def METHOD_NAME(self):
    """Test installing extension from directory"""
    self.assertModule(
        "g.extension",
        extension="r.plus.example",
        url=os.path.join(self.path, "r.plus.example"),
        prefix=self.install_prefix,
    )
    # TODO: this is wrong for MS Win
    for file in self.files:
        self.assertFileExists(file)