chore: add GUT test framework

addons/gut/test/integration/test_gut_and_spy.gd

@@ -0,0 +1,25 @@
+extends GutInternalTester
+
+
+func test_can_get_spy():
+	var g = autofree(new_gut(verbose))
+	assert_ne(g.get_spy(), null)
+
+func test_spy_for_doubler_is_guts_spy():
+	var g = autofree(new_gut(verbose))
+	assert_eq(g.get_doubler().get_spy(), g.get_spy())
+
+
+# ---------------------------------
+# these two tests use the gut instance that is passed to THIS test.  This isn't
+# PURE testing but it appears to cover the bases ok.
+class TestGutClearsSpyBetweenTests:
+	extends 'res://addons/gut/test.gd'
+
+	func test_spy_cleared_between_tests_setup():
+		gut.get_spy().add_call('thing', 'method')
+		assert_true(gut.get_spy().was_called('thing', 'method'))
+
+	func test_spy_cleared_between_tests():
+		assert_false(gut.get_spy().was_called('thing', 'method'))
+# ---------------------------------