Spring RestTemplate invoking webservice with errors and analyze status code

Question

I designed a webservice to perform a task if request parameters are OK, or return 401 Unauthorized HTTP status code if request parameters are wrong or empty.

I'm using RestTemplate to perform a test and I'm able to verify the HTTP 200 OK status if the webservice replies with success. I am however unable to test for HTTP 401 error because RestTemplate itself throws an exception.

My test method is

@Test
public void testUnauthorized()
{
    Map<String, Object> params = new HashMap<String, Object>();
    ResponseEntity response = restTemplate.postForEntity(url, params, Map.class);
    Assert.assertEquals(HttpStatus.UNAUTHORIZED, response.getStatusCode());
    Assert.assertNotNull(response.getBody());
}

Exception log is

org.springframework.web.client.HttpClientErrorException: 401 Unauthorized
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:88)
at org.springframework.web.client.RestTemplate.handleResponseError(RestTemplate.java:533)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:489)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:447)
at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:318)

How I can test if webservice replies with a HTTP status code 401?

Answer 1

You need to implement ResponseErrorHandler in order to intercept response code, body, and header when you get non-2xx response codes from the service using rest template. Copy all the information you need, attach it to your custom exception and throw it so that you can catch it in your test.

public class CustomResponseErrorHandler implements ResponseErrorHandler {

    private ResponseErrorHandler errorHandler = new DefaultResponseErrorHandler();

    public boolean hasError(ClientHttpResponse response) throws IOException {
        return errorHandler.hasError(response);
    }

    public void handleError(ClientHttpResponse response) throws IOException {
        String theString = IOUtils.toString(response.getBody());
        CustomException exception = new CustomException();
        Map<String, Object> properties = new HashMap<String, Object>();
        properties.put("code", response.getStatusCode().toString());
        properties.put("body", theString);
        properties.put("header", response.getHeaders());
        exception.setProperties(properties);
        throw exception;
    }
}

Now what you need to do in your test is, set this ResponseErrorHandler in RestTemplate like,

RestTemplate restclient = new RestTemplate();
restclient.setErrorHandler(new CustomResponseErrorHandler());
try {
    POJO pojo = restclient.getForObject(url, POJO.class); 
} catch (CustomException e) {
    Assert.isTrue(e.getProperties().get("body")
                    .equals("bad response"));
    Assert.isTrue(e.getProperties().get("code").equals("400"));
    Assert.isTrue(((HttpHeaders) e.getProperties().get("header"))
                    .get("fancyheader").toString().equals("[nilesh]"));
}