如何在@WebMvcTest中获取Spring Boot默认验证响应？

Question

When I run my application and there is a validation problem with the request to one of my endpoints, the response has a lot of information on what exactly went wrong. It looks similar to this:

{
  "timestamp": "2017-11-23T13:18:05.923+0000",
  "status": 400,
  "error": "Bad Request",
  "exception": "org.springframework.web.bind.MethodArgumentNotValidException",
  "errors": [
    {
      "codes": [
        "Size.sensorParameters.openText",
        "Size.openText",
        "Size.java.lang.String",
        "Size"
      ],
      "arguments": [
        {
          "codes": [
            "sensorParameters.openText",
            "openText"
          ],
          "arguments": null,
          "defaultMessage": "openText",
          "code": "openText"
        },
        20,
        1
      ],
      "defaultMessage": "size must be between 1 and 20",
      "objectName": "sensorParameters",
      "field": "openText",
      "rejectedValue": "xewrewrwerwer weew ewewewrwe ew wewewewerew we ewrwerwe ewr ",
      "bindingFailure": false,
      "code": "Size"
    }
  ],
  "message": "Validation failed for object='sensorParameters'. Error count: 1",
  "path": "/api/monitors/89c94880-9423-4990-892b-6bbd8e90b1e6/sensors"
}

If I test this in an @WebMvcTest , I do get the same 400 response, but the response body is empty.

Is there some extra setup I should be doing in order to get the same behaviour in my unit test? I am using the @Autowired MockMvc object I get from the test framework without any extra setup from my side currently.

Answer 1

As Rossen Stoyanchev (the inventor of MockMvc ) pointed out in a related issue on JIRA ...

the body is taken care of by Spring Boot which configures error mappings at the Servlet container level (see here and since Spring MVC Test runs with a mock Servlet request/response, there is no such error mapping.

He goes on to advise that one use MockMvc to test controller logic and mappings, but that one write an in container integration with Spring Boot to test the error mapping support in the Servlet managed by Spring Boot.

If you feel that Spring Boot should somehow (magically) provide the error mapping support in conjunction with MockMvc , I'd suggest you raise an issue on GitHub against the Spring Boot project.