chore: add GUT test framework

addons/gut/scratch/optparse_example.gd

@@ -0,0 +1,53 @@
+extends SceneTree
+
+var OptParse = load('res://addons/gut/cli/optparse.gd')
+
+func _init():
+	var opts = OptParse.new()
+	opts.banner = \
+"""
+This is an example banner so you can see that it is displayed when you specify
+the --hlp option.
+"""
+	opts.add_positional_required("name", "", "Your name")
+	opts.add_positional("fav_letter", "", "Favorite Letter (optional)")
+
+	opts.add("--foo", "bar", "Ubiquitous foobar.")
+	opts.add("--disabled", false, "Disables something.")
+	opts.add("--list", ['a', 'b'], "This is a list of things.")
+	opts.add("--volume", 10, "The volume.  Default is not 11, it is [default]")
+	opts.add_required("--fav_number", 9, "We must know your favorite number.")
+
+	opts.add_heading("The Other Stuff")
+	opts.add("--float_val", 1.5, "This float will be [default] if you do not specify it.")
+	var help_flag = opts.add("--hlp", false, "--help is used by Godot, so we need a different one.")
+
+	# This will parse OS.get_cmdline_args and OS.get_cmdline_user_args.  You
+	# can pass any array into this though and limit which arguments you want
+	# to process.
+	opts.parse()
+	var missing = opts.get_missing_required_options()
+	var unused = opts.unused
+
+	if(help_flag.value):
+		opts.print_help()
+		quit(0)
+	elif(missing.size() > 0):
+		print('Required options missing')
+		for m in missing:
+			print('  ', m.to_s())
+		quit(1)
+	elif(unused.size() > 0):
+		print("Unknown options:  ", unused)
+		quit(1)
+	elif(opts.get_value("--disabled")):
+		print("You have disabled it, so we will do nothing.")
+		print("Even though nothing is still soemthing and this")
+		print("is clearly something...we shall nevertheless")
+		print("consider this nothing")
+		print("Quit this yourself")
+	else:
+		if(opts.get_value("name") == "Me"):
+			print("--- Hello me, it's you! ---")
+		opts.options.print_option_values()
+		quit(0)