path[0] == '/' || local_game_path[1] == ':');
+				bool absolute =
+						(local_game_path.size() > 1) && (local_game_path[0] == '/' || local_game_path[1] == ':');
 
 				if (!absolute) {
 					if (ProjectSettings::get_singleton()->is_using_datapack()) {
@@ -1989,7 +2146,8 @@ bool Main::start() {
 						} else {
 							DirAccess *da = DirAccess::open(local_game_path.substr(0, sep));
 							if (da) {
-								local_game_path = da->get_current_dir().plus_file(local_game_path.substr(sep + 1, local_game_path.length()));
+								local_game_path = da->get_current_dir().plus_file(
+										local_game_path.substr(sep + 1, local_game_path.length()));
 								memdelete(da);
 							}
 						}
@@ -2059,7 +2217,7 @@ bool Main::start() {
 		}
 
 #ifdef TOOLS_ENABLED
-		if (project_manager || (script == "" && test == "" && game_path == "" && !editor)) {
+		if (project_manager || (script == "" && game_path == "" && !editor)) {
 			Engine::get_singleton()->set_editor_hint(true);
 			ProjectManager *pmanager = memnew(ProjectManager);
 			ProgressDialog *progress_dialog = memnew(ProgressDialog);
@@ -2072,12 +2230,16 @@ bool Main::start() {
 		if (project_manager || editor) {
 			if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_CONSOLE_WINDOW)) {
 				// Hide console window if requested (Windows-only).
-				bool hide_console = EditorSettings::get_singleton()->get_setting("interface/editor/hide_console_window");
+				bool hide_console = EditorSettings::get_singleton()->get_setting(
+						"interface/editor/hide_console_window");
 				DisplayServer::get_singleton()->console_set_visible(!hide_console);
 			}
 
 			// Load SSL Certificates from Editor Settings (or builtin)
-			Crypto::load_default_certificates(EditorSettings::get_singleton()->get_setting("network/ssl/editor_ssl_certificates").operator String());
+			Crypto::load_default_certificates(EditorSettings::get_singleton()->get_setting(
+																					 "network/ssl/editor_ssl_certificates")
+													  .
+													  operator String());
 		}
 #endif
 	}
@@ -2089,7 +2251,7 @@ bool Main::start() {
 
 	OS::get_singleton()->set_main_loop(main_loop);
 
-	return true;
+	return OK;
 }
 
 /* Main iteration
@@ -2107,6 +2269,7 @@ uint32_t Main::frames = 0;
 uint32_t Main::frame = 0;
 bool Main::force_redraw_requested = false;
 int Main::iterating = 0;
+
 bool Main::is_iterating() {
 	return iterating > 0;
 }
@@ -2182,7 +2345,8 @@ bool Main::iteration() {
 
 		message_queue->flush();
 
-		physics_process_ticks = MAX(physics_process_ticks, OS::get_singleton()->get_ticks_usec() - physics_begin); // keep the largest one for reference
+		physics_process_ticks = MAX(physics_process_ticks, OS::get_singleton()->get_ticks_usec() -
+																   physics_begin); // keep the largest one for reference
 		physics_process_max = MAX(OS::get_singleton()->get_ticks_usec() - physics_begin, physics_process_max);
 		Engine::get_singleton()->_physics_frames++;
 	}
@@ -2198,7 +2362,8 @@ bool Main::iteration() {
 
 	RenderingServer::get_singleton()->sync(); //sync if still drawing from previous frames.
 
-	if (DisplayServer::get_singleton()->can_any_window_draw() && RenderingServer::get_singleton()->is_render_loop_enabled()) {
+	if (DisplayServer::get_singleton()->can_any_window_draw() &&
+			RenderingServer::get_singleton()->is_render_loop_enabled()) {
 		if ((!force_redraw_requested) && OS::get_singleton()->is_in_low_processor_usage_mode()) {
 			if (RenderingServer::get_singleton()->has_changed()) {
 				RenderingServer::get_singleton()->draw(true, scaled_step); // flush visual commands
@@ -2260,10 +2425,12 @@ bool Main::iteration() {
 		auto_build_solutions = false;
 		// Only relevant when running the editor.
 		if (!editor) {
-			ERR_FAIL_V_MSG(true, "Command line option --build-solutions was passed, but no project is being edited. Aborting.");
+			ERR_FAIL_V_MSG(true,
+					"Command line option --build-solutions was passed, but no project is being edited. Aborting.");
 		}
 		if (!EditorNode::get_singleton()->call_build()) {
-			ERR_FAIL_V_MSG(true, "Command line option --build-solutions was passed, but the build callback failed. Aborting.");
+			ERR_FAIL_V_MSG(true,
+					"Command line option --build-solutions was passed, but the build callback failed. Aborting.");
 		}
 	}
 #endif
diff --git a/main/main.h b/main/main.h
index 308128735c..20c0bebefa 100644
--- a/main/main.h
+++ b/main/main.h
@@ -45,7 +45,7 @@ class Main {
 
 public:
 	static bool is_project_manager();
-
+	static int test_entrypoint(int argc, char *argv[], bool &tests_need_run);
 	static Error setup(const char *execpath, int argc, char *argv[], bool p_second_phase = true);
 	static Error setup2(Thread::ID p_main_tid_override = 0);
 	static bool start();
@@ -58,4 +58,19 @@ public:
 	static void cleanup();
 };
 
+// Test main override is for the testing behaviour
+#define TEST_MAIN_OVERRIDE                                         \
+	bool run_test = false;                                         \
+	int return_code = Main::test_entrypoint(argc, argv, run_test); \
+	if (run_test) {                                                \
+		return return_code;                                        \
+	}
+
+#define TEST_MAIN_PARAM_OVERRIDE(argc, argv)                       \
+	bool run_test = false;                                         \
+	int return_code = Main::test_entrypoint(argc, argv, run_test); \
+	if (run_test) {                                                \
+		return return_code;                                        \
+	}
+
 #endif // MAIN_H
diff --git a/main/tests/test_main.cpp b/main/tests/test_main.cpp
index 5ebdaf1741..91eff28f86 100644
--- a/main/tests/test_main.cpp
+++ b/main/tests/test_main.cpp
@@ -47,10 +47,14 @@
 #include "test_render.h"
 #include "test_shader_lang.h"
 #include "test_string.h"
+#include "test_validate_testing.h"
+
+#include "thirdparty/doctest/doctest.h"
 
 const char **tests_get_names() {
 	static const char *test_names[] = {
-		"string",
+		"*",
+		"all",
 		"math",
 		"basis",
 		"physics_2d",
@@ -72,75 +76,38 @@ const char **tests_get_names() {
 	return test_names;
 }
 
-MainLoop *test_main(String p_test, const List<String> &p_args) {
-	if (p_test == "string") {
-		return TestString::test();
-	}
-
-	if (p_test == "math") {
-		return TestMath::test();
-	}
-
-	if (p_test == "basis") {
-		return TestBasis::test();
-	}
-
-	if (p_test == "physics_2d") {
-		return TestPhysics2D::test();
-	}
-
-	if (p_test == "physics_3d") {
-		return TestPhysics3D::test();
-	}
-
-	if (p_test == "render") {
-		return TestRender::test();
-	}
-
-	if (p_test == "oa_hash_map") {
-		return TestOAHashMap::test();
-	}
-
-	if (p_test == "class_db") {
-		return TestClassDB::test();
-	}
-
-#ifndef _3D_DISABLED
-	if (p_test == "gui") {
-		return TestGUI::test();
-	}
-#endif
-
-	if (p_test == "shaderlang") {
-		return TestShaderLang::test();
-	}
-
-	if (p_test == "gd_tokenizer") {
-		return TestGDScript::test(TestGDScript::TEST_TOKENIZER);
-	}
-
-	if (p_test == "gd_parser") {
-		return TestGDScript::test(TestGDScript::TEST_PARSER);
-	}
-
-	if (p_test == "gd_compiler") {
-		return TestGDScript::test(TestGDScript::TEST_COMPILER);
-	}
-
-	if (p_test == "gd_bytecode") {
-		return TestGDScript::test(TestGDScript::TEST_BYTECODE);
-	}
-
-	if (p_test == "ordered_hash_map") {
-		return TestOrderedHashMap::test();
-	}
-
-	if (p_test == "astar") {
-		return TestAStar::test();
-	}
-
-	print_line("Unknown test: " + p_test);
-	return nullptr;
+int test_main(int argc, char *argv[]) {
+	// doctest runner for when legacy unit tests are no  found
+	doctest::Context test_context;
+	List<String> valid_arguments;
+
+	// clean arguments of --test from the args
+	int argument_count = 0;
+	for (int x = 0; x < argc; x++) {
+		if (strncmp(argv[x], "--test", 6) != 0) {
+			valid_arguments.push_back(String(argv[x]));
+			argument_count++;
+		}
+	}
+
+	// convert godot command line arguments back to standard arguments.
+	char **args = new char *[valid_arguments.size()];
+	for (int x = 0; x < valid_arguments.size(); x++) {
+		// operation to convert godot string to non wchar string
+		const char *str = valid_arguments[x].utf8().ptr();
+		// allocate the string copy
+		args[x] = new char[strlen(str) + 1];
+		// copy this into memory
+		std::memcpy(args[x], str, strlen(str) + 1);
+	}
+
+	test_context.applyCommandLine(valid_arguments.size(), args);
+
+	test_context.setOption("order-by", "name");
+	test_context.setOption("abort-after", 5);
+	test_context.setOption("no-breaks", true);
+	delete[] args;
+	return test_context.run();
 }
 
 #else
@@ -153,8 +120,8 @@ const char **tests_get_names() {
 	return test_names;
 }
 
-MainLoop *test_main(String p_test, const List<String> &p_args) {
-	return nullptr;
+int test_main(int argc, char *argv[]) {
+	return 0;
 }
 
 #endif
diff --git a/main/tests/test_main.h b/main/tests/test_main.h
index bdb1668d21..8273b74eac 100644
--- a/main/tests/test_main.h
+++ b/main/tests/test_main.h
@@ -36,6 +36,6 @@
 #include "core/ustring.h"
 
 const char **tests_get_names();
-MainLoop *test_main(String p_test, const List<String> &p_args);
+int test_main(int argc, char *argv[]);
 
 #endif // TEST_MAIN_H
diff --git a/main/tests/test_string.cpp b/main/tests/test_string.cpp
deleted file mode 100644
index 73d59b0088..0000000000
--- a/main/tests/test_string.cpp
+++ /dev/null
@@ -1,1207 +0,0 @@
-/*************************************************************************/
-/*  test_string.cpp                                                      */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#include "test_string.h"
-
-#include "core/io/ip_address.h"
-#include "core/os/os.h"
-#include "core/ustring.h"
-
-#include "modules/modules_enabled.gen.h"
-#ifdef MODULE_REGEX_ENABLED
-#include "modules/regex/regex.h"
-#endif
-
-#include <stdio.h>
-#include <wchar.h>
-
-namespace TestString {
-
-bool test_1() {
-	OS::get_singleton()->print("\n\nTest 1: Assign from cstr\n");
-
-	String s = "Hello";
-
-	OS::get_singleton()->print("\tExpected: Hello\n");
-	OS::get_singleton()->print("\tResulted: %ls\n", s.c_str());
-
-	return (wcscmp(s.c_str(), L"Hello") == 0);
-}
-
-bool test_2() {
-	OS::get_singleton()->print("\n\nTest 2: Assign from string (operator=)\n");
-
-	String s = "Dolly";
-	const String &t = s;
-
-	OS::get_singleton()->print("\tExpected: Dolly\n");
-	OS::get_singleton()->print("\tResulted: %ls\n", t.c_str());
-
-	return (wcscmp(t.c_str(), L"Dolly") == 0);
-}
-
-bool test_3() {
-	OS::get_singleton()->print("\n\nTest 3: Assign from c-string (copycon)\n");
-
-	String s("Sheep");
-	const String &t(s);
-
-	OS::get_singleton()->print("\tExpected: Sheep\n");
-	OS::get_singleton()->print("\tResulted: %ls\n", t.c_str());
-
-	return (wcscmp(t.c_str(), L"Sheep") == 0);
-}
-
-bool test_4() {
-	OS::get_singleton()->print("\n\nTest 4: Assign from c-widechar (operator=)\n");
-
-	String s(L"Give me");
-
-	OS::get_singleton()->print("\tExpected: Give me\n");
-	OS::get_singleton()->print("\tResulted: %ls\n", s.c_str());
-
-	return (wcscmp(s.c_str(), L"Give me") == 0);
-}
-
-bool test_5() {
-	OS::get_singleton()->print("\n\nTest 5: Assign from c-widechar (copycon)\n");
-
-	String s(L"Wool");
-
-	OS::get_singleton()->print("\tExpected: Wool\n");
-	OS::get_singleton()->print("\tResulted: %ls\n", s.c_str());
-
-	return (wcscmp(s.c_str(), L"Wool") == 0);
-}
-
-bool test_6() {
-	OS::get_singleton()->print("\n\nTest 6: comparisons (equal)\n");
-
-	String s = "Test Compare";
-
-	OS::get_singleton()->print("\tComparing to \"Test Compare\"\n");
-
-	if (!(s == "Test Compare")) {
-		return false;
-	}
-
-	if (!(s == L"Test Compare")) {
-		return false;
-	}
-
-	if (!(s == String("Test Compare"))) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_7() {
-	OS::get_singleton()->print("\n\nTest 7: comparisons (unequal)\n");
-
-	String s = "Test Compare";
-
-	OS::get_singleton()->print("\tComparing to \"Test Compare\"\n");
-
-	if (!(s != "Peanut")) {
-		return false;
-	}
-
-	if (!(s != L"Coconut")) {
-		return false;
-	}
-
-	if (!(s != String("Butter"))) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_8() {
-	OS::get_singleton()->print("\n\nTest 8: comparisons (operator<)\n");
-
-	String s = "Bees";
-
-	OS::get_singleton()->print("\tComparing to \"Bees\"\n");
-
-	if (!(s < "Elephant")) {
-		return false;
-	}
-
-	if (s < L"Amber") {
-		return false;
-	}
-
-	if (s < String("Beatrix")) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_9() {
-	OS::get_singleton()->print("\n\nTest 9: Concatenation\n");
-
-	String s;
-
-	s += "Have";
-	s += ' ';
-	s += 'a';
-	s += String(" ");
-	s = s + L"Nice";
-	s = s + " ";
-	s = s + String("Day");
-
-	OS::get_singleton()->print("\tComparing to \"Have a Nice Day\"\n");
-
-	return (s == "Have a Nice Day");
-}
-
-bool test_10() {
-	OS::get_singleton()->print("\n\nTest 10: Misc funcs (size/length/empty/etc)\n");
-
-	if (!String("").empty()) {
-		return false;
-	}
-
-	if (String("Mellon").size() != 7) {
-		return false;
-	}
-
-	if (String("Oranges").length() != 7) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_11() {
-	OS::get_singleton()->print("\n\nTest 11: Operator[]\n");
-
-	String a = "Kugar Sane";
-
-	a[0] = 'S';
-	a[6] = 'C';
-
-	if (a != "Sugar Cane") {
-		return false;
-	}
-
-	if (a[1] != 'u') {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_12() {
-	OS::get_singleton()->print("\n\nTest 12: case functions\n");
-
-	String a = "MoMoNgA";
-
-	if (a.to_upper() != "MOMONGA") {
-		return false;
-	}
-
-	if (a.nocasecmp_to("momonga") != 0) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_13() {
-	OS::get_singleton()->print("\n\nTest 13: UTF8\n");
-
-	/* how can i embed UTF in here? */
-
-	static const CharType ustr[] = { 0x304A, 0x360F, 0x3088, 0x3046, 0 };
-	//static const wchar_t ustr[] = { 'P', 0xCE, 'p',0xD3, 0 };
-	String s = ustr;
-
-	OS::get_singleton()->print("\tUnicode: %ls\n", ustr);
-	s.parse_utf8(s.utf8().get_data());
-	OS::get_singleton()->print("\tConvert/Parse UTF8: %ls\n", s.c_str());
-
-	return (s == ustr);
-}
-
-bool test_14() {
-	OS::get_singleton()->print("\n\nTest 14: ASCII\n");
-
-	String s = L"Primero Leche";
-	OS::get_singleton()->print("\tAscii: %s\n", s.ascii().get_data());
-
-	String t = s.ascii().get_data();
-	return (s == t);
-}
-
-bool test_15() {
-	OS::get_singleton()->print("\n\nTest 15: substr\n");
-
-	String s = "Killer Baby";
-	OS::get_singleton()->print("\tsubstr(3,4) of \"%ls\" is \"%ls\"\n", s.c_str(), s.substr(3, 4).c_str());
-
-	return (s.substr(3, 4) == "ler ");
-}
-
-bool test_16() {
-	OS::get_singleton()->print("\n\nTest 16: find\n");
-
-	String s = "Pretty Woman";
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	OS::get_singleton()->print("\t\"tty\" is at %i pos.\n", s.find("tty"));
-	OS::get_singleton()->print("\t\"Revenge of the Monster Truck\" is at %i pos.\n", s.find("Revenge of the Monster Truck"));
-
-	if (s.find("tty") != 3) {
-		return false;
-	}
-
-	if (s.find("Revenge of the Monster Truck") != -1) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_17() {
-	OS::get_singleton()->print("\n\nTest 17: find no case\n");
-
-	String s = "Pretty Whale";
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	OS::get_singleton()->print("\t\"WHA\" is at %i pos.\n", s.findn("WHA"));
-	OS::get_singleton()->print("\t\"Revenge of the Monster SawFish\" is at %i pos.\n", s.findn("Revenge of the Monster Truck"));
-
-	if (s.findn("WHA") != 7) {
-		return false;
-	}
-
-	if (s.findn("Revenge of the Monster SawFish") != -1) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_18() {
-	OS::get_singleton()->print("\n\nTest 18: find no case\n");
-
-	String s = "Pretty Whale";
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	OS::get_singleton()->print("\t\"WHA\" is at %i pos.\n", s.findn("WHA"));
-	OS::get_singleton()->print("\t\"Revenge of the Monster SawFish\" is at %i pos.\n", s.findn("Revenge of the Monster Truck"));
-
-	if (s.findn("WHA") != 7) {
-		return false;
-	}
-
-	if (s.findn("Revenge of the Monster SawFish") != -1) {
-		return false;
-	}
-
-	return true;
-}
-
-bool test_19() {
-	OS::get_singleton()->print("\n\nTest 19: Search & replace\n");
-
-	String s = "Happy Birthday, Anna!";
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-
-	s = s.replace("Birthday", "Halloween");
-	OS::get_singleton()->print("\tReplaced Birthday/Halloween: %ls.\n", s.c_str());
-
-	return (s == "Happy Halloween, Anna!");
-}
-
-bool test_20() {
-	OS::get_singleton()->print("\n\nTest 20: Insertion\n");
-
-	String s = "Who is Frederic?";
-
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	s = s.insert(s.find("?"), " Chopin");
-	OS::get_singleton()->print("\tInserted Chopin: %ls.\n", s.c_str());
-
-	return (s == "Who is Frederic Chopin?");
-}
-
-bool test_21() {
-	OS::get_singleton()->print("\n\nTest 21: Number -> String\n");
-
-	OS::get_singleton()->print("\tPi is %f\n", 33.141593);
-	OS::get_singleton()->print("\tPi String is %ls\n", String::num(3.141593).c_str());
-
-	return String::num(3.141593) == "3.141593";
-}
-
-bool test_22() {
-	OS::get_singleton()->print("\n\nTest 22: String -> Int\n");
-
-	static const char *nums[4] = { "1237461283", "- 22", "0", " - 1123412" };
-	static const int num[4] = { 1237461283, -22, 0, -1123412 };
-
-	for (int i = 0; i < 4; i++) {
-#ifdef __MINGW32__ // MinGW can't handle normal format specifiers for some reason. So we need special code just for MinGW.
-		OS::get_singleton()->print("\tString: \"%s\" as Int is %I64i\n", nums[i], (long long)(String(nums[i]).to_int()));
-#else
-		OS::get_singleton()->print("\tString: \"%s\" as Int is %lli\n", nums[i], (long long)(String(nums[i]).to_int()));
-#endif
-		if (String(nums[i]).to_int() != num[i]) {
-			return false;
-		}
-	}
-
-	return true;
-}
-
-bool test_23() {
-	OS::get_singleton()->print("\n\nTest 23: String -> Float\n");
-
-	static const char *nums[4] = { "-12348298412.2", "0.05", "2.0002", " -0.0001" };
-	static const double num[4] = { -12348298412.2, 0.05, 2.0002, -0.0001 };
-
-	for (int i = 0; i < 4; i++) {
-		OS::get_singleton()->print("\tString: \"%s\" as Float is %f\n", nums[i], String(nums[i]).to_double());
-
-		if (ABS(String(nums[i]).to_double() - num[i]) > 0.00001) {
-			return false;
-		}
-	}
-
-	return true;
-}
-
-bool test_24() {
-	OS::get_singleton()->print("\n\nTest 24: Slicing\n");
-
-	String s = "Mars,Jupiter,Saturn,Uranus";
-
-	const char *slices[4] = { "Mars", "Jupiter", "Saturn", "Uranus" };
-
-	OS::get_singleton()->print("\tSlicing \"%ls\" by \"%s\"..\n", s.c_str(), ",");
-
-	for (int i = 0; i < s.get_slice_count(","); i++) {
-		OS::get_singleton()->print("\t\t%i- %ls\n", i + 1, s.get_slice(",", i).c_str());
-
-		if (s.get_slice(",", i) != slices[i]) {
-			return false;
-		}
-	}
-
-	return true;
-}
-
-bool test_25() {
-	OS::get_singleton()->print("\n\nTest 25: Erasing\n");
-
-	String s = "Josephine is such a cute girl!";
-
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	OS::get_singleton()->print("\tRemoving \"cute\"\n");
-
-	s.erase(s.find("cute "), String("cute ").length());
-	OS::get_singleton()->print("\tResult: %ls\n", s.c_str());
-
-	return (s == "Josephine is such a girl!");
-}
-
-bool test_26() {
-	OS::get_singleton()->print("\n\nTest 26: RegEx substitution\n");
-
-#ifndef MODULE_REGEX_ENABLED
-	OS::get_singleton()->print("\tRegEx module disabled, can't run test.");
-	return false;
-#else
-	String s = "Double all the vowels.";
-
-	OS::get_singleton()->print("\tString: %ls\n", s.c_str());
-	OS::get_singleton()->print("\tRepeating instances of 'aeiou' once\n");
-
-	RegEx re("(?<vowel>[aeiou])");
-	s = re.sub(s, "$0$vowel", true);
-
-	OS::get_singleton()->print("\tResult: %ls\n", s.c_str());
-
-	return (s == "Doouublee aall thee vooweels.");
-#endif
-}
-
-struct test_27_data {
-	char const *data;
-	char const *begin;
-	bool expected;
-};
-
-bool test_27() {
-	OS::get_singleton()->print("\n\nTest 27: begins_with\n");
-	test_27_data tc[] = {
-		{ "res://foobar", "res://", true },
-		{ "res", "res://", false },
-		{ "abc", "abc", true }
-	};
-	size_t count = sizeof(tc) / sizeof(tc[0]);
-	bool state = true;
-	for (size_t i = 0; state && i < count; ++i) {
-		String s = tc[i].data;
-		state = s.begins_with(tc[i].begin) == tc[i].expected;
-		if (state) {
-			String sb = tc[i].begin;
-			state = s.begins_with(sb) == tc[i].expected;
-		}
-		if (!state) {
-			OS::get_singleton()->print("\n\t Failure on:\n\t\tstring: %s\n\t\tbegin: %s\n\t\texpected: %s\n", tc[i].data, tc[i].begin, tc[i].expected ? "true" : "false");
-			break;
-		}
-	};
-	return state;
-};
-
-bool test_28() {
-	OS::get_singleton()->print("\n\nTest 28: sprintf\n");
-
-	bool success, state = true;
-	char output_format[] = "\tTest:\t%ls => %ls (%s)\n";
-	String format, output;
-	Array args;
-	bool error;
-
-	// %%
-	format = "fish %% frog";
-	args.clear();
-	output = format.sprintf(args, &error);
-	success = (output == String("fish % frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	//////// INTS
-
-	// Int
-	format = "fish %d frog";
-	args.clear();
-	args.push_back(5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 5 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Int left padded with zeroes.
-	format = "fish %05d frog";
-	args.clear();
-	args.push_back(5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 00005 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Int left padded with spaces.
-	format = "fish %5d frog";
-	args.clear();
-	args.push_back(5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish     5 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Int right padded with spaces.
-	format = "fish %-5d frog";
-	args.clear();
-	args.push_back(5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 5     frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Int with sign (positive).
-	format = "fish %+d frog";
-	args.clear();
-	args.push_back(5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish +5 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Negative int.
-	format = "fish %d frog";
-	args.clear();
-	args.push_back(-5);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish -5 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Hex (lower)
-	format = "fish %x frog";
-	args.clear();
-	args.push_back(45);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 2d frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Hex (upper)
-	format = "fish %X frog";
-	args.clear();
-	args.push_back(45);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 2D frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Octal
-	format = "fish %o frog";
-	args.clear();
-	args.push_back(99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 143 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	////// REALS
-
-	// Real
-	format = "fish %f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 99.990000 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real left-padded
-	format = "fish %11f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish   99.990000 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real right-padded
-	format = "fish %-11f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 99.990000   frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real given int.
-	format = "fish %f frog";
-	args.clear();
-	args.push_back(99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 99.000000 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real with sign (positive).
-	format = "fish %+f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish +99.990000 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real with 1 decimals.
-	format = "fish %.1f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 100.0 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real with 12 decimals.
-	format = "fish %.12f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 99.990000000000 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Real with no decimals.
-	format = "fish %.f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish 100 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	/////// Strings.
-
-	// String
-	format = "fish %s frog";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == String("fish cheese frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// String left-padded
-	format = "fish %10s frog";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == String("fish     cheese frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// String right-padded
-	format = "fish %-10s frog";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == String("fish cheese     frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	///// Characters
-
-	// Character as string.
-	format = "fish %c frog";
-	args.clear();
-	args.push_back("A");
-	output = format.sprintf(args, &error);
-	success = (output == String("fish A frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Character as int.
-	format = "fish %c frog";
-	args.clear();
-	args.push_back(65);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish A frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	///// Dynamic width
-
-	// String dynamic width
-	format = "fish %*s frog";
-	args.clear();
-	args.push_back(10);
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == String("fish     cheese frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Int dynamic width
-	format = "fish %*d frog";
-	args.clear();
-	args.push_back(10);
-	args.push_back(99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish         99 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Float dynamic width
-	format = "fish %*.*f frog";
-	args.clear();
-	args.push_back(10);
-	args.push_back(3);
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == String("fish     99.990 frog") && !error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	///// Errors
-
-	// More formats than arguments.
-	format = "fish %s %s frog";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == "not enough arguments for format string" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// More arguments than formats.
-	format = "fish %s frog";
-	args.clear();
-	args.push_back("hello");
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == "not all arguments converted during string formatting" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Incomplete format.
-	format = "fish %10";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == "incomplete format" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Bad character in format string
-	format = "fish %&f frog";
-	args.clear();
-	args.push_back("cheese");
-	output = format.sprintf(args, &error);
-	success = (output == "unsupported format character" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Too many decimals.
-	format = "fish %2.2.2f frog";
-	args.clear();
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == "too many decimal points in format" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// * not a number
-	format = "fish %*f frog";
-	args.clear();
-	args.push_back("cheese");
-	args.push_back(99.99);
-	output = format.sprintf(args, &error);
-	success = (output == "* wants number" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Character too long.
-	format = "fish %c frog";
-	args.clear();
-	args.push_back("sc");
-	output = format.sprintf(args, &error);
-	success = (output == "%c requires number or single-character string" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	// Character bad type.
-	format = "fish %c frog";
-	args.clear();
-	args.push_back(Array());
-	output = format.sprintf(args, &error);
-	success = (output == "%c requires number or single-character string" && error);
-	OS::get_singleton()->print(output_format, format.c_str(), output.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	return state;
-}
-
-bool test_29() {
-	bool state = true;
-
-	IP_Address ip0("2001:0db8:85a3:0000:0000:8a2e:0370:7334");
-	OS::get_singleton()->print("ip0 is %ls\n", String(ip0).c_str());
-
-	IP_Address ip(0x0123, 0x4567, 0x89ab, 0xcdef, true);
-	OS::get_singleton()->print("ip6 is %ls\n", String(ip).c_str());
-
-	IP_Address ip2("fe80::52e5:49ff:fe93:1baf");
-	OS::get_singleton()->print("ip6 is %ls\n", String(ip2).c_str());
-
-	IP_Address ip3("::ffff:192.168.0.1");
-	OS::get_singleton()->print("ip6 is %ls\n", String(ip3).c_str());
-
-	String ip4 = "192.168.0.1";
-	bool success = ip4.is_valid_ip_address();
-	OS::get_singleton()->print("Is valid ipv4: %ls, %s\n", ip4.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	ip4 = "192.368.0.1";
-	success = (!ip4.is_valid_ip_address());
-	OS::get_singleton()->print("Is invalid ipv4: %ls, %s\n", ip4.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	String ip6 = "2001:0db8:85a3:0000:0000:8a2e:0370:7334";
-	success = ip6.is_valid_ip_address();
-	OS::get_singleton()->print("Is valid ipv6: %ls, %s\n", ip6.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	ip6 = "2001:0db8:85j3:0000:0000:8a2e:0370:7334";
-	success = (!ip6.is_valid_ip_address());
-	OS::get_singleton()->print("Is invalid ipv6: %ls, %s\n", ip6.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	ip6 = "2001:0db8:85f345:0000:0000:8a2e:0370:7334";
-	success = (!ip6.is_valid_ip_address());
-	OS::get_singleton()->print("Is invalid ipv6: %ls, %s\n", ip6.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	ip6 = "2001:0db8::0:8a2e:370:7334";
-	success = (ip6.is_valid_ip_address());
-	OS::get_singleton()->print("Is valid ipv6: %ls, %s\n", ip6.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	ip6 = "::ffff:192.168.0.1";
-	success = (ip6.is_valid_ip_address());
-	OS::get_singleton()->print("Is valid ipv6: %ls, %s\n", ip6.c_str(), success ? "OK" : "FAIL");
-	state = state && success;
-
-	return state;
-};
-
-bool test_30() {
-	bool state = true;
-	bool success = true;
-	String input = "bytes2var";
-	String output = "Bytes 2 Var";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "linear2db";
-	output = "Linear 2 Db";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "vector3";
-	output = "Vector 3";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "sha256";
-	output = "Sha 256";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "2db";
-	output = "2 Db";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "PascalCase";
-	output = "Pascal Case";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "PascalPascalCase";
-	output = "Pascal Pascal Case";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "snake_case";
-	output = "Snake Case";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "snake_snake_case";
-	output = "Snake Snake Case";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "sha256sum";
-	output = "Sha 256 Sum";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "cat2dog";
-	output = "Cat 2 Dog";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "function(name)";
-	output = "Function(name)";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls (existing incorrect behavior): %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "snake_case_function(snake_case_arg)";
-	output = "Snake Case Function(snake Case Arg)";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls (existing incorrect behavior): %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	input = "snake_case_function( snake_case_arg )";
-	output = "Snake Case Function( Snake Case Arg )";
-	success = (input.capitalize() == output);
-	state = state && success;
-	OS::get_singleton()->print("Capitalize %ls: %ls, %s\n", input.c_str(), output.c_str(), success ? "OK" : "FAIL");
-
-	return state;
-}
-
-bool test_31() {
-	bool state = true;
-	bool success;
-
-	String a = "";
-	success = a[0] == 0;
-	OS::get_singleton()->print("Is 0 String[0]:, %s\n", success ? "OK" : "FAIL");
-	if (!success) {
-		state = false;
-	}
-
-	String b = "Godot";
-	success = b[b.size()] == 0;
-	OS::get_singleton()->print("Is 0 String[size()]:, %s\n", success ? "OK" : "FAIL");
-	if (!success) {
-		state = false;
-	}
-
-	const String c = "";
-	success = c[0] == 0;
-	OS::get_singleton()->print("Is 0 const String[0]:, %s\n", success ? "OK" : "FAIL");
-	if (!success) {
-		state = false;
-	}
-
-	const String d = "Godot";
-	success = d[d.size()] == 0;
-	OS::get_singleton()->print("Is 0 const String[size()]:, %s\n", success ? "OK" : "FAIL");
-	if (!success) {
-		state = false;
-	}
-
-	return state;
-};
-
-bool test_32() {
-#define STRIP_TEST(x)                                            \
-	{                                                            \
-		bool success = x;                                        \
-		state = state && success;                                \
-		if (!success) {                                          \
-			OS::get_singleton()->print("\tfailed at: %s\n", #x); \
-		}                                                        \
-	}
-
-	OS::get_singleton()->print("\n\nTest 32: lstrip and rstrip\n");
-	bool state = true;
-
-	// strip none
-	STRIP_TEST(String("abc").lstrip("") == "abc");
-	STRIP_TEST(String("abc").rstrip("") == "abc");
-	// strip one
-	STRIP_TEST(String("abc").lstrip("a") == "bc");
-	STRIP_TEST(String("abc").rstrip("c") == "ab");
-	// strip lots
-	STRIP_TEST(String("bababbababccc").lstrip("ab") == "ccc");
-	STRIP_TEST(String("aaabcbcbcbbcbbc").rstrip("cb") == "aaa");
-	// strip empty string
-	STRIP_TEST(String("").lstrip("") == "");
-	STRIP_TEST(String("").rstrip("") == "");
-	// strip to empty string
-	STRIP_TEST(String("abcabcabc").lstrip("bca") == "");
-	STRIP_TEST(String("abcabcabc").rstrip("bca") == "");
-	// don't strip wrong end
-	STRIP_TEST(String("abc").lstrip("c") == "abc");
-	STRIP_TEST(String("abca").lstrip("a") == "bca");
-	STRIP_TEST(String("abc").rstrip("a") == "abc");
-	STRIP_TEST(String("abca").rstrip("a") == "abc");
-	// in utf-8 "¿" (\u00bf) has the same first byte as "µ" (\u00b5)
-	// and the same second as "ÿ" (\u00ff)
-	STRIP_TEST(String::utf8("¿").lstrip(String::utf8("µÿ")) == String::utf8("¿"));
-	STRIP_TEST(String::utf8("¿").rstrip(String::utf8("µÿ")) == String::utf8("¿"));
-	STRIP_TEST(String::utf8("µ¿ÿ").lstrip(String::utf8("µÿ")) == String::utf8("¿ÿ"));
-	STRIP_TEST(String::utf8("µ¿ÿ").rstrip(String::utf8("µÿ")) == String::utf8("µ¿"));
-
-	// the above tests repeated with additional superfluous strip chars
-
-	// strip none
-	STRIP_TEST(String("abc").lstrip("qwjkl") == "abc");
-	STRIP_TEST(String("abc").rstrip("qwjkl") == "abc");
-	// strip one
-	STRIP_TEST(String("abc").lstrip("qwajkl") == "bc");
-	STRIP_TEST(String("abc").rstrip("qwcjkl") == "ab");
-	// strip lots
-	STRIP_TEST(String("bababbababccc").lstrip("qwabjkl") == "ccc");
-	STRIP_TEST(String("aaabcbcbcbbcbbc").rstrip("qwcbjkl") == "aaa");
-	// strip empty string
-	STRIP_TEST(String("").lstrip("qwjkl") == "");
-	STRIP_TEST(String("").rstrip("qwjkl") == "");
-	// strip to empty string
-	STRIP_TEST(String("abcabcabc").lstrip("qwbcajkl") == "");
-	STRIP_TEST(String("abcabcabc").rstrip("qwbcajkl") == "");
-	// don't strip wrong end
-	STRIP_TEST(String("abc").lstrip("qwcjkl") == "abc");
-	STRIP_TEST(String("abca").lstrip("qwajkl") == "bca");
-	STRIP_TEST(String("abc").rstrip("qwajkl") == "abc");
-	STRIP_TEST(String("abca").rstrip("qwajkl") == "abc");
-	// in utf-8 "¿" (\u00bf) has the same first byte as "µ" (\u00b5)
-	// and the same second as "ÿ" (\u00ff)
-	STRIP_TEST(String::utf8("¿").lstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿"));
-	STRIP_TEST(String::utf8("¿").rstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿"));
-	STRIP_TEST(String::utf8("µ¿ÿ").lstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿ÿ"));
-	STRIP_TEST(String::utf8("µ¿ÿ").rstrip(String::utf8("qwaµÿjkl")) == String::utf8("µ¿"));
-
-	return state;
-
-#undef STRIP_TEST
-}
-
-bool test_33() {
-	OS::get_singleton()->print("\n\nTest 33: parse_utf8(null, -1)\n");
-
-	String empty;
-	return empty.parse_utf8(nullptr, -1);
-}
-
-bool test_34() {
-	OS::get_singleton()->print("\n\nTest 34: Cyrillic to_lower()\n");
-
-	String upper = String::utf8("АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ");
-	String lower = String::utf8("абвгдеёжзийклмнопрстуфхцчшщъыьэюя");
-
-	String test = upper.to_lower();
-
-	bool state = test == lower;
-
-	return state;
-}
-
-bool test_35() {
-#define COUNT_TEST(x)                                            \
-	{                                                            \
-		bool success = x;                                        \
-		state = state && success;                                \
-		if (!success) {                                          \
-			OS::get_singleton()->print("\tfailed at: %s\n", #x); \
-		}                                                        \
-	}
-
-	OS::get_singleton()->print("\n\nTest 35: count and countn function\n");
-	bool state = true;
-
-	COUNT_TEST(String("").count("Test") == 0);
-	COUNT_TEST(String("Test").count("") == 0);
-	COUNT_TEST(String("Test").count("test") == 0);
-	COUNT_TEST(String("Test").count("TEST") == 0);
-	COUNT_TEST(String("TEST").count("TEST") == 1);
-	COUNT_TEST(String("Test").count("Test") == 1);
-	COUNT_TEST(String("aTest").count("Test") == 1);
-	COUNT_TEST(String("Testa").count("Test") == 1);
-	COUNT_TEST(String("TestTestTest").count("Test") == 3);
-	COUNT_TEST(String("TestTestTest").count("TestTest") == 1);
-	COUNT_TEST(String("TestGodotTestGodotTestGodot").count("Test") == 3);
-
-	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 8) == 1);
-	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 12) == 2);
-	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 16) == 3);
-	COUNT_TEST(String("TestTestTestTest").count("Test", 4) == 3);
-
-	COUNT_TEST(String("Test").countn("test") == 1);
-	COUNT_TEST(String("Test").countn("TEST") == 1);
-	COUNT_TEST(String("testTest-Testatest").countn("tEst") == 4);
-	COUNT_TEST(String("testTest-TeStatest").countn("tEsT", 4, 16) == 2);
-
-	return state;
-}
-
-typedef bool (*TestFunc)();
-
-TestFunc test_funcs[] = {
-
-	test_1,
-	test_2,
-	test_3,
-	test_4,
-	test_5,
-	test_6,
-	test_7,
-	test_8,
-	test_9,
-	test_10,
-	test_11,
-	test_12,
-	test_13,
-	test_14,
-	test_15,
-	test_16,
-	test_17,
-	test_18,
-	test_19,
-	test_20,
-	test_21,
-	test_22,
-	test_23,
-	test_24,
-	test_25,
-	test_26,
-	test_27,
-	test_28,
-	test_29,
-	test_30,
-	test_31,
-	test_32,
-	test_33,
-	test_34,
-	test_35,
-	nullptr
-
-};
-
-MainLoop *test() {
-	/** A character length != wchar_t may be forced, so the tests won't work */
-
-	static_assert(sizeof(CharType) == sizeof(wchar_t));
-
-	int count = 0;
-	int passed = 0;
-
-	while (true) {
-		if (!test_funcs[count]) {
-			break;
-		}
-		bool pass = test_funcs[count]();
-		if (pass) {
-			passed++;
-		}
-		OS::get_singleton()->print("\t%s\n", pass ? "PASS" : "FAILED");
-
-		count++;
-	}
-
-	OS::get_singleton()->print("\n\n\n");
-	OS::get_singleton()->print("*************\n");
-	OS::get_singleton()->print("***TOTALS!***\n");
-	OS::get_singleton()->print("*************\n");
-
-	OS::get_singleton()->print("Passed %i of %i tests\n", passed, count);
-
-	return nullptr;
-}
-
-} // namespace TestString
diff --git a/main/tests/test_string.h b/main/tests/test_string.h
index 96fa811126..25fd513a1a 100644
--- a/main/tests/test_string.h
+++ b/main/tests/test_string.h
@@ -31,12 +31,768 @@
 #ifndef TEST_STRING_H
 #define TEST_STRING_H
 
+#include <inttypes.h>
+#include <stdio.h>
+#include <wchar.h>
+
+#include "core/io/ip_address.h"
 #include "core/os/main_loop.h"
+#include "core/os/os.h"
 #include "core/ustring.h"
 
+#ifdef MODULE_REGEX_ENABLED
+#include "modules/regex/regex.h"
+#endif
+
+#include "thirdparty/doctest/doctest.h"
+
 namespace TestString {
 
-MainLoop *test();
+TEST_CASE("[String] Assign from cstr") {
+	String s = "Hello";
+	CHECK(wcscmp(s.c_str(), L"Hello") == 0);
+}
+
+TEST_CASE("[String] Assign from string (operator=)") {
+	String s = "Dolly";
+	const String &t = s;
+	CHECK(wcscmp(t.c_str(), L"Dolly") == 0);
+}
+
+TEST_CASE("[String] Assign from c-string (copycon)") {
+	String s("Sheep");
+	const String &t(s);
+	CHECK(wcscmp(t.c_str(), L"Sheep") == 0);
+}
+
+TEST_CASE("[String] Assign from c-widechar (operator=)") {
+	String s(L"Give me");
+	CHECK(wcscmp(s.c_str(), L"Give me") == 0);
+}
+
+TEST_CASE("[String] Assign from c-widechar (copycon)") {
+	String s(L"Wool");
+	CHECK(wcscmp(s.c_str(), L"Wool") == 0);
+}
+
+TEST_CASE("[String] Comparisons (equal)") {
+	String s = "Test Compare";
+	CHECK(s == "Test Compare");
+	CHECK(s == L"Test Compare");
+	CHECK(s == String("Test Compare"));
+}
+
+TEST_CASE("[String] Comparisons (not equal)") {
+	String s = "Test Compare";
+	CHECK(s != "Peanut");
+	CHECK(s != L"Coconut");
+	CHECK(s != String("Butter"));
+}
+
+TEST_CASE("[String] Comparisons (operator <)") {
+	String s = "Bees";
+	CHECK(s < "Elephant");
+	CHECK(!(s < L"Amber"));
+	CHECK(!(s < String("Beatrix")));
+}
+
+TEST_CASE("[String] Concatenation") {
+	String s;
+
+	s += "Have";
+	s += ' ';
+	s += 'a';
+	s += String(" ");
+	s = s + L"Nice";
+	s = s + " ";
+	s = s + String("Day");
+
+	CHECK(s == "Have a Nice Day");
+}
+
+TEST_CASE("[String] Testing size and length of string") {
+	// todo: expand this test to do more tests on size() as it is complicated under the hood.
+	CHECK(String("Mellon").size() == 7);
+	CHECK(String("Mellon1").size() == 8);
+
+	// length works fine and is easier to test
+	CHECK(String("Mellon").length() == 6);
+	CHECK(String("Mellon1").length() == 7);
+	CHECK(String("Mellon2").length() == 7);
+	CHECK(String("Mellon3").length() == 7);
+}
+
+TEST_CASE("[String] Testing for empty string") {
+	CHECK(!String("Mellon").empty());
+	// do this more than once, to check for string corruption
+	CHECK(String("").empty());
+	CHECK(String("").empty());
+	CHECK(String("").empty());
+}
+
+TEST_CASE("[String] Operator []") {
+	String a = "Kugar Sane";
+	a[0] = 'S';
+	a[6] = 'C';
+	CHECK(a == "Sugar Cane");
+	CHECK(a[1] == 'u');
+}
+
+TEST_CASE("[String] Case function test") {
+	String a = "MoMoNgA";
+
+	CHECK(a.to_upper() == "MOMONGA");
+	CHECK(a.nocasecmp_to("momonga") == 0);
+}
+
+TEST_CASE("[String] UTF8") {
+	/* how can i embed UTF in here? */
+	static const CharType ustr[] = { 0x304A, 0x360F, 0x3088, 0x3046, 0 };
+	//static const wchar_t ustr[] = { 'P', 0xCE, 'p',0xD3, 0 };
+	String s = ustr;
+	s.parse_utf8(s.utf8().get_data());
+	CHECK(s == ustr);
+}
+
+TEST_CASE("[String] ASCII") {
+	String s = L"Primero Leche";
+	String t = s.ascii().get_data();
+	CHECK(s == t);
+}
+
+TEST_CASE("[String] Substr") {
+	String s = "Killer Baby";
+	CHECK(s.substr(3, 4) == "ler ");
+}
+
+TEST_CASE("[string] Find") {
+	String s = "Pretty Woman";
+	s.find("Revenge of the Monster Truck");
+
+	CHECK(s.find("tty") == 3);
+	CHECK(s.find("Revenge of the Monster Truck") == -1);
+}
+
+TEST_CASE("[String] find no case") {
+	String s = "Pretty Whale";
+	CHECK(s.findn("WHA") == 7);
+	CHECK(s.findn("Revenge of the Monster SawFish") == -1);
+}
+
+TEST_CASE("[String] Find and replace") {
+	String s = "Happy Birthday, Anna!";
+	s = s.replace("Birthday", "Halloween");
+	CHECK(s == "Happy Halloween, Anna!");
+}
+
+TEST_CASE("[String] Insertion") {
+	String s = "Who is Frederic?";
+	s = s.insert(s.find("?"), " Chopin");
+	CHECK(s == "Who is Frederic Chopin?");
+}
+
+TEST_CASE("[String] Number to string") {
+	CHECK(String::num(3.141593) == "3.141593");
 }
 
+TEST_CASE("[String] String to integer") {
+	static const char *nums[4] = { "1237461283", "- 22", "0", " - 1123412" };
+	static const int num[4] = { 1237461283, -22, 0, -1123412 };
+
+	for (int i = 0; i < 4; i++) {
+		CHECK(String(nums[i]).to_int() == num[i]);
+	}
+}
+
+TEST_CASE("[String] String to float") {
+	static const char *nums[4] = { "-12348298412.2", "0.05", "2.0002", " -0.0001" };
+	static const double num[4] = { -12348298412.2, 0.05, 2.0002, -0.0001 };
+
+	for (int i = 0; i < 4; i++) {
+		CHECK(!(ABS(String(nums[i]).to_double() - num[i]) > 0.00001));
+	}
+}
+
+TEST_CASE("[String] Slicing") {
+	String s = "Mars,Jupiter,Saturn,Uranus";
+
+	const char *slices[4] = { "Mars", "Jupiter", "Saturn", "Uranus" };
+	for (int i = 0; i < s.get_slice_count(","); i++) {
+		CHECK(s.get_slice(",", i) == slices[i]);
+	}
+}
+
+TEST_CASE("[String] Erasing") {
+	String s = "Josephine is such a cute girl!";
+	s.erase(s.find("cute "), String("cute ").length());
+	CHECK(s == "Josephine is such a girl!");
+}
+
+#ifdef MODULE_REGEX_ENABLED
+TEST_CASE("[String] Regex substitution") {
+	String s = "Double all the vowels.";
+	RegEx re("(?<vowel>[aeiou])");
+	s = re.sub(s, "$0$vowel", true);
+	CHECK(s == "Doouublee aall thee vooweels.");
+}
 #endif
+
+struct test_27_data {
+	char const *data;
+	char const *begin;
+	bool expected;
+};
+
+TEST_CASE("[String] Begins with") {
+	test_27_data tc[] = {
+		{ "res://foobar", "res://", true },
+		{ "res", "res://", false },
+		{ "abc", "abc", true }
+	};
+	size_t count = sizeof(tc) / sizeof(tc[0]);
+	bool state = true;
+	for (size_t i = 0; state && i < count; ++i) {
+		String s = tc[i].data;
+		state = s.begins_with(tc[i].begin) == tc[i].expected;
+		if (state) {
+			String sb = tc[i].begin;
+			state = s.begins_with(sb) == tc[i].expected;
+		}
+		CHECK(state);
+		if (!state) {
+			break;
+		}
+	};
+	CHECK(state);
+}
+
+TEST_CASE("[String] sprintf") {
+	String format, output;
+	Array args;
+	bool error;
+
+	// %%
+	format = "fish %% frog";
+	args.clear();
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish % frog"));
+	//////// INTS
+
+	// Int
+	format = "fish %d frog";
+	args.clear();
+	args.push_back(5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 5 frog"));
+
+	// Int left padded with zeroes.
+	format = "fish %05d frog";
+	args.clear();
+	args.push_back(5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 00005 frog"));
+
+	// Int left padded with spaces.
+	format = "fish %5d frog";
+	args.clear();
+	args.push_back(5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish     5 frog"));
+
+	// Int right padded with spaces.
+	format = "fish %-5d frog";
+	args.clear();
+	args.push_back(5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 5     frog"));
+
+	// Int with sign (positive).
+	format = "fish %+d frog";
+	args.clear();
+	args.push_back(5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish +5 frog"));
+
+	// Negative int.
+	format = "fish %d frog";
+	args.clear();
+	args.push_back(-5);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish -5 frog"));
+
+	// Hex (lower)
+	format = "fish %x frog";
+	args.clear();
+	args.push_back(45);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 2d frog"));
+
+	// Hex (upper)
+	format = "fish %X frog";
+	args.clear();
+	args.push_back(45);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 2D frog"));
+
+	// Octal
+	format = "fish %o frog";
+	args.clear();
+	args.push_back(99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 143 frog"));
+
+	////// REALS
+
+	// Real
+	format = "fish %f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 99.990000 frog"));
+
+	// Real left-padded
+	format = "fish %11f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish   99.990000 frog"));
+
+	// Real right-padded
+	format = "fish %-11f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 99.990000   frog"));
+
+	// Real given int.
+	format = "fish %f frog";
+	args.clear();
+	args.push_back(99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 99.000000 frog"));
+
+	// Real with sign (positive).
+	format = "fish %+f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish +99.990000 frog"));
+
+	// Real with 1 decimals.
+	format = "fish %.1f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 100.0 frog"));
+
+	// Real with 12 decimals.
+	format = "fish %.12f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 99.990000000000 frog"));
+
+	// Real with no decimals.
+	format = "fish %.f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish 100 frog"));
+
+	/////// Strings.
+
+	// String
+	format = "fish %s frog";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish cheese frog"));
+
+	// String left-padded
+	format = "fish %10s frog";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish     cheese frog"));
+
+	// String right-padded
+	format = "fish %-10s frog";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish cheese     frog"));
+
+	///// Characters
+
+	// Character as string.
+	format = "fish %c frog";
+	args.clear();
+	args.push_back("A");
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish A frog"));
+
+	// Character as int.
+	format = "fish %c frog";
+	args.clear();
+	args.push_back(65);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish A frog"));
+
+	///// Dynamic width
+
+	// String dynamic width
+	format = "fish %*s frog";
+	args.clear();
+	args.push_back(10);
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	REQUIRE(output == String("fish     cheese frog"));
+
+	// Int dynamic width
+	format = "fish %*d frog";
+	args.clear();
+	args.push_back(10);
+	args.push_back(99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	REQUIRE(output == String("fish         99 frog"));
+
+	// Float dynamic width
+	format = "fish %*.*f frog";
+	args.clear();
+	args.push_back(10);
+	args.push_back(3);
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish     99.990 frog"));
+
+	///// Errors
+
+	// More formats than arguments.
+	format = "fish %s %s frog";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "not enough arguments for format string");
+
+	// More arguments than formats.
+	format = "fish %s frog";
+	args.clear();
+	args.push_back("hello");
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "not all arguments converted during string formatting");
+
+	// Incomplete format.
+	format = "fish %10";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "incomplete format");
+
+	// Bad character in format string
+	format = "fish %&f frog";
+	args.clear();
+	args.push_back("cheese");
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "unsupported format character");
+
+	// Too many decimals.
+	format = "fish %2.2.2f frog";
+	args.clear();
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "too many decimal points in format");
+
+	// * not a number
+	format = "fish %*f frog";
+	args.clear();
+	args.push_back("cheese");
+	args.push_back(99.99);
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "* wants number");
+
+	// Character too long.
+	format = "fish %c frog";
+	args.clear();
+	args.push_back("sc");
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "%c requires number or single-character string");
+
+	// Character bad type.
+	format = "fish %c frog";
+	args.clear();
+	args.push_back(Array());
+	output = format.sprintf(args, &error);
+	REQUIRE(error);
+	CHECK(output == "%c requires number or single-character string");
+}
+
+TEST_CASE("[String] IPVX address to string") {
+	IP_Address ip0("2001:0db8:85a3:0000:0000:8a2e:0370:7334");
+	IP_Address ip(0x0123, 0x4567, 0x89ab, 0xcdef, true);
+	IP_Address ip2("fe80::52e5:49ff:fe93:1baf");
+	IP_Address ip3("::ffff:192.168.0.1");
+	String ip4 = "192.168.0.1";
+	CHECK(ip4.is_valid_ip_address());
+
+	ip4 = "192.368.0.1";
+	CHECK(!ip4.is_valid_ip_address());
+
+	String ip6 = "2001:0db8:85a3:0000:0000:8a2e:0370:7334";
+	CHECK(ip6.is_valid_ip_address());
+
+	ip6 = "2001:0db8:85j3:0000:0000:8a2e:0370:7334";
+	CHECK(!ip6.is_valid_ip_address());
+
+	ip6 = "2001:0db8:85f345:0000:0000:8a2e:0370:7334";
+	CHECK(!ip6.is_valid_ip_address());
+
+	ip6 = "2001:0db8::0:8a2e:370:7334";
+	CHECK(ip6.is_valid_ip_address());
+
+	ip6 = "::ffff:192.168.0.1";
+	CHECK(ip6.is_valid_ip_address());
+}
+
+TEST_CASE("[String] Capitalize against many strings") {
+	String input = "bytes2var";
+	String output = "Bytes 2 Var";
+	CHECK(input.capitalize() == output);
+
+	input = "linear2db";
+	output = "Linear 2 Db";
+	CHECK(input.capitalize() == output);
+
+	input = "vector3";
+	output = "Vector 3";
+	CHECK(input.capitalize() == output);
+
+	input = "sha256";
+	output = "Sha 256";
+	CHECK(input.capitalize() == output);
+
+	input = "2db";
+	output = "2 Db";
+	CHECK(input.capitalize() == output);
+
+	input = "PascalCase";
+	output = "Pascal Case";
+	CHECK(input.capitalize() == output);
+
+	input = "PascalPascalCase";
+	output = "Pascal Pascal Case";
+	CHECK(input.capitalize() == output);
+
+	input = "snake_case";
+	output = "Snake Case";
+	CHECK(input.capitalize() == output);
+
+	input = "snake_snake_case";
+	output = "Snake Snake Case";
+	CHECK(input.capitalize() == output);
+
+	input = "sha256sum";
+	output = "Sha 256 Sum";
+	CHECK(input.capitalize() == output);
+
+	input = "cat2dog";
+	output = "Cat 2 Dog";
+	CHECK(input.capitalize() == output);
+
+	input = "function(name)";
+	output = "Function(name)";
+	CHECK(input.capitalize() == output);
+
+	input = "snake_case_function(snake_case_arg)";
+	output = "Snake Case Function(snake Case Arg)";
+	CHECK(input.capitalize() == output);
+
+	input = "snake_case_function( snake_case_arg )";
+	output = "Snake Case Function( Snake Case Arg )";
+	CHECK(input.capitalize() == output);
+}
+
+TEST_CASE("[String] Checking string is empty when it should be") {
+	bool state = true;
+	bool success;
+
+	String a = "";
+	success = a[0] == 0;
+	if (!success) {
+		state = false;
+	}
+	String b = "Godot";
+	success = b[b.size()] == 0;
+	if (!success) {
+		state = false;
+	}
+	const String c = "";
+	success = c[0] == 0;
+	if (!success) {
+		state = false;
+	}
+
+	const String d = "Godot";
+	success = d[d.size()] == 0;
+	if (!success) {
+		state = false;
+	}
+
+	CHECK(state);
+}
+
+TEST_CASE("[String] lstrip and rstrip") {
+#define STRIP_TEST(x)             \
+	{                             \
+		bool success = x;         \
+		state = state && success; \
+	}
+
+	bool state = true;
+
+	// strip none
+	STRIP_TEST(String("abc").lstrip("") == "abc");
+	STRIP_TEST(String("abc").rstrip("") == "abc");
+	// strip one
+	STRIP_TEST(String("abc").lstrip("a") == "bc");
+	STRIP_TEST(String("abc").rstrip("c") == "ab");
+	// strip lots
+	STRIP_TEST(String("bababbababccc").lstrip("ab") == "ccc");
+	STRIP_TEST(String("aaabcbcbcbbcbbc").rstrip("cb") == "aaa");
+	// strip empty string
+	STRIP_TEST(String("").lstrip("") == "");
+	STRIP_TEST(String("").rstrip("") == "");
+	// strip to empty string
+	STRIP_TEST(String("abcabcabc").lstrip("bca") == "");
+	STRIP_TEST(String("abcabcabc").rstrip("bca") == "");
+	// don't strip wrong end
+	STRIP_TEST(String("abc").lstrip("c") == "abc");
+	STRIP_TEST(String("abca").lstrip("a") == "bca");
+	STRIP_TEST(String("abc").rstrip("a") == "abc");
+	STRIP_TEST(String("abca").rstrip("a") == "abc");
+	// in utf-8 "¿" (\u00bf) has the same first byte as "µ" (\u00b5)
+	// and the same second as "ÿ" (\u00ff)
+	STRIP_TEST(String::utf8("¿").lstrip(String::utf8("µÿ")) == String::utf8("¿"));
+	STRIP_TEST(String::utf8("¿").rstrip(String::utf8("µÿ")) == String::utf8("¿"));
+	STRIP_TEST(String::utf8("µ¿ÿ").lstrip(String::utf8("µÿ")) == String::utf8("¿ÿ"));
+	STRIP_TEST(String::utf8("µ¿ÿ").rstrip(String::utf8("µÿ")) == String::utf8("µ¿"));
+
+	// the above tests repeated with additional superfluous strip chars
+
+	// strip none
+	STRIP_TEST(String("abc").lstrip("qwjkl") == "abc");
+	STRIP_TEST(String("abc").rstrip("qwjkl") == "abc");
+	// strip one
+	STRIP_TEST(String("abc").lstrip("qwajkl") == "bc");
+	STRIP_TEST(String("abc").rstrip("qwcjkl") == "ab");
+	// strip lots
+	STRIP_TEST(String("bababbababccc").lstrip("qwabjkl") == "ccc");
+	STRIP_TEST(String("aaabcbcbcbbcbbc").rstrip("qwcbjkl") == "aaa");
+	// strip empty string
+	STRIP_TEST(String("").lstrip("qwjkl") == "");
+	STRIP_TEST(String("").rstrip("qwjkl") == "");
+	// strip to empty string
+	STRIP_TEST(String("abcabcabc").lstrip("qwbcajkl") == "");
+	STRIP_TEST(String("abcabcabc").rstrip("qwbcajkl") == "");
+	// don't strip wrong end
+	STRIP_TEST(String("abc").lstrip("qwcjkl") == "abc");
+	STRIP_TEST(String("abca").lstrip("qwajkl") == "bca");
+	STRIP_TEST(String("abc").rstrip("qwajkl") == "abc");
+	STRIP_TEST(String("abca").rstrip("qwajkl") == "abc");
+	// in utf-8 "¿" (\u00bf) has the same first byte as "µ" (\u00b5)
+	// and the same second as "ÿ" (\u00ff)
+	STRIP_TEST(String::utf8("¿").lstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿"));
+	STRIP_TEST(String::utf8("¿").rstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿"));
+	STRIP_TEST(String::utf8("µ¿ÿ").lstrip(String::utf8("qwaµÿjkl")) == String::utf8("¿ÿ"));
+	STRIP_TEST(String::utf8("µ¿ÿ").rstrip(String::utf8("qwaµÿjkl")) == String::utf8("µ¿"));
+
+	CHECK(state);
+
+#undef STRIP_TEST
+}
+
+TEST_CASE("[String] ensuring empty string into parse_utf8 passes empty string") {
+	String empty;
+	CHECK(empty.parse_utf8(NULL, -1));
+}
+
+TEST_CASE("[String] Cyrillic to_lower()") {
+	String upper = String::utf8("АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ");
+	String lower = String::utf8("абвгдеёжзийклмнопрстуфхцчшщъыьэюя");
+
+	String test = upper.to_lower();
+
+	bool state = test == lower;
+
+	CHECK(state);
+}
+
+TEST_CASE("[String] Count and countn functionality") {
+#define COUNT_TEST(x)             \
+	{                             \
+		bool success = x;         \
+		state = state && success; \
+	}
+
+	bool state = true;
+
+	COUNT_TEST(String("").count("Test") == 0);
+	COUNT_TEST(String("Test").count("") == 0);
+	COUNT_TEST(String("Test").count("test") == 0);
+	COUNT_TEST(String("Test").count("TEST") == 0);
+	COUNT_TEST(String("TEST").count("TEST") == 1);
+	COUNT_TEST(String("Test").count("Test") == 1);
+	COUNT_TEST(String("aTest").count("Test") == 1);
+	COUNT_TEST(String("Testa").count("Test") == 1);
+	COUNT_TEST(String("TestTestTest").count("Test") == 3);
+	COUNT_TEST(String("TestTestTest").count("TestTest") == 1);
+	COUNT_TEST(String("TestGodotTestGodotTestGodot").count("Test") == 3);
+
+	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 8) == 1);
+	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 12) == 2);
+	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 16) == 3);
+	COUNT_TEST(String("TestTestTestTest").count("Test", 4) == 3);
+
+	COUNT_TEST(String("Test").countn("test") == 1);
+	COUNT_TEST(String("Test").countn("TEST") == 1);
+	COUNT_TEST(String("testTest-Testatest").countn("tEst") == 4);
+	COUNT_TEST(String("testTest-TeStatest").countn("tEsT", 4, 16) == 2);
+
+	CHECK(state);
+}
+} // namespace TestString
+
+#endif // TEST_STRING_H
diff --git a/main/tests/test_validate_testing.h b/main/tests/test_validate_testing.h
new file mode 100644
index 0000000000..5be7d45185
--- /dev/null
+++ b/main/tests/test_validate_testing.h
@@ -0,0 +1,42 @@
+/*************************************************************************/
+/*  test_validate_testing.h                                              */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef TEST_VALIDATE_TESTING_H
+#define TEST_VALIDATE_TESTING_H
+
+#include "core/os/os.h"
+
+#include "thirdparty/doctest/doctest.h"
+
+TEST_CASE("Validate Test will always pass") {
+	CHECK(true);
+}
+
+#endif // TEST_VALIDATE_TESTING_H
-- 
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