Document that web clients are opt-in with @SpringBootTest

Closes gh-47891

Author: snicoll

documentation/spring-boot-docs/src/docs/antora/modules/reference/pages/testing/spring-boot-applications.adoc

@@ -178,16 +178,20 @@ If you use `@SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)`, an avai
 
 The javadoc:org.springframework.boot.test.web.server.LocalServerPort[format=annotation] annotation can be used to xref:how-to:webserver.adoc#howto.webserver.discover-port[inject the actual port used] into your test.
 
-For convenience, tests that need to make REST calls to the started server can additionally autowire a
-{url-spring-framework-docs}/testing/resttestclient.html[`RestTestClient`] which resolves relative links to the running server and comes with a dedicated API for verifying responses, as shown in the following example:
+Tests that need to make REST calls to the started server can autowire a
+{url-spring-framework-docs}/testing/resttestclient.html[`RestTestClient`] by annotating the test class with javadoc:org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient[format=annotation].
+
+The configured client resolves relative links to the running server and comes with a dedicated API for verifying responses, as shown in the following example:
 
 include-code::MyRandomPortRestTestClientTests[]
 
 If you prefer to use AssertJ, dedicated assertions are available from javadoc:org.springframework.test.web.servlet.client.assertj.RestTestClientResponse[], as shown in the following example:
 
 include-code::MyRandomPortRestTestClientAssertJTests[]
 
-If you have `spring-webflux` on the classpath, you can also autowire a {url-spring-framework-docs}/testing/webtestclient.html[`WebTestClient`] that provides a similar API:
+If you have `spring-webflux` on the classpath, you can also autowire a {url-spring-framework-docs}/testing/webtestclient.html[`WebTestClient`] by annotating the test class with javadoc:org.springframework.boot.webtestclient.AutoConfigureWebTestClient[format=annotation].
+
+`WebTestClient` provides a similar API, as shown in the following example:
 
 include-code::MyRandomPortWebTestClientTests[]
 
@@ -387,6 +391,7 @@ Often, javadoc:org.springframework.boot.webflux.test.autoconfigure.WebFluxTest[f
 javadoc:org.springframework.boot.webflux.test.autoconfigure.WebFluxTest[format=annotation] also auto-configures {url-spring-framework-docs}/testing/webtestclient.html[`WebTestClient`], which offers a powerful way to quickly test WebFlux controllers without needing to start a full HTTP server.
 
 TIP: You can also auto-configure javadoc:org.springframework.test.web.reactive.server.WebTestClient[] in a non-`@WebFluxTest` (such as javadoc:org.springframework.boot.test.context.SpringBootTest[format=annotation]) by annotating it with javadoc:org.springframework.boot.webflux.test.autoconfigure.AutoConfigureWebTestClient[format=annotation].
+
 The following example shows a class that uses both javadoc:org.springframework.boot.webflux.test.autoconfigure.WebFluxTest[format=annotation] and a javadoc:org.springframework.test.web.reactive.server.WebTestClient[]:
 
 include-code::MyControllerTests[]

documentation/spring-boot-docs/src/docs/antora/modules/reference/pages/testing/test-utilities.adoc

@@ -62,8 +62,9 @@ javadoc:org.springframework.boot.resttestclient.TestRestTemplate[] can be instan
 
 include-code::MyTests[]
 
-Alternatively, if you use the javadoc:org.springframework.boot.test.context.SpringBootTest[format=annotation] annotation with `WebEnvironment.RANDOM_PORT` or `WebEnvironment.DEFINED_PORT`, you can inject a fully configured javadoc:org.springframework.boot.resttestclient.TestRestTemplate[] by by annotating your test class with javadoc:org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate[format=annotation] and start using it.
+Alternatively, if you use the javadoc:org.springframework.boot.test.context.SpringBootTest[format=annotation] annotation with `WebEnvironment.RANDOM_PORT` or `WebEnvironment.DEFINED_PORT`, you can inject a fully configured javadoc:org.springframework.boot.resttestclient.TestRestTemplate[] by annotating the test class with javadoc:org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate[format=annotation].
 If necessary, additional customizations can be applied through the javadoc:org.springframework.boot.web.client.RestTemplateBuilder[] bean.
+
 Any URLs that do not specify a host and port automatically connect to the embedded server, as shown in the following example:
 
 include-code::MySpringBootTests[]

documentation/spring-boot-docs/src/main/java/org/springframework/boot/docs/testing/springbootapplications/withmockenvironment/MyMockMvcTests.java

@@ -22,6 +22,7 @@
 import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc;
+import org.springframework.boot.webtestclient.AutoConfigureWebTestClient;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.assertj.MockMvcTester;
@@ -37,6 +38,7 @@
 @SpringBootTest
 @AutoConfigureMockMvc
 @AutoConfigureRestTestClient
+@AutoConfigureWebTestClient
 class MyMockMvcTests {
 
 	@Test

documentation/spring-boot-docs/src/main/java/org/springframework/boot/docs/testing/springbootapplications/withrunningserver/MyRandomPortTestRestTemplateTests.java

@@ -20,12 +20,14 @@
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.resttestclient.TestRestTemplate;
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureTestRestTemplate
 class MyRandomPortTestRestTemplateTests {
 
 	@Test

documentation/spring-boot-docs/src/main/java/org/springframework/boot/docs/testing/springbootapplications/withrunningserver/MyRandomPortWebTestClientTests.java

@@ -21,9 +21,11 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.webtestclient.AutoConfigureWebTestClient;
 import org.springframework.test.web.reactive.server.WebTestClient;
 
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureWebTestClient
 class MyRandomPortWebTestClientTests {
 
 	@Test

documentation/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/testing/springbootapplications/withmockenvironment/MyMockMvcTests.kt

@@ -22,6 +22,7 @@ import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient
 import org.springframework.boot.test.context.SpringBootTest
 import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc
+import org.springframework.boot.webtestclient.AutoConfigureWebTestClient
 import org.springframework.test.web.reactive.server.WebTestClient
 import org.springframework.test.web.reactive.server.expectBody
 import org.springframework.test.web.servlet.MockMvc
@@ -36,6 +37,7 @@ import org.springframework.test.web.servlet.result.MockMvcResultMatchers.status
 @SpringBootTest
 @AutoConfigureMockMvc
 @AutoConfigureRestTestClient
+@AutoConfigureWebTestClient
 class MyMockMvcTests {
 
 	@Test

documentation/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/testing/springbootapplications/withrunningserver/MyRandomPortTestRestTemplateTests.kt

@@ -22,8 +22,10 @@ import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.boot.test.context.SpringBootTest
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment
 import org.springframework.boot.resttestclient.TestRestTemplate
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate
 
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureTestRestTemplate
 class MyRandomPortTestRestTemplateTests {
 
 	@Test

documentation/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/testing/springbootapplications/withrunningserver/MyRandomPortWebTestClientTests.kt

@@ -20,10 +20,12 @@ import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.boot.test.context.SpringBootTest
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment
+import org.springframework.boot.webtestclient.AutoConfigureWebTestClient
 import org.springframework.test.web.reactive.server.WebTestClient
 import org.springframework.test.web.reactive.server.expectBody
 
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureWebTestClient
 class MyRandomPortWebTestClientTests {
 
 	@Test