Support CharSequence argument for Fallback String-to-Object Conversion

Prior to this commit, the Fallback String-to-Object Conversion support
for parameterized tests supported factory constructors and methods that
accepted a single String argument.

This commit relaxes that restriction to support factory constructors
and methods that accept either a single String argument or a single
CharSequence argument, since the original source String can always be
supplied to an Executable that accepts a CharSequence. For backward
compatibility, the search algorithm gives precedence to factories that
accept String arguments, only falling back to factories that accept
CharSequence arguments if necessary.

Note that this change is available to third parties via
ConversionSupport in junit-platform-commons, which junit-jupiter-params
utilizes.

Closes #4815

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/release-notes-6.0.0-RC1.adoc

@@ -27,6 +27,10 @@ repository on GitHub.
 ==== New Features and Improvements
 
 * Prune stack traces up to test or lifecycle method
+* Convention-based conversion in `ConversionSupport` now supports factory methods and
+  factory constructors that accept a single `CharSequence` argument in addition to the
+  existing support for factories that accept a single `String` argument.
+
 
 [[release-notes-6.0.0-RC1-junit-jupiter]]
 === JUnit Jupiter
@@ -52,6 +56,10 @@ repository on GitHub.
   In addition, special characters are escaped within quoted text. Please refer to the
   <<../user-guide/index.adoc#writing-tests-parameterized-tests-display-names-quoted-text,
   User Guide>> for details.
+* <<../user-guide/index.adoc#writing-tests-parameterized-tests-argument-conversion-implicit-fallback,
+  Fallback String-to-Object Conversion>> for parameterized tests now supports factory
+  methods and factory constructors that accept a single `CharSequence` argument in
+  addition to the existing support for factories that accept a single `String` argument.
 
 
 [[release-notes-6.0.0-RC1-junit-vintage]]

documentation/src/docs/asciidoc/user-guide/writing-tests.adoc

@@ -2519,11 +2519,12 @@ table, JUnit Jupiter also provides a fallback mechanism for automatic conversion
 method_ or a _factory constructor_ as defined below.
 
 - __factory method__: a non-private, `static` method declared in the target type that
-  accepts a single `String` argument and returns an instance of the target type. The name
-  of the method can be arbitrary and need not follow any particular convention.
+  accepts either a single `String` argument or a single `CharSequence` argument and
+  returns an instance of the target type. The name of the method can be arbitrary and need
+  not follow any particular convention.
 - __factory constructor__: a non-private constructor in the target type that accepts a
-  single `String` argument. Note that the target type must be declared as either a
-  top-level class or as a `static` nested class.
+  either a single `String` argument or a single `CharSequence` argument. Note that the
+  target type must be declared as either a top-level class or as a `static` nested class.
 
 NOTE: If multiple _factory methods_ are discovered, they will be ignored. If a _factory
 method_ and a _factory constructor_ are discovered, the factory method will be used

junit-platform-commons/src/main/java/org/junit/platform/commons/support/conversion/ConversionSupport.java

@@ -75,15 +75,20 @@ private ConversionSupport() {
 	 *
 	 * <ol>
 	 * <li>Search for a single, non-private static factory method in the target
-	 * type that converts from a String to the target type. Use the factory method
-	 * if present.</li>
+	 * type that converts from a {@link String} to the target type. Use the
+	 * factory method if present.</li>
 	 * <li>Search for a single, non-private constructor in the target type that
-	 * accepts a String. Use the constructor if present.</li>
+	 * accepts a {@link String}. Use the constructor if present.</li>
+	 * <li>Search for a single, non-private static factory method in the target
+	 * type that converts from a {@link CharSequence} to the target type. Use the
+	 * factory method if present.</li>
+	 * <li>Search for a single, non-private constructor in the target type that
+	 * accepts a {@link CharSequence}. Use the constructor if present.</li>
 	 * </ol>
 	 *
-	 * <p>If multiple suitable factory methods are discovered they will be ignored.
-	 * If neither a single factory method nor a single constructor is found, the
-	 * convention-based conversion strategy will not apply.
+	 * <p>If multiple suitable factory methods or constructors are discovered they
+	 * will be ignored. If neither a single factory method nor a single constructor
+	 * is found, the convention-based conversion strategy will not apply.
 	 *
 	 * @param source the source {@code String} to convert; may be {@code null}
 	 * but only if the target type is a reference type

junit-platform-commons/src/main/java/org/junit/platform/commons/support/conversion/FallbackStringToObjectConverter.java

@@ -38,16 +38,21 @@
  * <h2>Search Algorithm</h2>
  *
  * <ol>
- * <li>Search for a single, non-private static factory method in the target
- * type that converts from a String to the target type. Use the factory method
+ * <li>Search for a single, non-private static factory method in the target type
+ * that converts from a {@link String} to the target type. Use the factory method
  * if present.</li>
- * <li>Search for a single, non-private constructor in the target type that
- * accepts a String. Use the constructor if present.</li>
+ * <li>Search for a single, non-private constructor in the target type that accepts
+ * a {@link String}. Use the constructor if present.</li>
+ * <li>Search for a single, non-private static factory method in the target type
+ * that converts from a {@link CharSequence} to the target type. Use the factory
+ * method if present.</li>
+ * <li>Search for a single, non-private constructor in the target type that accepts
+ * a {@link CharSequence}. Use the constructor if present.</li>
  * </ol>
  *
- * <p>If multiple suitable factory methods are discovered they will be ignored.
- * If neither a single factory method nor a single constructor is found, this
- * converter acts as a no-op.
+ * <p>If multiple suitable factory methods or constructors are discovered they
+ * will be ignored. If neither a single factory method nor a single constructor
+ * is found, this converter acts as a no-op.
  *
  * @since 1.11
  * @see ConversionSupport
@@ -86,28 +91,47 @@ public boolean canConvertTo(Class<?> targetType) {
 
 	private static Function<String, @Nullable Object> findFactoryExecutable(Class<?> targetType) {
 		return factoryExecutableCache.computeIfAbsent(targetType, type -> {
-			Method factoryMethod = findFactoryMethod(type);
-			if (factoryMethod != null) {
-				return source -> invokeMethod(factoryMethod, null, source);
+			// First, search for exact String argument matches.
+			Function<String, @Nullable Object> factory = findFactoryExecutable(type, String.class);
+			if (factory != null) {
+				return factory;
 			}
-			Constructor<?> constructor = findFactoryConstructor(type);
-			if (constructor != null) {
-				return source -> newInstance(constructor, source);
+			// Second, fall back to CharSequence argument matches.
+			factory = findFactoryExecutable(type, CharSequence.class);
+			if (factory != null) {
+				return factory;
 			}
+			// Else, nothing found.
 			return NULL_EXECUTABLE;
 		});
 	}
 
-	private static @Nullable Method findFactoryMethod(Class<?> targetType) {
-		List<Method> factoryMethods = findMethods(targetType, new IsFactoryMethod(targetType), BOTTOM_UP);
+	private static @Nullable Function<String, @Nullable Object> findFactoryExecutable(Class<?> targetType,
+			Class<?> parameterType) {
+
+		Method factoryMethod = findFactoryMethod(targetType, parameterType);
+		if (factoryMethod != null) {
+			return source -> invokeMethod(factoryMethod, null, source);
+		}
+		Constructor<?> constructor = findFactoryConstructor(targetType, parameterType);
+		if (constructor != null) {
+			return source -> newInstance(constructor, source);
+		}
+		return null;
+	}
+
+	private static @Nullable Method findFactoryMethod(Class<?> targetType, Class<?> parameterType) {
+		List<Method> factoryMethods = findMethods(targetType, new IsFactoryMethod(targetType, parameterType),
+			BOTTOM_UP);
 		if (factoryMethods.size() == 1) {
 			return factoryMethods.get(0);
 		}
 		return null;
 	}
 
-	private static @Nullable Constructor<?> findFactoryConstructor(Class<?> targetType) {
-		List<Constructor<?>> constructors = findConstructors(targetType, new IsFactoryConstructor(targetType));
+	private static @Nullable Constructor<?> findFactoryConstructor(Class<?> targetType, Class<?> parameterType) {
+		List<Constructor<?>> constructors = findConstructors(targetType,
+			new IsFactoryConstructor(targetType, parameterType));
 		if (constructors.size() == 1) {
 			return constructors.get(0);
 		}
@@ -117,15 +141,9 @@ public boolean canConvertTo(Class<?> targetType) {
 	/**
 	 * {@link Predicate} that determines if the {@link Method} supplied to
 	 * {@link #test(Method)} is a non-private static factory method for the
-	 * supplied {@link #targetType}.
+	 * supplied {@link #targetType} and {@link #parameterType}.
 	 */
-	static class IsFactoryMethod implements Predicate<Method> {
-
-		private final Class<?> targetType;
-
-		IsFactoryMethod(Class<?> targetType) {
-			this.targetType = targetType;
-		}
+	record IsFactoryMethod(Class<?> targetType, Class<?> parameterType) implements Predicate<Method> {
 
 		@Override
 		public boolean test(Method method) {
@@ -136,39 +154,35 @@ public boolean test(Method method) {
 			if (isNotStatic(method)) {
 				return false;
 			}
-			return isNotPrivateAndAcceptsSingleStringArgument(method);
+			return isFactoryCandidate(method, this.parameterType);
 		}
-
 	}
 
 	/**
 	 * {@link Predicate} that determines if the {@link Constructor} supplied to
 	 * {@link #test(Constructor)} is a non-private factory constructor for the
-	 * supplied {@link #targetType}.
+	 * supplied {@link #targetType} and {@link #parameterType}.
 	 */
-	static class IsFactoryConstructor implements Predicate<Constructor<?>> {
-
-		private final Class<?> targetType;
-
-		IsFactoryConstructor(Class<?> targetType) {
-			this.targetType = targetType;
-		}
+	record IsFactoryConstructor(Class<?> targetType, Class<?> parameterType) implements Predicate<Constructor<?>> {
 
 		@Override
 		public boolean test(Constructor<?> constructor) {
 			// Please do not collapse the following into a single statement.
 			if (!constructor.getDeclaringClass().equals(this.targetType)) {
 				return false;
 			}
-			return isNotPrivateAndAcceptsSingleStringArgument(constructor);
+			return isFactoryCandidate(constructor, this.parameterType);
 		}
-
 	}
 
-	private static boolean isNotPrivateAndAcceptsSingleStringArgument(Executable executable) {
+	/**
+	 * Determine if the supplied {@link Executable} is not private and accepts a
+	 * single argument of the supplied parameter type.
+	 */
+	private static boolean isFactoryCandidate(Executable executable, Class<?> parameterType) {
 		return isNotPrivate(executable) //
 				&& (executable.getParameterCount() == 1) //
-				&& (executable.getParameterTypes()[0] == String.class);
+				&& (executable.getParameterTypes()[0] == parameterType);
 	}
 
 }

jupiter-tests/src/test/java/org/junit/jupiter/params/ParameterizedTestIntegrationTests.java

@@ -311,6 +311,17 @@ void executesWithImplicitGenericConverter() {
 					event(test(), displayName("[2] book = book 2"), finishedWithFailure(message("book 2"))));
 	}
 
+	/**
+	 * @since 6.0
+	 */
+	@Test
+	void executesWithImplicitGenericConverterWithCharSequenceConstructor() {
+		var results = execute("testWithImplicitGenericConverterWithCharSequenceConstructor", Record.class);
+		results.testEvents().assertThatEvents() //
+				.haveExactly(1, event(displayName("\"record 1\""), finishedWithFailure(message("record 1")))) //
+				.haveExactly(1, event(displayName("\"record 2\""), finishedWithFailure(message("record 2"))));
+	}
+
 	@Test
 	void legacyReportingNames() {
 		var results = execute("testWithCustomName", String.class, int.class);
@@ -1460,6 +1471,12 @@ void testWithImplicitGenericConverter(Book book) {
 			fail(book.title);
 		}
 
+		@ParameterizedTest(name = "{0}")
+		@ValueSource(strings = { "record 1", "record 2" })
+		void testWithImplicitGenericConverterWithCharSequenceConstructor(Record record) {
+			fail(record.title.toString());
+		}
+
 		@ParameterizedTest(quoteTextArguments = false)
 		@ValueSource(strings = { "O", "XXX" })
 		void testWithExplicitConverter(@ConvertWith(StringLengthConverter.class) int length) {
@@ -2673,6 +2690,9 @@ static Book factory(String title) {
 		}
 	}
 
+	record Record(CharSequence title) {
+	}
+
 	static class FailureInBeforeEachTestCase {
 
 		@BeforeEach