title: Cant autowire `WebTestClient` - no auto configuration
body: <p>We are using spring framework 5 and spring boot 2.0.0.M6 and we are also using <code>WebClient</code> for reactive programming. We created test methods for our reactive rest endpoints and so I looked up for some example on how to do it. I found <a href="https://github.com/spring-projects/spring-boot/blob/master/spring-boot-samples/spring-boot-sample-webflux/src/test/java/sample/webflux/SampleWebFluxApplicationTests.java" rel="noreferrer">this</a> one or <a href="https://www.callicoder.com/spring-5-reactive-webclient-webtestclient-examples/" rel="noreferrer">this</a> and many others which where all the same. They just autowire a <code>WebTestClient</code>. So I tried the same:</p>
  
  <pre><code>@Log
  @RunWith(SpringRunner.class)
  @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
  public class MyControllerTest {
  
      @Autowired
      private WebTestClient webClient;
  
      @Test
      public void getItems() throws Exception {
          log.info("Test: '/items/get'");
  
          Parameters params = new Parameters("#s23lkjslökjh12", "2015-09-20/2015-09-27");
  
          this.webClient.post().uri("/items/get")
                  .accept(MediaType.APPLICATION_STREAM_JSON)
                  .contentType(MediaType.APPLICATION_STREAM_JSON)
                  .body(BodyInserters.fromPublisher(Mono.just(params), Parameters.class))
                  .exchange()
                  .expectStatus().isOk()
                  .expectHeader().contentType(MediaType.APPLICATION_STREAM_JSON)
                  .expectBody(Basket.class);
      }
  }
  </code></pre>
  
  <p>I cannot run this because I get the error:</p>
  
  <pre><code>Could not autowire. No beans of 'WebTestClient' type found.
  </code></pre>
  
  <p>So it does not seem that there is a auto configuration existing. Do I use the wrong version or what is the matter here?</p>