Migrate to MockRestServiceServer

Migrate `RestClientTestWithoutJacksonIntegrationTests` to use
Spring's `MockRestServiceServer`.

See gh-17491

Author: dreis2211

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/client/RestClientTestWithoutJacksonIntegrationTests.java

@@ -17,15 +17,18 @@
 package org.springframework.boot.test.autoconfigure.web.client;
 
 import org.junit.Test;
-import org.junit.runner.JUnitCore;
-import org.junit.runner.Result;
 import org.junit.runner.RunWith;
 
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.testsupport.runner.classpath.ClassPathExclusions;
 import org.springframework.boot.testsupport.runner.classpath.ModifiedClassPathRunner;
+import org.springframework.http.MediaType;
+import org.springframework.test.web.client.MockRestServiceServer;
 import org.springframework.util.ClassUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
+import static org.springframework.test.web.client.response.MockRestResponseCreators.withSuccess;
 
 /**
  * Tests for {@link RestClientTest @RestClientTest} without Jackson.
@@ -34,15 +37,21 @@
  */
 @RunWith(ModifiedClassPathRunner.class)
 @ClassPathExclusions("jackson-*.jar")
+@RestClientTest(ExampleRestClient.class)
 public class RestClientTestWithoutJacksonIntegrationTests {
 
+	@Autowired
+	private MockRestServiceServer server;
+
+	@Autowired
+	private ExampleRestClient client;
+
 	@Test
 	public void restClientTestCanBeUsedWhenJacksonIsNotOnTheClassPath() {
-		assertThat(ClassUtils.isPresent("com.fasterxml.jackson.databind.Module", getClass().getClassLoader()))
-				.isFalse();
-		Result result = JUnitCore.runClasses(RestClientTestWithComponentIntegrationTests.class);
-		assertThat(result.getFailureCount()).isEqualTo(0);
-		assertThat(result.getRunCount()).isGreaterThan(0);
+		ClassLoader classLoader = getClass().getClassLoader();
+		assertThat(ClassUtils.isPresent("com.fasterxml.jackson.databind.Module", classLoader)).isFalse();
+		this.server.expect(requestTo("/test")).andRespond(withSuccess("hello", MediaType.TEXT_HTML));
+		assertThat(this.client.test()).isEqualTo("hello");
 	}
 
 }