GD-497: Execute the test discovery in an additional thread so as not …

…to block the main thread.

# Why
see #497

# What
Moved the time-consuming scanning part into an extra thread to not block the main thread anymore.

addons/gdUnit4/src/core/discovery/GdUnitTestDiscoverer.gd

@@ -7,19 +7,29 @@ static func run() -> void:
 	GdUnitSignals.instance().gdunit_event.emit(GdUnitEventTestDiscoverStart.new())
 	await Engine.get_main_loop().create_timer(.5).timeout
 
-	var test_suite_directories :PackedStringArray = GdUnitCommandHandler.scan_test_directorys("res://" , GdUnitSettings.test_root_folder(), [])
-	var scanner := GdUnitTestSuiteScanner.new()
-	var _test_suites_to_process :Array[Node] = []
-	for test_suite_dir in test_suite_directories:
-		_test_suites_to_process.append_array(scanner.scan(test_suite_dir))
+	# We run the test discovery in an extra thread so that the main thread is not blocked
+	var t:= Thread.new()
+	t.start(func () -> void:
+		var test_suite_directories :PackedStringArray = GdUnitCommandHandler.scan_test_directorys("res://" , GdUnitSettings.test_root_folder(), [])
+		var scanner := GdUnitTestSuiteScanner.new()
+		var _test_suites_to_process :Array[Node] = []
 
-	var test_case_count :int = _test_suites_to_process.reduce(func (accum :int, test_suite :Node) -> int:
-				return accum + test_suite.get_child_count(), 0)
+		for test_suite_dir in test_suite_directories:
+			_test_suites_to_process.append_array(scanner.scan(test_suite_dir))
 
-	for test_suite in _test_suites_to_process:
-		var ts_dto := GdUnitTestSuiteDto.of(test_suite)
-		GdUnitSignals.instance().gdunit_add_test_suite.emit(ts_dto)
+		# Do sync the main thread before emit the discovered test suites to the inspector
+		await Engine.get_main_loop().process_frame
+		for test_suite in _test_suites_to_process:
+			var ts_dto := GdUnitTestSuiteDto.of(test_suite)
+			GdUnitSignals.instance().gdunit_add_test_suite.emit(ts_dto)
 
-	prints("%d test suites discovered." % _test_suites_to_process.size())
-	GdUnitSignals.instance().gdunit_event.emit(GdUnitEventTestDiscoverEnd.new(_test_suites_to_process.size(), test_case_count))
-	await Engine.get_main_loop().process_frame
+		prints("%d test suites discovered." % _test_suites_to_process.size())
+		var test_case_count :int = _test_suites_to_process.reduce(func (accum :int, test_suite :Node) -> int:
+					return accum + test_suite.get_child_count(), 0)
+		GdUnitSignals.instance().gdunit_event.emit(GdUnitEventTestDiscoverEnd.new(_test_suites_to_process.size(), test_case_count))
+	)
+	# wait unblocked to the tread is finished
+	while t.is_alive():
+		await Engine.get_main_loop().process_frame
+	# needs finally to wait for finish
+	await t.wait_to_finish()