How to unit test a Handler<RoutingContext> in Vert.x?

Question

I have :

Router.router(vertx).route().handler(new Handler<RoutingContext>() {
    @Override
    public void handle(RoutingContext event) {
        HttpServerRequest request = event.request();
        Buffer body = event.getBody();
        HttpServerResponse response = event.response();
        // Some code to test
        response.setStatusCode(200);
        response.end();
    }
});

How to unit test this by giving prepared request and body, and by inspecting the response ?

Answer 1

Usually testing such end points is more an integration-test rather than a unit test. No need to mock everything. mocking is meant for testing some external services which is not available at your test context. here is a sample to do an integration test with vert.x :

@ExtendWith(VertxExtension.class)
class IntegrationTest {
private static RequestSpecification requestSpecification;

  @BeforeAll
  static void prepareSpec() {
    requestSpecification = new RequestSpecBuilder()
      .addFilters(asList(new ResponseLoggingFilter(), new RequestLoggingFilter()))
      .setBaseUri("http://localhost:3002/")// Depends on your verticle config.
      .build();
  }

@BeforeEach
  void setup(Vertx vertx, VertxTestContext testContext) {

    vertx
        .deployVerticle(new MyVerticle(), 
                ar -> {
                    if(ar.succeeded()) {
                        testContext.completeNow();
                    } else {
                        testContext.failNow(ar.cause());
                    }
                }
        );
  }

@Test
  @DisplayName("Test message")
  void test() {
    JsonObject body = new JsonObject();//Fill it as you want

    given(requestSpecification)
      .contentType(ContentType.JSON)
      .body(body.encode())
      .post("/yourreqest")//Your resource path
      .then()
      .assertThat()
      .statusCode(200);//expected status
}

Answer 2

The unit to be tested here is your implementation of Handler .

So change the anonymous class to (at least) a (non private ) static inner class .

class MyHandler implements Handler<RoutingContext> {
    @Override
    public void handle(RoutingContext event) {
        HttpServerRequest request = event.request();
        Buffer body = event.getBody();
        HttpServerResponse response = event.response();
        // Some code to test
        response.setStatusCode(200);
        response.end();
    }
};

Router.router(vertx).route().handler(new MyHandler());

Then you can create an instance of your Handlre for testing an pass in a mock as context returning mocks for request and response .

@ExtendWith(MockitoExtension.class)
@RunWith(JUnitPlatform.class)
class MyHandlerTest {
   @Mock
   RoutingContext event;

   @Mock
   HttpServerRequest request;

   @Mock
   HttpServerResponse response;

   @BeforeEach
   public void setup(){
     doReturn(request).when(event).getRequest();
     doReturn(response).when(event)event.response();
  }

  @Test
  public void shouldSetStatusTo200whenNoError(){
    // arrange
    doReturn(SOME_VALID_BODY).when(request).getBody();
    // act
    new MyHandler().handle(event);
    // assert
    Mockito.verify(response).setStatusCode(200);
  }
}