chore: add GUT test framework

addons/gut/test/unit/test_stubs.gd

@@ -0,0 +1,26 @@
+extends GutInternalTester
+
+var Stubs = GutUtils.Stubs
+var StubParams = GutUtils.StubParams
+
+func test_can_make_one():
+	var s = Stubs.new()
+	assert_not_null(s)
+
+
+"""
+var dbl = doubler.double_singleton(Input).new()
+var method = 'is_action_just_pressed'
+assert_eq(stubber.get_default_value(dbl, method, 0), null)
+assert_eq(stubber.get_default_value(dbl, method, 1), false)
+"""
+
+func test_that_one_thing():
+	var s = Stubs.new()
+	var sp = StubParams.new(Input, GutUtils.find_method_meta(Input.get_method_list(), 'is_action_just_pressed'))
+	s.add_stub(sp)
+	var matches = s.get_all_stubs(Input, 'is_action_just_pressed')
+	assert_eq(matches.size(), 1)
+	if(is_failing()):
+		print(s.to_s())
+