unit testing - Unable to Mock Glassfish Jersey Client response object

Question

I am having problems with creating a mock Response object to use with my unit tests. I am using org.glassfish.jersey.core.jersey-client version 2.3.1 to implement my RESTful client and mockito version 1.9.5 to help me with mock objects. Here is my test's code:

@Test
public void testGetAll() throws IOException {
    // Given
    String expectedResource = "expectedResource"

    final Response expectedRes =  Response.ok(expectedResource, MediaType.APPLICATION_JSON).build();
    String receivedResource;

    BDDMockito.given(this.client.getSimpleClient().getAllWithResponse()).willReturn(expectedRes);

    // When
    receivedResource = this.client.getAll();

    // Then
    Assert.assertNotNull("Request constructed correctly and response received.", receivedResource);
    Assert.assertEquals("Resource is equal to expected.", expectedResource, receivedResource);
}

The problem occurs when this.client.getAll(); is executed. Here is that method's code:

public String getAll() throws GenericAragornException, ProcessingException{
    Response response = this.simpleClient.getAllWithResponse();

    if (response.getStatus() != 200) {
        processErrorResponse(response);
    }

    String entity = response.readEntity(String.class);

    // No errors so return entity converted to resourceType.
    return entity;
}

Note that I am mocking the this.simpleClient.getAllWithResponse() method with the manually created Response. When it reaches the response.readEntity(resourceListType); instruction, Jersey throws the following exception: java.lang.IllegalStateException - Method not supported on an outbound message.. After lots of research and debugging, it turns that, for some reason, when I create a Response using the response builder such as Response.ok(expectedResource, MediaType.APPLICATION_JSON).build(); it creates it as an OutboundResponse instead of as an InboundResponse. The latter are the only ones permitted to use the Response.readEntity() method. If it is an OutboundResponse, the exception is thrown.

However, I could not find any way of converting the manually created response to an InboundResponse. So my tests are doomed :(. Do you guys/gals have any idea of what I can do here? I don't want to mock the Response object with Mockito because I think it could be a code smell since it violates the Law of Demeter. Sincerely I am out of ideas here. Things like this should be simple and straightforward.

Answer 1

You can also mock response with Mockito:

final Response response = Mockito.mock(Response.class);
Mockito.when(response.getStatus()).thenReturn(responseStatus);
Mockito.when(response.readEntity(Mockito.any(Class.class))).thenReturn(responseEntity);
Mockito.when(response.readEntity(Mockito.any(GenericType.class))).thenReturn(responseEntity);

responseStatus is status code associated with the response and responseEnitty is of course entity you want to return. You can use that mock as a return statment in Mockito (e.g. ... thenReturn(response)).

In my projects I create builders for different types for mocks (in that case Response), so I can easly on demand build required mocks, e.g. Response with status code 200 and some custom entity attached.