[tests] Add TEST_CONFORM_TODO macro

The TEST_CONFORM_TODO macro is a simple placeholder macro that
adds the test function to the "/todo" namespace and skips the
test.

It can be used for tests that are known to fail because of bugs
that haven't been fixed yet, or because of features not yet
implemented.

tests/conform/test-conform-main.c

@@ -48,6 +48,14 @@ test_conform_skip_test (TestConformSimpleFixture *fixture,
                 test_conform_simple_fixture_teardown);                  \
   } else { TEST_CONFORM_SIMPLE (NAMESPACE, FUNC); }     } G_STMT_END
 
+#define TEST_CONFORM_TODO(NAMESPACE, FUNC)              G_STMT_START {  \
+  g_test_add ("/todo" NAMESPACE "/" #FUNC,                              \
+              TestConformSimpleFixture,                                 \
+              shared_state,                                             \
+              test_conform_simple_fixture_setup,                        \
+              test_conform_skip_test,                                   \
+              test_conform_simple_fixture_teardown);    } G_STMT_END
+
 int
 main (int argc, char **argv)
 {