def METHOD_NAME(self, source_code=None):
    loader = TestingImporter()
    if source_code is not None:
        loader.source_code = source_code
    spec = util.spec_from_loader(TestingImporter.module_name,
                                 util.LazyLoader(loader))
    module = spec.loader.create_module(spec)
    if module is None:
        module = types.ModuleType(TestingImporter.module_name)
    module.__spec__ = spec
    module.__loader__ = spec.loader
    spec.loader.exec_module(module)
    # Module is now lazy.
    self.assertIsNone(loader.loaded)
    return module