Streaming Responses

The best way to test streaming responses such as Server-Sent Events is through the [WebTestClient] which can be used as a test client to connect to a MockMvc instance to perform tests on Spring MVC controllers without a running server. For example:

Java

WebTestClient client = MockMvcWebTestClient.bindToController(new SseController()).build();

FluxExchangeResult<Person> exchangeResult = client.get()
		.uri("/persons")
		.exchange()
		.expectStatus().isOk()
		.expectHeader().contentType("text/event-stream")
		.returnResult(Person.class);

// Use StepVerifier from Project Reactor to test the streaming response

StepVerifier.create(exchangeResult.getResponseBody())
		.expectNext(new Person("N0"), new Person("N1"), new Person("N2"))
		.expectNextCount(4)
		.consumeNextWith(person -> assertThat(person.getName()).endsWith("7"))
		.thenCancel()
		.verify();

WebTestClient can also connect to a live server and perform full end-to-end integration tests. This is also supported in Spring Boot where you can test a running server.