Springboot test controller via WebClient instead of WebTestClient - spring

Question

I'm attempting something perhaps misguided but please help.
I would like to test springboot controller via #WebFluxTest. However I would like to use WebClient instead of WebTestClient. How can this be done?
So far, I managed to use reflection to get ExchangeFunction out of WebTestClient and assign it to WebClient - and it works! Calls are made, controller responds - wonderful. However I don't think this is good approach. Is there a better way?
Thank you.

Answer 1

Ideally, you should use a WebTestClient which is more of a convenience wrapper around the WebClient. Just like the TestRestTemplate is for a RestTemplate. Both allow a request to be created and you can easily make assertions. They exist to make your test life easier.
If you really want to use a WebClient instead of a WebTestClient and do the assertions manually (which means you are probably complicating things) you can use the WebClient.Builder to create one. Spring Boot will automatically configure one and you can simply autowire it in your test and call the build method.
#SpringBootTest
public void YourTest {
#Autowired
private WebClient.Builder webClientBuilder;
#Test
public void doTest() {
WebClient webClient = webClientBuilder.build();
}
}
The same should work with #WebFluxTest as well.

Answer 2

Ok, after much experimentation here is a solution to test springboot controller & filters via a mocked connection - no webservice, no ports and quick test.
Unfortunately I didn't work out how to do it via #WebFluxTest and WebClient, instead MockMvc can be used to achieve desired result:
#ExtendWith(SpringExtension.class)
#Import({SomeDependencyService.class, SomeFilter.class})
#WebMvcTest(controllers = SomeController.class, excludeAutoConfiguration = SecurityAutoConfiguration.class)
#AutoConfigureMockMvc()
public class SomeControllerTest {
#MockBean
private SomeDependencyService someDependencyService;
#Autowired
private MockMvc mockMvc;
private SomeCustomizedClient subject;
#BeforeEach
public void setUp() {
subject = buildClient();
WebClient webClient = mockClientConnection();
subject.setWebClient(webClient);
}
private WebClient mockClientConnection() {
MockMvcHttpConnector mockMvcHttpConnector = new MockMvcHttpConnector(mockMvc);
WebClient webClient = WebClient.builder().clientConnector(mockMvcHttpConnector).build();
return webClient;
}
#Test
public void sample() {
when(SomeDependencyService.somePersistentOperation(any(), any())).thenReturn(new someDummyData());
SomeDeserializedObject actual = subject.someCallToControllerEndpoint("example param");
assertThat(actual.getData).isEquals("expected data");
}
}
Now it is possible to test your customized client (for example if you have internal java client that contains few important customization like security, etags, logging, de-serialization and uniform error handling) and associated controller (and filters if you #import them along) at the cost of a unit test.
You do NOT have to bring up entire service to verify the client and controller is working correctly.