Minor improvements in spring-test

- Remove final modifier from private method
- Use StandardCharsets
- Remove unnecessary toString calls
- Remove unnecessary static modifiers
- Refactor to use enhanced switch
- Replace concatenated strings with text blocks
- Rely on auto-boxing where appropriate
- Remove unnecessary code
- Fix imports in Kotlin test classes

Closes gh-29413

spring-test/src/main/java/org/springframework/test/context/junit/jupiter/AbstractExpressionEvaluatingCondition.java

@@ -93,7 +93,7 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 		AnnotatedElement element = context.getElement().get();
 		Optional<A> annotation = findMergedAnnotation(element, annotationType);
 
-		if (!annotation.isPresent()) {
+		if (annotation.isEmpty()) {
 			String reason = String.format("%s is enabled since @%s is not present", element,
 					annotationType.getSimpleName());
 			if (logger.isDebugEnabled()) {

spring-test/src/main/java/org/springframework/test/context/support/AbstractGenericContextLoader.java

@@ -188,7 +188,7 @@ public abstract class AbstractGenericContextLoader extends AbstractContextLoader
 	 * register a JVM shutdown hook for it
 	 * @return a new application context
 	 */
-	private final GenericApplicationContext loadContext(
+	private GenericApplicationContext loadContext(
 			MergedContextConfiguration mergedConfig, boolean forAotProcessing) throws Exception {
 
 		if (logger.isTraceEnabled()) {

spring-test/src/main/java/org/springframework/test/context/testng/AbstractTestNGSpringContextTests.java

@@ -201,7 +201,7 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	private Throwable getTestResultException(ITestResult testResult) {
 		Throwable testResultException = testResult.getThrowable();
 		if (testResultException instanceof InvocationTargetException) {
-			testResultException = ((InvocationTargetException) testResultException).getCause();
+			testResultException = testResultException.getCause();
 		}
 		return testResultException;
 	}

spring-test/src/main/java/org/springframework/test/util/XmlExpectationsHelper.java

@@ -82,7 +82,7 @@ public class XmlExpectationsHelper {
 	public void assertXmlEqual(String expected, String actual) throws Exception {
 		XmlUnitDiff diff = new XmlUnitDiff(expected, actual);
 		if (diff.hasDifferences()) {
-			AssertionErrors.fail("Body content " + diff.toString());
+			AssertionErrors.fail("Body content " + diff);
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/context/configuration/interfaces/BootstrapWithTestInterface.java

@@ -34,7 +34,7 @@ import static java.util.Collections.singletonList;
 @BootstrapWith(CustomTestContextBootstrapper.class)
 interface BootstrapWithTestInterface {
 
-	static class CustomTestContextBootstrapper extends DefaultTestContextBootstrapper {
+	class CustomTestContextBootstrapper extends DefaultTestContextBootstrapper {
 
 		@Override
 		protected List<ContextCustomizerFactory> getContextCustomizerFactories() {

spring-test/src/test/java/org/springframework/test/context/configuration/interfaces/ContextConfigurationTestInterface.java

@@ -28,7 +28,7 @@ import org.springframework.test.context.configuration.interfaces.ContextConfigur
 @ContextConfiguration(classes = Config.class)
 interface ContextConfigurationTestInterface {
 
-	static class Config {
+	class Config {
 
 		@Bean
 		Employee employee() {

spring-test/src/test/java/org/springframework/test/context/configuration/interfaces/WebAppConfigurationTestInterface.java

@@ -30,7 +30,7 @@ import org.springframework.test.context.web.WebAppConfiguration;
 interface WebAppConfigurationTestInterface {
 
 	@Configuration
-	static class Config {
+	class Config {
 		/* no user beans required for these tests */
 	}
 

spring-test/src/test/java/org/springframework/test/context/junit4/annotation/meta/ConfigClassesAndProfileResolverWithCustomDefaultsMetaConfig.java

@@ -52,7 +52,7 @@ public @interface ConfigClassesAndProfileResolverWithCustomDefaultsMetaConfig {
 
 	@Configuration
 	@Profile("dev")
-	static class DevConfig {
+	class DevConfig {
 
 		@Bean
 		public String foo() {
@@ -62,7 +62,7 @@ public @interface ConfigClassesAndProfileResolverWithCustomDefaultsMetaConfig {
 
 	@Configuration
 	@Profile("prod")
-	static class ProductionConfig {
+	class ProductionConfig {
 
 		@Bean
 		public String foo() {
@@ -72,7 +72,7 @@ public @interface ConfigClassesAndProfileResolverWithCustomDefaultsMetaConfig {
 
 	@Configuration
 	@Profile("resolver")
-	static class ResolverConfig {
+	class ResolverConfig {
 
 		@Bean
 		public String foo() {
@@ -80,7 +80,7 @@ public @interface ConfigClassesAndProfileResolverWithCustomDefaultsMetaConfig {
 		}
 	}
 
-	static class CustomResolver implements ActiveProfilesResolver {
+	class CustomResolver implements ActiveProfilesResolver {
 
 		@Override
 		public String[] resolve(Class<?> testClass) {

spring-test/src/test/java/org/springframework/test/context/junit4/annotation/meta/ConfigClassesAndProfilesWithCustomDefaultsMetaConfig.java

@@ -50,7 +50,7 @@ public @interface ConfigClassesAndProfilesWithCustomDefaultsMetaConfig {
 
 	@Configuration
 	@Profile("dev")
-	static class DevConfig {
+	class DevConfig {
 
 		@Bean
 		public String foo() {
@@ -60,7 +60,7 @@ public @interface ConfigClassesAndProfilesWithCustomDefaultsMetaConfig {
 
 	@Configuration
 	@Profile("prod")
-	static class ProductionConfig {
+	class ProductionConfig {
 
 		@Bean
 		public String foo() {

spring-test/src/test/java/org/springframework/test/context/junit4/rules/ProgrammaticTxMgmtSpringRuleTests.java

@@ -97,24 +97,11 @@ public class ProgrammaticTxMgmtSpringRuleTests {
 	void afterTransaction() {
 		String method = this.testName.getMethodName();
 		switch (method) {
-			case "commitTxAndStartNewTx":
-			case "commitTxButDoNotStartNewTx": {
-				assertUsers("Dogbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTx":
-			case "rollbackTxButDoNotStartNewTx":
-			case "startTxWithExistingTransaction": {
-				assertUsers("Dilbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics": {
-				assertUsers("Dilbert", "Dogbert");
-				break;
-			}
-			default: {
-				fail("missing 'after transaction' assertion for test method: " + method);
-			}
+			case "commitTxAndStartNewTx", "commitTxButDoNotStartNewTx" -> assertUsers("Dogbert");
+			case "rollbackTxAndStartNewTx", "rollbackTxButDoNotStartNewTx", "startTxWithExistingTransaction" ->
+					assertUsers("Dilbert");
+			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics" -> assertUsers("Dilbert", "Dogbert");
+			default -> fail("missing 'after transaction' assertion for test method: " + method);
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/context/junit4/spr9051/AnnotatedConfigClassesWithoutAtConfigurationTests.java

@@ -94,7 +94,7 @@ public class AnnotatedConfigClassesWithoutAtConfigurationTests {
 		assertThat(lifecycleBean).isNotNull();
 		assertThat(lifecycleBean.isInitialized()).isTrue();
 		Set<String> names = new HashSet<>();
-		names.add(enigma.toString());
+		names.add(enigma);
 		names.add(lifecycleBean.getName());
 		assertThat(new HashSet<>(Arrays.asList("enigma #1", "enigma #2"))).isEqualTo(names);
 	}

spring-test/src/test/java/org/springframework/test/context/support/DelegatingSmartContextLoaderTests.java

@@ -219,7 +219,7 @@ class DelegatingSmartContextLoaderTests {
 
 			@Bean
 			public String foo() {
-				return new String("foo");
+				return "foo";
 			}
 		}
 

spring-test/src/test/java/org/springframework/test/context/testng/transaction/programmatic/ProgrammaticTxMgmtTestNGTests.java

@@ -73,24 +73,11 @@ public class ProgrammaticTxMgmtTestNGTests extends AbstractTransactionalTestNGSp
 	@AfterTransaction
 	public void afterTransaction() {
 		switch (this.methodName) {
-			case "commitTxAndStartNewTx":
-			case "commitTxButDoNotStartNewTx": {
-				assertUsers("Dogbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTx":
-			case "rollbackTxButDoNotStartNewTx":
-			case "startTxWithExistingTransaction": {
-				assertUsers("Dilbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics": {
-				assertUsers("Dilbert", "Dogbert");
-				break;
-			}
-			default: {
-				fail("missing 'after transaction' assertion for test method: " + this.methodName);
-			}
+			case "commitTxAndStartNewTx", "commitTxButDoNotStartNewTx" -> assertUsers("Dogbert");
+			case "rollbackTxAndStartNewTx", "rollbackTxButDoNotStartNewTx", "startTxWithExistingTransaction" ->
+					assertUsers("Dilbert");
+			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics" -> assertUsers("Dilbert", "Dogbert");
+			default -> fail("missing 'after transaction' assertion for test method: " + this.methodName);
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/context/transaction/programmatic/ProgrammaticTxMgmtTests.java

@@ -88,24 +88,11 @@ class ProgrammaticTxMgmtTests {
 	@AfterTransaction
 	void afterTransaction() {
 		switch (this.methodName) {
-			case "commitTxAndStartNewTx":
-			case "commitTxButDoNotStartNewTx": {
-				assertUsers("Dogbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTx":
-			case "rollbackTxButDoNotStartNewTx":
-			case "startTxWithExistingTransaction": {
-				assertUsers("Dilbert");
-				break;
-			}
-			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics": {
-				assertUsers("Dilbert", "Dogbert");
-				break;
-			}
-			default: {
-				fail("missing 'after transaction' assertion for test method: " + this.methodName);
-			}
+			case "commitTxAndStartNewTx", "commitTxButDoNotStartNewTx" -> assertUsers("Dogbert");
+			case "rollbackTxAndStartNewTx", "rollbackTxButDoNotStartNewTx", "startTxWithExistingTransaction" ->
+					assertUsers("Dilbert");
+			case "rollbackTxAndStartNewTxWithDefaultCommitSemantics" -> assertUsers("Dilbert", "Dogbert");
+			default -> fail("missing 'after transaction' assertion for test method: " + this.methodName);
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/util/ReflectionTestUtilsTests.java

@@ -46,7 +46,7 @@ import static org.springframework.test.util.ReflectionTestUtils.setField;
  */
 class ReflectionTestUtilsTests {
 
-	private static final Float PI = Float.valueOf((float) 22 / 7);
+	private static final Float PI = (float) 22 / 7;
 
 	private final Person person = new PersonEntity();
 
@@ -64,7 +64,7 @@ class ReflectionTestUtilsTests {
 	@Test
 	void setFieldWithNullTargetObject() throws Exception {
 		assertThatIllegalArgumentException()
-			.isThrownBy(() -> setField((Object) null, "id", Long.valueOf(99)))
+			.isThrownBy(() -> setField((Object) null, "id", 99L))
 			.withMessageStartingWith("Either targetObject or targetClass");
 	}
 
@@ -78,7 +78,7 @@ class ReflectionTestUtilsTests {
 	@Test
 	void setFieldWithNullTargetClass() throws Exception {
 		assertThatIllegalArgumentException()
-			.isThrownBy(() -> setField((Class<?>) null, "id", Long.valueOf(99)))
+			.isThrownBy(() -> setField((Class<?>) null, "id", 99L))
 			.withMessageStartingWith("Either targetObject or targetClass");
 	}
 
@@ -92,21 +92,21 @@ class ReflectionTestUtilsTests {
 	@Test
 	void setFieldWithNullNameAndNullType() throws Exception {
 		assertThatIllegalArgumentException()
-			.isThrownBy(() -> setField(person, null, Long.valueOf(99), null))
+			.isThrownBy(() -> setField(person, null, 99L, null))
 			.withMessageStartingWith("Either name or type");
 	}
 
 	@Test
 	void setFieldWithBogusName() throws Exception {
 		assertThatIllegalArgumentException()
-			.isThrownBy(() -> setField(person, "bogus", Long.valueOf(99), long.class))
+			.isThrownBy(() -> setField(person, "bogus", 99L, long.class))
 			.withMessageStartingWith("Could not find field 'bogus'");
 	}
 
 	@Test
 	void setFieldWithWrongType() throws Exception {
 		assertThatIllegalArgumentException()
-			.isThrownBy(() -> setField(person, "id", Long.valueOf(99), String.class))
+			.isThrownBy(() -> setField(person, "id", 99L, String.class))
 			.withMessageStartingWith("Could not find field");
 	}
 
@@ -135,17 +135,17 @@ class ReflectionTestUtilsTests {
 
 	private static void assertSetFieldAndGetFieldBehavior(Person person) {
 		// Set reflectively
-		setField(person, "id", Long.valueOf(99), long.class);
+		setField(person, "id", 99L, long.class);
 		setField(person, "name", "Tom");
-		setField(person, "age", Integer.valueOf(42));
+		setField(person, "age", 42);
 		setField(person, "eyeColor", "blue", String.class);
 		setField(person, "likesPets", Boolean.TRUE);
 		setField(person, "favoriteNumber", PI, Number.class);
 
 		// Get reflectively
-		assertThat(getField(person, "id")).isEqualTo(Long.valueOf(99));
+		assertThat(getField(person, "id")).isEqualTo(99L);
 		assertThat(getField(person, "name")).isEqualTo("Tom");
-		assertThat(getField(person, "age")).isEqualTo(Integer.valueOf(42));
+		assertThat(getField(person, "age")).isEqualTo(42);
 		assertThat(getField(person, "eyeColor")).isEqualTo("blue");
 		assertThat(getField(person, "likesPets")).isEqualTo(Boolean.TRUE);
 		assertThat(getField(person, "favoriteNumber")).isEqualTo(PI);
@@ -249,33 +249,33 @@ class ReflectionTestUtilsTests {
 
 	@Test
 	void invokeSetterMethodAndInvokeGetterMethodWithExplicitMethodNames() throws Exception {
-		invokeSetterMethod(person, "setId", Long.valueOf(1), long.class);
+		invokeSetterMethod(person, "setId", 1L, long.class);
 		invokeSetterMethod(person, "setName", "Jerry", String.class);
-		invokeSetterMethod(person, "setAge", Integer.valueOf(33), int.class);
+		invokeSetterMethod(person, "setAge", 33, int.class);
 		invokeSetterMethod(person, "setEyeColor", "green", String.class);
 		invokeSetterMethod(person, "setLikesPets", Boolean.FALSE, boolean.class);
-		invokeSetterMethod(person, "setFavoriteNumber", Integer.valueOf(42), Number.class);
+		invokeSetterMethod(person, "setFavoriteNumber", 42, Number.class);
 
 		assertThat(person.getId()).as("ID (protected method in a superclass)").isEqualTo(1);
 		assertThat(person.getName()).as("name (private method)").isEqualTo("Jerry");
 		assertThat(person.getAge()).as("age (protected method)").isEqualTo(33);
 		assertThat(person.getEyeColor()).as("eye color (package private method)").isEqualTo("green");
 		assertThat(person.likesPets()).as("'likes pets' flag (protected method for a boolean)").isFalse();
-		assertThat(person.getFavoriteNumber()).as("'favorite number' (protected method for a Number)").isEqualTo(Integer.valueOf(42));
+		assertThat(person.getFavoriteNumber()).as("'favorite number' (protected method for a Number)").isEqualTo(42);
 
-		assertThat(invokeGetterMethod(person, "getId")).isEqualTo(Long.valueOf(1));
+		assertThat(invokeGetterMethod(person, "getId")).isEqualTo(1L);
 		assertThat(invokeGetterMethod(person, "getName")).isEqualTo("Jerry");
-		assertThat(invokeGetterMethod(person, "getAge")).isEqualTo(Integer.valueOf(33));
+		assertThat(invokeGetterMethod(person, "getAge")).isEqualTo(33);
 		assertThat(invokeGetterMethod(person, "getEyeColor")).isEqualTo("green");
 		assertThat(invokeGetterMethod(person, "likesPets")).isEqualTo(Boolean.FALSE);
-		assertThat(invokeGetterMethod(person, "getFavoriteNumber")).isEqualTo(Integer.valueOf(42));
+		assertThat(invokeGetterMethod(person, "getFavoriteNumber")).isEqualTo(42);
 	}
 
 	@Test
 	void invokeSetterMethodAndInvokeGetterMethodWithJavaBeanPropertyNames() throws Exception {
-		invokeSetterMethod(person, "id", Long.valueOf(99), long.class);
+		invokeSetterMethod(person, "id", 99L, long.class);
 		invokeSetterMethod(person, "name", "Tom");
-		invokeSetterMethod(person, "age", Integer.valueOf(42));
+		invokeSetterMethod(person, "age", 42);
 		invokeSetterMethod(person, "eyeColor", "blue", String.class);
 		invokeSetterMethod(person, "likesPets", Boolean.TRUE);
 		invokeSetterMethod(person, "favoriteNumber", PI, Number.class);
@@ -287,9 +287,9 @@ class ReflectionTestUtilsTests {
 		assertThat(person.likesPets()).as("'likes pets' flag (protected method for a boolean)").isTrue();
 		assertThat(person.getFavoriteNumber()).as("'favorite number' (protected method for a Number)").isEqualTo(PI);
 
-		assertThat(invokeGetterMethod(person, "id")).isEqualTo(Long.valueOf(99));
+		assertThat(invokeGetterMethod(person, "id")).isEqualTo(99L);
 		assertThat(invokeGetterMethod(person, "name")).isEqualTo("Tom");
-		assertThat(invokeGetterMethod(person, "age")).isEqualTo(Integer.valueOf(42));
+		assertThat(invokeGetterMethod(person, "age")).isEqualTo(42);
 		assertThat(invokeGetterMethod(person, "eyeColor")).isEqualTo("blue");
 		assertThat(invokeGetterMethod(person, "likesPets")).isEqualTo(Boolean.TRUE);
 		assertThat(invokeGetterMethod(person, "favoriteNumber")).isEqualTo(PI);
@@ -349,7 +349,7 @@ class ReflectionTestUtilsTests {
 		assertThat(component.getText()).as("text").isNull();
 
 		// Simulate autowiring a configuration method
-		invokeMethod(component, "configure", Integer.valueOf(42), "enigma");
+		invokeMethod(component, "configure", 42, "enigma");
 		assertThat(component.getNumber()).as("number should have been configured").isEqualTo(Integer.valueOf(42));
 		assertThat(component.getText()).as("text should have been configured").isEqualTo("enigma");
 
@@ -380,14 +380,14 @@ class ReflectionTestUtilsTests {
 	@Test
 	void invokeMethodWithTooFewArguments() {
 		assertThatIllegalStateException()
-			.isThrownBy(() -> invokeMethod(component, "configure", Integer.valueOf(42)))
+			.isThrownBy(() -> invokeMethod(component, "configure", 42))
 			.withMessageStartingWith("Method not found");
 	}
 
 	@Test
 	void invokeMethodWithTooManyArguments() {
 		assertThatIllegalStateException()
-			.isThrownBy(() -> invokeMethod(component, "configure", Integer.valueOf(42), "enigma", "baz", "quux"))
+			.isThrownBy(() -> invokeMethod(component, "configure", 42, "enigma", "baz", "quux"))
 			.withMessageStartingWith("Method not found");
 	}
 
@@ -406,7 +406,7 @@ class ReflectionTestUtilsTests {
 
 	@Test // SPR-14363
 	void invokeMethodOnLegacyEntityWithSideEffectsInToString() {
-		invokeMethod(entity, "configure", Integer.valueOf(42), "enigma");
+		invokeMethod(entity, "configure", 42, "enigma");
 		assertThat(entity.getNumber()).as("number should have been configured").isEqualTo(Integer.valueOf(42));
 		assertThat(entity.getText()).as("text should have been configured").isEqualTo("enigma");
 	}

spring-test/src/test/java/org/springframework/test/web/client/MockRestServiceServerTests.java

@@ -183,9 +183,11 @@ public class MockRestServiceServerTests {
 		this.restTemplate.getForObject("/foo", Void.class);
 
 		assertThatThrownBy(() -> server1.verify(Duration.ofMillis(100))).hasMessage(
-				"Further request(s) expected leaving 1 unsatisfied expectation(s).\n" +
-						"1 request(s) executed:\n" +
-						"GET /foo, headers: [Accept:\"application/json, application/*+json\"]\n");
+				"""
+						Further request(s) expected leaving 1 unsatisfied expectation(s).
+						1 request(s) executed:
+						GET /foo, headers: [Accept:"application/json, application/*+json"]
+						""");
 
 		MockRestServiceServer server2 = builder.build();
 		server2.expect(requestTo("/foo")).andRespond(withSuccess());

spring-test/src/test/java/org/springframework/test/web/client/SimpleRequestExpectationManagerTests.java

@@ -55,8 +55,10 @@ public class SimpleRequestExpectationManagerTests {
 			this.manager.validateRequest(createRequest(GET, "/foo"));
 		}
 		catch (AssertionError error) {
-			assertThat(error.getMessage()).isEqualTo(("No further requests expected: HTTP GET /foo\n" +
-						"0 request(s) executed.\n"));
+			assertThat(error.getMessage()).isEqualTo(("""
+					No further requests expected: HTTP GET /foo
+					0 request(s) executed.
+					"""));
 		}
 	}
 
@@ -83,10 +85,12 @@ public class SimpleRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/bar"));
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
 				this.manager.validateRequest(createRequest(GET, "/baz")))
-			.withMessage("No further requests expected: HTTP GET /baz\n" +
-					"2 request(s) executed:\n" +
-					"GET /foo\n" +
-					"GET /bar\n");
+			.withMessage("""
+					No further requests expected: HTTP GET /baz
+					2 request(s) executed:
+					GET /foo
+					GET /bar
+					""");
 	}
 
 	@Test
@@ -96,8 +100,11 @@ public class SimpleRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/foo"));
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
 				this.manager.verify())
-			.withMessage("Further request(s) expected leaving 1 unsatisfied expectation(s).\n" +
-				"1 request(s) executed:\nGET /foo\n");
+			.withMessage("""
+					Further request(s) expected leaving 1 unsatisfied expectation(s).
+					1 request(s) executed:
+					GET /foo
+					""");
 	}
 
 	@Test
@@ -124,12 +131,14 @@ public class SimpleRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/bar"));
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
 				this.manager.validateRequest(createRequest(GET, "/foo")))
-			.withMessage("No further requests expected: HTTP GET /foo\n" +
-					"4 request(s) executed:\n" +
-					"GET /foo\n" +
-					"GET /bar\n" +
-					"GET /foo\n" +
-					"GET /bar\n");
+			.withMessage("""
+					No further requests expected: HTTP GET /foo
+					4 request(s) executed:
+					GET /foo
+					GET /bar
+					GET /foo
+					GET /bar
+					""");
 	}
 
 	@Test
@@ -141,10 +150,12 @@ public class SimpleRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/foo"));
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
 				this.manager.verify())
-			.withMessageContaining("3 request(s) executed:\n" +
-				"GET /foo\n" +
-				"GET /bar\n" +
-				"GET /foo\n");
+			.withMessageContaining("""
+					3 request(s) executed:
+					GET /foo
+					GET /bar
+					GET /foo
+					""");
 	}
 
 	@Test

spring-test/src/test/java/org/springframework/test/web/client/UnorderedRequestExpectationManagerTests.java

@@ -52,8 +52,10 @@ public class UnorderedRequestExpectationManagerTests {
 			this.manager.validateRequest(createRequest(GET, "/foo"));
 		}
 		catch (AssertionError error) {
-			assertThat(error.getMessage()).isEqualTo(("No further requests expected: HTTP GET /foo\n" +
-						"0 request(s) executed.\n"));
+			assertThat(error.getMessage()).isEqualTo(("""
+					No further requests expected: HTTP GET /foo
+					0 request(s) executed.
+					"""));
 		}
 	}
 
@@ -94,12 +96,14 @@ public class UnorderedRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/foo"));
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
 				this.manager.validateRequest(createRequest(GET, "/foo")))
-			.withMessage("No further requests expected: HTTP GET /foo\n" +
-				"4 request(s) executed:\n" +
-				"GET /bar\n" +
-				"GET /foo\n" +
-				"GET /bar\n" +
-				"GET /foo\n");
+			.withMessage("""
+					No further requests expected: HTTP GET /foo
+					4 request(s) executed:
+					GET /bar
+					GET /foo
+					GET /bar
+					GET /foo
+					""");
 	}
 
 	@Test
@@ -111,10 +115,12 @@ public class UnorderedRequestExpectationManagerTests {
 		this.manager.validateRequest(createRequest(GET, "/foo"));
 		assertThatExceptionOfType(AssertionError.class)
 				.isThrownBy(this.manager::verify)
-				.withMessageContaining("3 request(s) executed:\n" +
-						"GET /bar\n" +
-						"GET /foo\n" +
-						"GET /foo\n");
+				.withMessageContaining("""
+						3 request(s) executed:
+						GET /bar
+						GET /foo
+						GET /foo
+						""");
 	}
 
 

spring-test/src/test/java/org/springframework/test/web/reactive/server/samples/SoftAssertionTests.java

@@ -56,9 +56,10 @@ class SoftAssertionTests {
 										responseSpec -> responseSpec.expectBody(String.class).isEqualTo("bogus")
 								)
 				)
-				.withMessage("Multiple Exceptions (2):\n" +
-						"Status expected:<400 BAD_REQUEST> but was:<200 OK>\n" +
-						"Response body expected:<bogus> but was:<hello>");
+				.withMessage("""
+						Multiple Exceptions (2):
+						Status expected:<400 BAD_REQUEST> but was:<200 OK>
+						Response body expected:<bogus> but was:<hello>""");
 	}
 
 

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/DelegatingWebConnectionTests.java

@@ -17,6 +17,7 @@
 package org.springframework.test.web.servlet.htmlunit;
 
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 
 import com.gargoylesoftware.htmlunit.HttpWebConnection;
@@ -79,7 +80,7 @@ public class DelegatingWebConnectionTests {
 	@BeforeEach
 	public void setup() throws Exception {
 		request = new WebRequest(new URL("http://localhost/"));
-		WebResponseData data = new WebResponseData("".getBytes("UTF-8"), 200, "", Collections.emptyList());
+		WebResponseData data = new WebResponseData("".getBytes(StandardCharsets.UTF_8), 200, "", Collections.emptyList());
 		expectedResponse = new WebResponse(data, request, 100L);
 		webConnection = new DelegatingWebConnection(defaultConnection,
 				new DelegateWebConnection(matcher1, connection1), new DelegateWebConnection(matcher2, connection2));

spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java

@@ -414,7 +414,7 @@ class MockHttpServletRequestBuilderTests {
 
 	@Test
 	void body() throws IOException {
-		byte[] body = "Hello World".getBytes("UTF-8");
+		byte[] body = "Hello World".getBytes(StandardCharsets.UTF_8);
 		this.builder.content(body);
 
 		MockHttpServletRequest request = this.builder.buildRequest(this.servletContext);

spring-test/src/test/java/org/springframework/test/web/servlet/result/ContentResultMatchersTests.java

@@ -46,7 +46,7 @@ public class ContentResultMatchersTests {
 
 	@Test
 	public void string() throws Exception {
-		new ContentResultMatchers().string(new String(CONTENT.getBytes("UTF-8"))).match(getStubMvcResult(CONTENT));
+		new ContentResultMatchers().string(new String(CONTENT.getBytes(StandardCharsets.UTF_8))).match(getStubMvcResult(CONTENT));
 	}
 
 	@Test
@@ -57,7 +57,7 @@ public class ContentResultMatchersTests {
 
 	@Test
 	public void stringMatcher() throws Exception {
-		String content = new String(CONTENT.getBytes("UTF-8"));
+		String content = new String(CONTENT.getBytes(StandardCharsets.UTF_8));
 		new ContentResultMatchers().string(Matchers.equalTo(content)).match(getStubMvcResult(CONTENT));
 	}
 
@@ -69,7 +69,7 @@ public class ContentResultMatchersTests {
 
 	@Test
 	public void bytes() throws Exception {
-		new ContentResultMatchers().bytes(CONTENT.getBytes("UTF-8")).match(getStubMvcResult(CONTENT));
+		new ContentResultMatchers().bytes(CONTENT.getBytes(StandardCharsets.UTF_8)).match(getStubMvcResult(CONTENT));
 	}
 
 	@Test

spring-test/src/test/java/org/springframework/test/web/servlet/result/JsonPathResultMatchersTests.java

@@ -302,7 +302,7 @@ public class JsonPathResultMatchersTests {
 	public void prefixWithPayloadNotLongEnough() throws Exception {
 		MockHttpServletResponse response = new MockHttpServletResponse();
 		response.addHeader("Content-Type", "application/json");
-		response.getWriter().print(new String("test".getBytes("ISO-8859-1")));
+		response.getWriter().print(new String("test".getBytes(StandardCharsets.ISO_8859_1)));
 		StubMvcResult result =  new StubMvcResult(null, null, null, null, null, null, response);
 
 		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
@@ -312,7 +312,7 @@ public class JsonPathResultMatchersTests {
 	private StubMvcResult createPrefixedStubMvcResult(String jsonPrefix) throws Exception {
 		MockHttpServletResponse response = new MockHttpServletResponse();
 		response.addHeader("Content-Type", "application/json");
-		response.getWriter().print(jsonPrefix + new String(RESPONSE_CONTENT.getBytes("ISO-8859-1")));
+		response.getWriter().print(jsonPrefix + new String(RESPONSE_CONTENT.getBytes(StandardCharsets.ISO_8859_1)));
 		return new StubMvcResult(null, null, null, null, null, null, response);
 	}
 

spring-test/src/test/java/org/springframework/test/web/servlet/result/PrintingResultHandlerTests.java

@@ -17,6 +17,7 @@
 package org.springframework.test.web.servlet.result;
 
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -74,7 +75,7 @@ public class PrintingResultHandlerTests {
 		this.request.addHeader("header", "headerValue");
 		this.request.setCharacterEncoding("UTF-16");
 		String palindrome = "ablE was I ere I saw Elba";
-		byte[] bytes = palindrome.getBytes("UTF-16");
+		byte[] bytes = palindrome.getBytes(StandardCharsets.UTF_16);
 		this.request.setContent(bytes);
 		this.request.getSession().setAttribute("foo", "bar");
 
@@ -100,7 +101,7 @@ public class PrintingResultHandlerTests {
 		this.request.addHeader("header", "headerValue");
 		this.request.setCharacterEncoding("UTF-16");
 		String palindrome = "ablE was I ere I saw Elba";
-		byte[] bytes = palindrome.getBytes("UTF-16");
+		byte[] bytes = palindrome.getBytes(StandardCharsets.UTF_16);
 		this.request.setContent(bytes);
 
 		this.handler.handle(this.mvcResult);
@@ -124,7 +125,7 @@ public class PrintingResultHandlerTests {
 		this.request.addHeader("header", "headerValue");
 		this.request.setCharacterEncoding("UTF-16");
 		String palindrome = "ablE was I ere I saw Elba";
-		byte[] bytes = palindrome.getBytes("UTF-16");
+		byte[] bytes = palindrome.getBytes(StandardCharsets.UTF_16);
 		this.request.setContent(bytes);
 		this.request.setSession(Mockito.mock(HttpSession.class));
 
@@ -204,7 +205,7 @@ public class PrintingResultHandlerTests {
 	@Test
 	public void printRequestWithCharacterEncoding() throws Exception {
 		this.request.setCharacterEncoding("UTF-8");
-		this.request.setContent("text".getBytes("UTF-8"));
+		this.request.setContent("text".getBytes(StandardCharsets.UTF_8));
 
 		this.handler.handle(this.mvcResult);
 

spring-test/src/test/java/org/springframework/test/web/servlet/result/StatusResultMatchersTests.java

@@ -85,23 +85,12 @@ public class StatusResultMatchersTests {
 			response.setStatus(status.value());
 			MvcResult mvcResult = new StubMvcResult(request, null, null, null, null, null, response);
 			switch (status.series().value()) {
-				case 1:
-					this.matchers.is1xxInformational().match(mvcResult);
-					break;
-				case 2:
-					this.matchers.is2xxSuccessful().match(mvcResult);
-					break;
-				case 3:
-					this.matchers.is3xxRedirection().match(mvcResult);
-					break;
-				case 4:
-					this.matchers.is4xxClientError().match(mvcResult);
-					break;
-				case 5:
-					this.matchers.is5xxServerError().match(mvcResult);
-					break;
-				default:
-					fail("Unexpected range for status code value " + status);
+				case 1 -> this.matchers.is1xxInformational().match(mvcResult);
+				case 2 -> this.matchers.is2xxSuccessful().match(mvcResult);
+				case 3 -> this.matchers.is3xxRedirection().match(mvcResult);
+				case 4 -> this.matchers.is4xxClientError().match(mvcResult);
+				case 5 -> this.matchers.is5xxServerError().match(mvcResult);
+				default -> fail("Unexpected range for status code value " + status);
 			}
 		}
 	}

spring-test/src/test/java/org/springframework/test/web/servlet/samples/client/standalone/ExceptionHandlerTests.java

@@ -173,14 +173,11 @@ class ExceptionHandlerTests {
 
 		@GetMapping("/person/{name}")
 		Person get(@PathVariable String name) {
-			switch (name) {
-				case "Luke":
-					throw new IllegalArgumentException();
-				case "Leia":
-					throw new IllegalStateException();
-				default:
-					return new Person("Yoda");
-			}
+			return switch (name) {
+				case "Luke" -> throw new IllegalArgumentException();
+				case "Leia" -> throw new IllegalStateException();
+				default -> new Person("Yoda");
+			};
 		}
 
 		@ExceptionHandler

spring-test/src/test/java/org/springframework/test/web/servlet/samples/client/standalone/resultmatches/XpathAssertionTests.java

@@ -224,11 +224,12 @@ public class XpathAssertionTests {
 		@RequestMapping(value = "/blog.atom", method = {GET, HEAD})
 		@ResponseBody
 		public String listPublishedPosts() {
-			return "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n"
-					+ "<feed xmlns=\"http://www.w3.org/2005/Atom\">\r\n"
-					+ "  <title>Test Feed</title>\r\n"
-					+ "  <icon>https://www.example.com/favicon.ico</icon>\r\n"
-					+ "</feed>\r\n\r\n";
+			return """
+					<?xml version="1.0" encoding="UTF-8"?>
+					<feed xmlns="http://www.w3.org/2005/Atom">
+						<title>Test Feed</title>
+						<icon>https://www.example.com/favicon.ico</icon>
+					</feed>""".replaceAll("\n", "\r\n");
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/ExceptionHandlerTests.java

@@ -152,14 +152,11 @@ public class ExceptionHandlerTests {
 
 		@GetMapping("/person/{name}")
 		Person get(@PathVariable String name) {
-			switch (name) {
-				case "Luke":
-					throw new IllegalArgumentException();
-				case "Leia":
-					throw new IllegalStateException();
-				default:
-					return new Person("Yoda");
-			}
+			return switch (name) {
+				case "Luke" -> throw new IllegalArgumentException();
+				case "Leia" -> throw new IllegalStateException();
+				default -> new Person("Yoda");
+			};
 		}
 
 		@ExceptionHandler

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/MultipartControllerTests.java

@@ -70,18 +70,12 @@ class MultipartControllerTests {
 		byte[] json = "{\"name\":\"yeeeah\"}".getBytes(StandardCharsets.UTF_8);
 		MockMultipartFile jsonPart = new MockMultipartFile("json", "json", "application/json", json);
 
-		MockMultipartHttpServletRequestBuilder requestBuilder;
-		switch (url) {
-			case "/multipartfile":
-				requestBuilder = multipart(url).file(new MockMultipartFile("file", "orig", null, fileContent));
-				break;
-			case "/multipartfile-via-put":
-				requestBuilder = multipart(HttpMethod.PUT, url).file(new MockMultipartFile("file", "orig", null, fileContent));
-				break;
-			default:
-				requestBuilder = multipart(url).part(new MockPart("part", "orig", fileContent));
-				break;
-		}
+		MockMultipartHttpServletRequestBuilder requestBuilder = switch (url) {
+			case "/multipartfile" -> multipart(url).file(new MockMultipartFile("file", "orig", null, fileContent));
+			case "/multipartfile-via-put" ->
+					multipart(HttpMethod.PUT, url).file(new MockMultipartFile("file", "orig", null, fileContent));
+			default -> multipart(url).part(new MockPart("part", "orig", fileContent));
+		};
 
 		standaloneSetup(new MultipartController()).build()
 				.perform(requestBuilder.file(jsonPart))

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/resulthandlers/PrintingResultHandlerSmokeTests.java

@@ -68,7 +68,7 @@ public class PrintingResultHandlerSmokeTests {
 
 		System.out.println();
 		System.out.println("===============================================================");
-		System.out.println(writer.toString());
+		System.out.println(writer);
 	}
 
 

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/resultmatchers/ContentAssertionTests.java

@@ -79,10 +79,10 @@ public class ContentAssertionTests {
 	@Test
 	void contentAsBytes() throws Exception {
 		this.mockMvc.perform(get("/handle").accept(MediaType.TEXT_PLAIN))
-			.andExpect(content().bytes("Hello world!".getBytes("ISO-8859-1")));
+			.andExpect(content().bytes("Hello world!".getBytes(StandardCharsets.ISO_8859_1)));
 
 		this.mockMvc.perform(get("/handleUtf8"))
-			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes("UTF-8")));
+			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes(StandardCharsets.UTF_8)));
 	}
 
 	@Test
@@ -103,11 +103,11 @@ public class ContentAssertionTests {
 
 		this.mockMvc.perform(get("/handleUtf8"))
 			.andExpect(content().encoding("UTF-8"))
-			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes("UTF-8")));
+			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes(StandardCharsets.UTF_8)));
 
 		this.mockMvc.perform(get("/handleUtf8"))
 			.andExpect(content().encoding(StandardCharsets.UTF_8))
-			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes("UTF-8")));
+			.andExpect(content().bytes("\u3053\u3093\u306b\u3061\u306f\u4e16\u754c\uff01".getBytes(StandardCharsets.UTF_8)));
 	}
 
 

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/resultmatchers/XpathAssertionTests.java

@@ -228,11 +228,12 @@ public class XpathAssertionTests {
 		@RequestMapping(value="/blog.atom", method = { GET, HEAD })
 		@ResponseBody
 		public String listPublishedPosts() {
-			return "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n"
-					+ "<feed xmlns=\"http://www.w3.org/2005/Atom\">\r\n"
-					+ "  <title>Test Feed</title>\r\n"
-					+ "  <icon>https://www.example.com/favicon.ico</icon>\r\n"
-					+ "</feed>\r\n\r\n";
+			return """
+					<?xml version="1.0" encoding="UTF-8"?>
+					<feed xmlns="http://www.w3.org/2005/Atom">
+						<title>Test Feed</title>
+						<icon>https://www.example.com/favicon.ico</icon>
+					</feed>""".replaceAll("\n", "\r\n");
 		}
 	}
 

spring-test/src/test/kotlin/org/springframework/test/web/servlet/MockMvcExtensionsTests.kt

@@ -16,21 +16,27 @@
 
 package org.springframework.test.web.servlet
 
-import org.assertj.core.api.Assertions.*
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.hamcrest.CoreMatchers
-import org.hamcrest.Matcher
-import org.hamcrest.Matchers
 import org.junit.jupiter.api.Test
 import org.springframework.http.HttpMethod
 import org.springframework.http.HttpStatus
-import org.springframework.http.MediaType.*
+import org.springframework.http.MediaType.APPLICATION_ATOM_XML
+import org.springframework.http.MediaType.APPLICATION_JSON
+import org.springframework.http.MediaType.APPLICATION_XML
 import org.springframework.test.web.Person
 import org.springframework.test.web.servlet.setup.MockMvcBuilders
-import org.springframework.web.bind.annotation.*
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PathVariable
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.ResponseStatus
+import org.springframework.web.bind.annotation.RestController
 import org.springframework.web.servlet.ModelAndView
 import reactor.core.publisher.Mono
 import java.security.Principal
-import java.util.*
+import java.util.Locale
 
 /**
  * [MockMvc] DSL tests that verifies builder, actions and expect blocks.