def test_register_image_importer(is_file): from menpo.image import Image image = Image.init_blank((10, 10)) def foo_importer(filepath, **kwargs): return image is_file.return_value = True with patch.dict(mio.input.extensions.image_types, {}, clear=True): mio.register_image_importer('.foo', foo_importer) new_image = mio.import_image('fake.foo') assert image is new_image