How to use the approvaltests.TextDiffReporter.TextDiffReporter function in approvaltests

def instantiate_reporter_for_test():
        reporter = TextDiffReporter()
        reporter.run_command = lambda command_array: None
        return reporter

def setUp(self):
        if os.path.exists(self.tmp_dir):
            shutil.rmtree(self.tmp_dir)
        os.mkdir(self.tmp_dir)
        self.diff_tool = 'echo'
        self.set_environment_variable(
            TextDiffReporter.DIFF_TOOL_ENVIRONMENT_VARIABLE_NAME,
            self.diff_tool
        )

def __init__(self):
        if self.DIFF_TOOL_ENVIRONMENT_VARIABLE_NAME not in os.environ:
            raise ReporterMissingException(self.DIFF_TOOL_ENVIRONMENT_VARIABLE_NAME)
        diff_tool = os.environ[self.DIFF_TOOL_ENVIRONMENT_VARIABLE_NAME]
        super(TextDiffReporter, self).__init__(('Custom', diff_tool))

def test(self):
        reporter = TextDiffReporter()
        approvals.verify("x", reporter)