}

    @ParameterizedTest(name = "send with single param: {0}")
    @EnumSource(RequestParam.class)
    @DisplayName("send handles each RequestParam enum constant")
    void send_eachRequestParam_isAccepted(RequestParam param) throws Exception {
        // Arrange: stub per-call return to ensure interaction with the exact enum
        when(tree.send(eq(request), eq(param))).thenReturn(response);

        // Act