def METHOD_NAME(self, recwarn):
    @deprecated_keyword_arg("a", "1.3.0", reason="With some reason message.")
    def simple_addition(a=Deprecated, b=1):
        result = a if a is Deprecated else a + b
        return result
    warn_msg_expected = (
        "Keyword argument 'a' in 'simple_addition' is deprecated and will be removed in future release 1.3.0."
        "\nWith some reason message."
    )
    simple_addition(a=1)
    warn_obj = recwarn.pop(DeprecationWarning)
    assert str(warn_obj.message) == warn_msg_expected