Use method references and/or simplify lambda expressions

Author: sbrannen

junit-jupiter-params/src/main/java/org/junit/jupiter/params/ResolverFacade.java

@@ -414,7 +414,7 @@ else if (declarations.size() > 1) {
 		}
 		fields.stream() //
 				.filter(ModifierSupport::isFinal) //
-				.map(field -> "@Parameter field [%s] must not be declared as final".formatted(field)) //
+				.map("@Parameter field [%s] must not be declared as final"::formatted) //
 				.forEach(errors::add);
 	}
 

junit-platform-engine/src/main/java/org/junit/platform/engine/CompositeFilter.java

@@ -81,7 +81,7 @@ public String toString() {
 		// @formatter:off
 		return filters.stream()
 				.map(Object::toString)
-				.map(value -> "(%s)".formatted(value))
+				.map("(%s)"::formatted)
 				.collect(joining(" and "));
 		// @formatter:on
 	}

junit-platform-launcher/src/main/java/org/junit/platform/launcher/AbstractMethodFilter.java

@@ -51,7 +51,7 @@ protected Optional<Pattern> findMatchingPattern(@Nullable String methodName) {
 
 	protected @Nullable String getFullyQualifiedMethodNameFromDescriptor(TestDescriptor descriptor) {
 		return descriptor.getSource() //
-				.filter(source -> source instanceof MethodSource) //
+				.filter(MethodSource.class::isInstance) //
 				.map(methodSource -> getFullyQualifiedMethodNameWithoutParameters(((MethodSource) methodSource))) //
 				.orElse(null);
 	}

junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/EngineDiscoveryOrchestrator.java

@@ -164,12 +164,12 @@ private Map<TestEngine, EngineResultInfo> discoverSafely(LauncherDiscoveryReques
 
 			if (engineIsExcluded) {
 				logger.debug(() -> "Test discovery for engine '%s' was skipped due to an EngineFilter%s.".formatted(
-					testEngine.getId(), phase.map(it -> " in %s phase".formatted(it)).orElse("")));
+					testEngine.getId(), phase.map(" in %s phase"::formatted).orElse("")));
 				continue;
 			}
 
 			logger.debug(() -> "Discovering tests%s in engine '%s'.".formatted(
-				phase.map(it -> " during Launcher %s phase".formatted(it)).orElse(""), testEngine.getId()));
+				phase.map(" during Launcher %s phase"::formatted).orElse(""), testEngine.getId()));
 
 			EngineResultInfo engineResult = discoverEngineRoot(testEngine, request, issueCollector, uniqueIdCreator);
 			testEngineDescriptors.put(testEngine, engineResult);

jupiter-tests/src/test/java/org/junit/jupiter/api/AssertAllAssertionsTests.java

@@ -19,7 +19,6 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
 
 import java.io.IOException;
 import java.util.Collection;
@@ -109,8 +108,8 @@ void assertAllWithExecutablesThatThrowAssertionErrors() {
 		// @formatter:off
 		MultipleFailuresError multipleFailuresError = assertThrows(MultipleFailuresError.class, () ->
 			assertAll(
-				() -> fail(),
-				() -> fail()
+				Assertions::fail,
+				Assertions::fail
 			)
 		);
 		// @formatter:on
@@ -123,8 +122,8 @@ void assertAllWithCollectionOfExecutablesThatThrowAssertionErrors() {
 		// @formatter:off
 		MultipleFailuresError multipleFailuresError = assertThrows(MultipleFailuresError.class, () ->
 			assertAll(asList(
-				() -> fail(),
-				() -> fail()
+				Assertions::fail,
+				Assertions::fail
 			))
 		);
 		// @formatter:on
@@ -137,8 +136,8 @@ void assertAllWithStreamOfExecutablesThatThrowAssertionErrors() {
 		// @formatter:off
 		MultipleFailuresError multipleFailuresError = assertThrows(MultipleFailuresError.class, () ->
 			assertAll(Stream.of(
-				() -> fail(),
-				() -> fail()
+				Assertions::fail,
+				Assertions::fail
 			))
 		);
 		// @formatter:on

jupiter-tests/src/test/java/org/junit/jupiter/api/AssertDoesNotThrowAssertionsTests.java

@@ -36,9 +36,7 @@ class AssertDoesNotThrowAssertionsTests {
 
 	@Test
 	void assertDoesNotThrowWithMethodReferenceForNonVoidReturnType() {
-		FutureTask<String> future = new FutureTask<>(() -> {
-			return "foo";
-		});
+		FutureTask<String> future = new FutureTask<>(() -> "foo");
 		future.run();
 
 		String result;

jupiter-tests/src/test/java/org/junit/jupiter/engine/extension/TestWatcherTests.java

@@ -31,6 +31,7 @@
 import java.util.stream.Stream;
 
 import org.jspecify.annotations.Nullable;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.DynamicTest;
@@ -305,7 +306,7 @@ Stream<DynamicTest> abortedTest() {
 		@TestFactory
 		@Disabled
 		Stream<DynamicTest> skippedTest() {
-			return Stream.of("A", "B").map(text -> dynamicTest(text, () -> fail()));
+			return Stream.of("A", "B").map(text -> dynamicTest(text, Assertions::fail));
 		}
 
 	}

platform-tests/src/test/java/org/junit/platform/console/ConsoleLauncherWrapperResult.java

@@ -38,7 +38,7 @@ class ConsoleLauncherWrapperResult implements TestExecutionSummary {
 		this.err = err;
 		this.code = result.getExitCode();
 		this.summary = (TestExecutionSummary) result.getValue() //
-				.filter(it -> it instanceof TestExecutionSummary) //
+				.filter(TestExecutionSummary.class::isInstance) //
 				.orElse(null);
 	}
 

platform-tests/src/test/java/org/junit/platform/launcher/tagexpression/ParserTests.java

@@ -76,7 +76,7 @@ private static Stream<Arguments> data() {
 
 	private TagExpression tagExpressionParsedFrom(String tagExpression) {
 		return parser.parse(tagExpression).tagExpressionOrThrow(
-			(error) -> new RuntimeException("[" + tagExpression + "] should be parsable"));
+			error -> new RuntimeException("[" + tagExpression + "] should be parsable"));
 	}
 
 }

platform-tests/src/test/java/org/junit/platform/launcher/tagexpression/TokenizerTests.java

@@ -79,11 +79,11 @@ void extractStartPositionOfRawString() {
 	}
 
 	private Stream<Integer> startIndicesExtractedFrom(String expression) {
-		return tokensExtractedFrom(expression).map(token -> token.startIndex());
+		return tokensExtractedFrom(expression).map(Token::startIndex);
 	}
 
 	private Stream<String> rawStringsExtractedFrom(String expression) {
-		return tokensExtractedFrom(expression).map(token -> token.rawString());
+		return tokensExtractedFrom(expression).map(Token::rawString);
 	}
 
 	private List<String> tokenStringsExtractedFrom(@Nullable String expression) {