Use RestClient in Spring MVC integration tests

Closes gh-45711

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/web/servlet/WebMvcEndpointChildContextConfigurationIntegrationTests.java

@@ -22,14 +22,12 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.function.Consumer;
-import java.util.function.Function;
 
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotEmpty;
 import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
-import reactor.core.publisher.Mono;
 
 import org.springframework.boot.actuate.autoconfigure.endpoint.EndpointAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointAutoConfiguration;
@@ -56,8 +54,8 @@
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.ResponseBody;
-import org.springframework.web.reactive.function.client.ClientResponse;
-import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.RequestHeadersSpec.ExchangeFunction;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -86,12 +84,11 @@ class WebMvcEndpointChildContextConfigurationIntegrationTests {
 
 	@Test // gh-17938
 	void errorEndpointIsUsedWithEndpoint() {
-		this.runner.run(withWebTestClient((client) -> {
+		this.runner.run(withRestClient((client) -> {
 			Map<String, ?> body = client.get()
 				.uri("actuator/fail")
 				.accept(MediaType.APPLICATION_JSON)
-				.exchangeToMono(toResponseBody())
-				.block();
+				.exchange(toResponseBody());
 			assertThat(body).hasEntrySatisfying("exception",
 					(value) -> assertThat(value).asString().contains("IllegalStateException"));
 			assertThat(body).hasEntrySatisfying("message",
@@ -102,12 +99,11 @@ void errorEndpointIsUsedWithEndpoint() {
 	@Test
 	void errorPageAndErrorControllerIncludeDetails() {
 		this.runner.withPropertyValues("server.error.include-stacktrace=always", "server.error.include-message=always")
-			.run(withWebTestClient((client) -> {
+			.run(withRestClient((client) -> {
 				Map<String, ?> body = client.get()
 					.uri("actuator/fail")
 					.accept(MediaType.APPLICATION_JSON)
-					.exchangeToMono(toResponseBody())
-					.block();
+					.exchange(toResponseBody());
 				assertThat(body).hasEntrySatisfying("message",
 						(value) -> assertThat(value).asString().contains("Epic Fail"));
 				assertThat(body).hasEntrySatisfying("trace",
@@ -117,12 +113,11 @@ void errorPageAndErrorControllerIncludeDetails() {
 
 	@Test
 	void errorEndpointIsUsedWithRestControllerEndpoint() {
-		this.runner.run(withWebTestClient((client) -> {
+		this.runner.run(withRestClient((client) -> {
 			Map<String, ?> body = client.get()
 				.uri("actuator/failController")
 				.accept(MediaType.APPLICATION_JSON)
-				.exchangeToMono(toResponseBody())
-				.block();
+				.exchange(toResponseBody());
 			assertThat(body).hasEntrySatisfying("exception",
 					(value) -> assertThat(value).asString().contains("IllegalStateException"));
 			assertThat(body).hasEntrySatisfying("message",
@@ -132,13 +127,12 @@ void errorEndpointIsUsedWithRestControllerEndpoint() {
 
 	@Test
 	void errorEndpointIsUsedWithRestControllerEndpointOnBindingError() {
-		this.runner.run(withWebTestClient((client) -> {
+		this.runner.run(withRestClient((client) -> {
 			Map<String, ?> body = client.post()
 				.uri("actuator/failController")
-				.bodyValue(Collections.singletonMap("content", ""))
+				.body(Collections.singletonMap("content", ""))
 				.accept(MediaType.APPLICATION_JSON)
-				.exchangeToMono(toResponseBody())
-				.block();
+				.exchange(toResponseBody());
 			assertThat(body).hasEntrySatisfying("exception",
 					(value) -> assertThat(value).asString().contains("MethodArgumentNotValidException"));
 			assertThat(body).hasEntrySatisfying("message",
@@ -150,12 +144,12 @@ void errorEndpointIsUsedWithRestControllerEndpointOnBindingError() {
 
 	@Test
 	void whenManagementServerBasePathIsConfiguredThenEndpointsAreBeneathThatPath() {
-		this.runner.withPropertyValues("management.server.base-path:/manage").run(withWebTestClient((client) -> {
+		this.runner.withPropertyValues("management.server.base-path:/manage").run(withRestClient((client) -> {
 			String body = client.get()
 				.uri("manage/actuator/success")
 				.accept(MediaType.APPLICATION_JSON)
-				.exchangeToMono((response) -> response.bodyToMono(String.class))
-				.block();
+				.retrieve()
+				.body(String.class);
 			assertThat(body).isEqualTo("Success");
 		}));
 	}
@@ -182,16 +176,16 @@ private void addConfigTreePropertySource(ConfigurableApplicationContext applicat
 		}
 	}
 
-	private ContextConsumer<AssertableWebApplicationContext> withWebTestClient(Consumer<WebClient> webClient) {
+	private ContextConsumer<AssertableWebApplicationContext> withRestClient(Consumer<RestClient> restClient) {
 		return (context) -> {
 			String port = context.getEnvironment().getProperty("local.management.port");
-			WebClient client = WebClient.create("http://localhost:" + port);
-			webClient.accept(client);
+			RestClient client = RestClient.create("http://localhost:" + port);
+			restClient.accept(client);
 		};
 	}
 
-	private Function<ClientResponse, ? extends Mono<Map<String, ?>>> toResponseBody() {
-		return ((clientResponse) -> clientResponse.bodyToMono(new ParameterizedTypeReference<Map<String, ?>>() {
+	private ExchangeFunction<Map<String, ?>> toResponseBody() {
+		return ((request, response) -> response.bodyTo(new ParameterizedTypeReference<Map<String, ?>>() {
 		}));
 	}