Polish "Add JUnit 4 and the Vintage Engine sample"

See gh-17100

spring-boot-samples/spring-boot-sample-junit-vintage/pom.xml

@@ -23,28 +23,6 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
-			<exclusions>
-				<exclusion>
-					<groupId>org.junit.jupiter</groupId>
-					<artifactId>junit-jupiter</artifactId>
-				</exclusion>
-				<exclusion>
-					<groupId>org.mockito</groupId>
-					<artifactId>mockito-junit-jupiter</artifactId>
-				</exclusion>
-			</exclusions>
 		</dependency>
 	</dependencies>
-	<build>
-		<plugins>
-			<plugin>
-				<groupId>org.springframework.boot</groupId>
-				<artifactId>spring-boot-maven-plugin</artifactId>
-			</plugin>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-surefire-plugin</artifactId>
-			</plugin>
-		</plugins>
-	</build>
 </project>

spring-boot-samples/spring-boot-sample-junit-vintage/src/main/java/sample/MessageController.java

@@ -20,7 +20,7 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
-public class MessageController {
+class MessageController {
 
 	@GetMapping("/hi")
 	public String hello() {

spring-boot-samples/spring-boot-sample-junit-vintage/src/test/java/sample/SampleJunitVintageApplicationTests.java

@@ -20,24 +20,23 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 
 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.test.web.client.TestRestTemplate;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
 import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
 
-import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
 
 @RunWith(SpringRunner.class)
-@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@WebMvcTest
 public class SampleJunitVintageApplicationTests {
 
 	@Autowired
-	private TestRestTemplate restTemplate;
+	private MockMvc mockMvc;
 
 	@Test
-	public void testMessage() {
-		String message = this.restTemplate.getForObject("/hi", String.class);
-		assertThat(message).isEqualTo("Hello World");
+	public void testMessage() throws Exception {
+		this.mockMvc.perform(get("/hi")).andExpect(content().string("Hello World"));
 	}
 
 }