Do you know netflix feign? No? You should!
In short, feign is a quick and easy way to write a client for APIs. You can even use it to produce the client for your API easily!
What I like about it is:
-
compile time check
-
really easy to mock
If mocking feign clients is easy, testing the logic written in annotations is everything but!
To check if you are parsing the request/response properly the only way it firing a real request. Well, that doesn’t seem to be a good path to unit (or even integration) test remote services. Any IO change will affect test stability.
That is why I create feign-mock.
With feign-mock you can using pre-loaded json strings or streams as content for your responses. It also allow you to verify mock invokation and feign-mock will hit your annotations to make sure everything works.
Example
private GitHub github;
private MockClient mockClient;
@Before
public void setup() throws IOException {
mockClient = new MockClient()
.noContent(HttpMethod.PATCH, "/repos/velo/feign-mock/contributors");
github = Feign.builder()
.decoder(new GsonDecoder())
.client(mockClient)
.target(new MockTarget<>(GitHub.class));
}
@Test
public void missHttpMethod() {
List<Contributor> result = github.patchContributors("velo", "feign-mock");
assertThat(result, nullValue());
mockClient.verifyOne(HttpMethod.PATCH, "/repos/velo/feign-mock/contributors");
}This simple test returns no content and verify if the url was trully invoked.
On mock client, you can include all urls and methods you wanna mock.
For a more compreensive example take a look at MockClientTest.