我正在测试一个方法中的返回值，但是还需要测试异常。下面是其中一个异常的代码片段-我应该如何测试它？

@Override
    public Response generateResponse(Request request) throws CustomException {           

        try {
            GenerateResponse response = client.generateResponse(headers, generateRequest);
            return response;
        } catch (FeignException.BadRequest badRequest) {
          String message = "Received Bad Request";
            throw new CustomException(message, "" + badRequest.status());
        } catch (FeignException.Unauthorized unauthorized) {
            log.error(unauthorized.contentUTF8());
            String message = "Received UnAuthorized Exception ";
            throw new CustomException(message, "" + unauthorized.status());
        } 
}}

我已经使用以下代码测试了我正在测试的方法的快乐路径：

Mockito.when(service.getResponse(Mockito.any(), Mockito.any())).thenReturn(getResponse);