def METHOD_NAME(self) -> None:
    """Test get_package_file_contents with imaginary binary file."""
    with self.swap_to_always_return(pkgutil, 'get_data', 'File data'):
        self.assertEqual(
            constants.get_package_file_contents(
                'assets', 'non_exist.xy', binary_mode=True), 'File data'
        )