def test_warns(self):
        """
        Test that using parallel=True on a function that does not have parallel
        semantics warns.
        """
        arr_ty = types.Array(types.float64, 2, "C")
        with warnings.catch_warnings(record=True) as w:
            warnings.simplefilter("always", NumbaPerformanceWarning)
            njit((arr_ty, arr_ty), parallel=True)(unsupported_parfor)
        self.check_parfors_warning(w)

        Test that using parallel=True on a function that does not have parallel
        semantics warns.
        
numba/tests/test_debug.py