chore: add GUT test framework

addons/gut/test/unit/test_shell_out_options_dialog.gd

@@ -0,0 +1,43 @@
+extends GutInternalTester
+
+
+var DialogScene = load("res://addons/gut/gui/ShellOutOptions.tscn")
+
+func test_can_make_one():
+	var inst = DialogScene.instantiate()
+	assert_not_null(inst)
+	inst.free()
+
+var split_param = ParameterFactory.named_parameters(
+	['args', 'result'],
+	[
+		['--a', ['--a']],
+		['   -b     -x    ', ['-b', '-x']],
+		['-r "hello world"', ['-r', '"hello', 'world"']]
+	]
+)
+func test_arg_splitting(p = use_parameters(split_param)):
+	var inst = autofree(DialogScene.instantiate())
+	inst.additional_arguments = p.args
+	var packed_results = PackedStringArray(p.result)
+	assert_eq(inst.get_additional_arguments_array(), packed_results)
+
+
+var invalid_args = ParameterFactory.named_parameters(
+	['args', 'valid_blocking', 'valid_non_blocking'],
+	[
+		['-d', false, false], ['--debug', false , false],
+		['-s', false, false], ['--script', false, false],
+		['-e', false, false], ['--editor', false, false],
+		['--headless', false, true]
+	]
+)
+func test_invalid_arguments(p = use_parameters(invalid_args)):
+	var inst = autofree(DialogScene.instantiate())
+	inst.additional_arguments = p.args
+	inst.run_mode = inst.RUN_MODE_BLOCKING
+	assert_eq(inst.validate_arguments(), p.valid_blocking, str('"',p.args, '" is valid for blocking'))
+	inst.run_mode = inst.RUN_MODE_NON_BLOCKING
+	assert_eq(inst.validate_arguments(), p.valid_non_blocking, str('"', p.args, '" is valid for non-blocking'))
+
+