Validate our own tests work with JUnit5 and the vintage engine

Closes gh-14737

Co-authored-by: Stephane Nicoll <snicoll@pivotal.io>

spring-boot-samples/spring-boot-sample-jpa/src/test/java/sample/jpa/SampleJpaApplicationTests.java

@@ -16,13 +16,11 @@
 
 package sample.jpa;
 
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.context.web.WebAppConfiguration;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
@@ -38,23 +36,22 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  * @author Oliver Gierke
  * @author Dave Syer
  */
-@RunWith(SpringRunner.class)
 @SpringBootTest
 @WebAppConfiguration
-public class SampleJpaApplicationTests {
+class SampleJpaApplicationTests {
 
 	@Autowired
 	private WebApplicationContext context;
 
 	private MockMvc mvc;
 
-	@Before
+	@BeforeEach
 	public void setUp() {
 		this.mvc = MockMvcBuilders.webAppContextSetup(this.context).build();
 	}
 
 	@Test
-	public void testHome() throws Exception {
+	void testHome() throws Exception {
 		this.mvc.perform(get("/")).andExpect(status().isOk())
 				.andExpect(xpath("//tbody/tr").nodeCount(4));
 	}

spring-boot-samples/spring-boot-sample-jpa/src/test/java/sample/jpa/repository/JpaNoteRepositoryIntegrationTests.java

@@ -17,13 +17,11 @@ package sample.jpa.repository;
 
 import java.util.List;
 
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.junit.jupiter.api.Test;
 import sample.jpa.domain.Note;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.transaction.annotation.Transactional;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -33,16 +31,15 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Andy Wilkinson
  */
-@RunWith(SpringRunner.class)
 @SpringBootTest
 @Transactional
-public class JpaNoteRepositoryIntegrationTests {
+class JpaNoteRepositoryIntegrationTests {
 
 	@Autowired
 	JpaNoteRepository repository;
 
 	@Test
-	public void findsAllNotes() {
+	void findsAllNotes() {
 		List<Note> notes = this.repository.findAll();
 		assertThat(notes).hasSize(4);
 		for (Note note : notes) {

spring-boot-samples/spring-boot-sample-jpa/src/test/java/sample/jpa/repository/JpaTagRepositoryIntegrationTests.java

@@ -17,13 +17,11 @@ package sample.jpa.repository;
 
 import java.util.List;
 
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.junit.jupiter.api.Test;
 import sample.jpa.domain.Tag;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.transaction.annotation.Transactional;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -33,16 +31,15 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Andy Wilkinson
  */
-@RunWith(SpringRunner.class)
 @SpringBootTest
 @Transactional
-public class JpaTagRepositoryIntegrationTests {
+class JpaTagRepositoryIntegrationTests {
 
 	@Autowired
 	JpaTagRepository repository;
 
 	@Test
-	public void findsAllTags() {
+	void findsAllTags() {
 		List<Tag> tags = this.repository.findAll();
 		assertThat(tags).hasSize(3);
 		for (Tag tag : tags) {