Make parameterized ArgumentSource annotations repeatable

This commit makes every `@..Source` annotations that makes use of 
`AnnotationBasedArgumentsProvider` repeatable by adapting to accept 
multiple annotations while aggregating the result of each annotation 
argument.

This change does not affect annotations related to null and/or empty 
sources: `@NullSource`, `@EmptySource` and `@NullAndEmptySource` since 
they have predefined/hardcoded arguments relevant to null and empty 
values.

Resolves #3736.

documentation/src/docs/asciidoc/release-notes/release-notes-5.11.0-M2.adoc

@@ -58,8 +58,9 @@ repository on GitHub.
 [[release-notes-5.11.0-M2-junit-jupiter-new-features-and-improvements]]
 ==== New Features and Improvements
 
-* ❓
-
+* Support `@..Source` annotations as repeatable for parameterized tests. See the
+<<../user-guide/index.adoc#writing-tests-parameterized-repeatable-sources, User Guide>>
+for more details.
 
 [[release-notes-5.11.0-M2-junit-vintage]]
 === JUnit Vintage

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

@@ -1963,6 +1963,34 @@ If you wish to implement a custom `ArgumentsProvider` that also consumes an anno
 (like built-in providers such as `{ValueArgumentsProvider}` or `{CsvArgumentsProvider}`),
 you have the possibility to extend the `{AnnotationBasedArgumentsProvider}` class.
 
+[[writing-tests-parameterized-repeatable-sources]]
+===== Multiple sources using repeatable annotations
+Repeatable annotations provide a convenient way to specify multiple sources from
+different providers.
+
+[source,java,indent=0]
+----
+include::{testDir}/example/ParameterizedTestDemo.java[tags=repeatable_annotations]
+----
+
+Following the above parameterized test, a test case will run for each argument:
+
+----
+[1] foo
+[2] bar
+----
+
+The following annotations are repeatable:
+
+* `@ValueSource`
+* `@EnumSource`
+* `@MethodSource`
+* `@FieldSource`
+* `@CsvSource`
+* `@CsvFileSource`
+* `@ArgumentsSource`
+
+
 [[writing-tests-parameterized-tests-argument-conversion]]
 ==== Argument Conversion
 

documentation/src/test/java/example/ParameterizedTestDemo.java

@@ -542,4 +542,22 @@ static Stream<Arguments> namedArguments() {
 	}
 	// end::named_arguments[]
 	// @formatter:on
+
+	// tag::repeatable_annotations[]
+	@DisplayName("A parameterized test that makes use of repeatable annotations")
+	@ParameterizedTest
+	@MethodSource("someProvider")
+	@MethodSource("otherProvider")
+	void testWithRepeatedAnnotation(String argument) {
+		assertNotNull(argument);
+	}
+
+	static Stream<String> someProvider() {
+		return Stream.of("foo");
+	}
+
+	static Stream<String> otherProvider() {
+		return Stream.of("bar");
+	}
+	// end::repeatable_annotations[]
 }

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/AnnotationBasedArgumentsProvider.java

@@ -13,6 +13,8 @@
 import static org.apiguardian.api.API.Status.EXPERIMENTAL;
 
 import java.lang.annotation.Annotation;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.stream.Stream;
 
 import org.apiguardian.api.API;
@@ -39,17 +41,17 @@ public abstract class AnnotationBasedArgumentsProvider<A extends Annotation>
 	public AnnotationBasedArgumentsProvider() {
 	}
 
-	private A annotation;
+	private final List<A> annotations = new ArrayList<>();
 
 	@Override
 	public final void accept(A annotation) {
 		Preconditions.notNull(annotation, "annotation must not be null");
-		this.annotation = annotation;
+		annotations.add(annotation);
 	}
 
 	@Override
 	public final Stream<? extends Arguments> provideArguments(ExtensionContext context) {
-		return provideArguments(context, this.annotation);
+		return annotations.stream().flatMap(annotation -> provideArguments(context, annotation));
 	}
 
 	/**

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/CsvFileSource.java

@@ -14,16 +14,17 @@
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
 import org.apiguardian.api.API;
 
 /**
- * {@code @CsvFileSource} is an {@link ArgumentsSource} which is used to load
- * comma-separated value (CSV) files from one or more classpath {@link #resources}
- * or {@link #files}.
+ * {@code @CsvFileSource} is a {@linkplain Repeatable repeatable}
+ * {@link ArgumentsSource} which is used to load comma-separated value (CSV)
+ * files from one or more classpath {@link #resources} or {@link #files}.
  *
  * <p>The CSV records parsed from these resources and files will be provided as
  * arguments to the annotated {@code @ParameterizedTest} method. Note that the
@@ -63,6 +64,7 @@
 @Target({ ElementType.ANNOTATION_TYPE, ElementType.METHOD })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(CsvFileSources.class)
 @API(status = STABLE, since = "5.7")
 @ArgumentsSource(CsvFileArgumentsProvider.class)
 @SuppressWarnings("exports")

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/CsvFileSources.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2015-2024 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.jupiter.params.provider;
+
+import static org.apiguardian.api.API.Status.STABLE;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.apiguardian.api.API;
+
+/**
+ * {@code @CsvFileSources} is a simple container for one or more
+ * {@link CsvFileSource} annotations.
+ *
+ * <p>Note, however, that use of the {@code @CsvFileSources} container is completely
+ * optional since {@code @CsvFileSource} is a {@linkplain java.lang.annotation.Repeatable
+ * repeatable} annotation.
+ *
+ * @since 5.11
+ * @see CsvFileSource
+ * @see java.lang.annotation.Repeatable
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@API(status = STABLE, since = "5.11")
+public @interface CsvFileSources {
+
+	/**
+	 * An array of one or more {@link CsvFileSource @CsvFileSource}
+	 * annotations.
+	 */
+	CsvFileSource[] value();
+}

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/CsvSource.java

@@ -14,16 +14,18 @@
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
 import org.apiguardian.api.API;
 
 /**
- * {@code @CsvSource} is an {@link ArgumentsSource} which reads comma-separated
- * values (CSV) from one or more CSV records supplied via the {@link #value}
- * attribute or {@link #textBlock} attribute.
+ * {@code @CsvSource} is a {@linkplain Repeatable repeatable}
+ * {@link ArgumentsSource} which reads comma-separated values (CSV) from one
+ * or more CSV records supplied via the {@link #value} attribute or
+ * {@link #textBlock} attribute.
  *
  * <p>The supplied values will be provided as arguments to the annotated
  * {@code @ParameterizedTest} method.
@@ -64,6 +66,7 @@
  */
 @Target({ ElementType.ANNOTATION_TYPE, ElementType.METHOD })
 @Retention(RetentionPolicy.RUNTIME)
+@Repeatable(CsvSources.class)
 @Documented
 @API(status = STABLE, since = "5.7")
 @ArgumentsSource(CsvArgumentsProvider.class)

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/CsvSources.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2015-2024 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.jupiter.params.provider;
+
+import static org.apiguardian.api.API.Status.STABLE;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.apiguardian.api.API;
+
+/**
+ * {@code @CsvSources} is a simple container for one or more
+ * {@link CsvSource} annotations.
+ *
+ * <p>Note, however, that use of the {@code @CsvSources} container is completely
+ * optional since {@code @CsvSource} is a {@linkplain java.lang.annotation.Repeatable
+ * repeatable} annotation.
+ *
+ * @since 5.11
+ * @see CsvSource
+ * @see java.lang.annotation.Repeatable
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@API(status = STABLE, since = "5.11")
+public @interface CsvSources {
+
+	/**
+	 * An array of one or more {@link CsvSource @CsvSource}
+	 * annotations.
+	 */
+	CsvSource[] value();
+}

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/EnumSource.java

@@ -16,6 +16,7 @@
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -29,8 +30,8 @@
 import org.junit.platform.commons.util.Preconditions;
 
 /**
- * {@code @EnumSource} is an {@link ArgumentsSource} for constants of
- * an {@link Enum}.
+ * {@code @EnumSource} is a {@linkplain Repeatable repeatable}
+ * {@link ArgumentsSource} for constants of an {@link Enum}.
  *
  * <p>The enum constants will be provided as arguments to the annotated
  * {@code @ParameterizedTest} method.
@@ -49,6 +50,7 @@
 @Target({ ElementType.ANNOTATION_TYPE, ElementType.METHOD })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(EnumSources.class)
 @API(status = STABLE, since = "5.7")
 @ArgumentsSource(EnumArgumentsProvider.class)
 @SuppressWarnings("exports")

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/EnumSources.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2015-2024 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.jupiter.params.provider;
+
+import static org.apiguardian.api.API.Status.STABLE;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.apiguardian.api.API;
+
+/**
+ * {@code @EnumSources} is a simple container for one or more
+ * {@link EnumSource} annotations.
+ *
+ * <p>Note, however, that use of the {@code @EnumSources} container is completely
+ * optional since {@code @EnumSource} is a {@linkplain java.lang.annotation.Repeatable
+ * repeatable} annotation.
+ *
+ * @since 5.11
+ * @see EnumSource
+ * @see java.lang.annotation.Repeatable
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@API(status = STABLE, since = "5.11")
+public @interface EnumSources {
+
+	/**
+	 * An array of one or more {@link EnumSource @EnumSource}
+	 * annotations.
+	 */
+	EnumSource[] value();
+}

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/FieldSource.java

@@ -14,6 +14,7 @@
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -22,10 +23,11 @@
 import org.junit.jupiter.params.ParameterizedTest;
 
 /**
- * {@code @FieldSource} is an {@link ArgumentsSource} which provides access to
- * values of {@linkplain #value() fields} of the class in which this annotation
- * is declared or from static fields in external classes referenced by
- * <em>fully qualified field name</em>.
+ * {@code @FieldSource} is a {@linkplain Repeatable repeatable}
+ * {@link ArgumentsSource} which provides access to values of
+ * {@linkplain #value() fields} of the class in which this annotation is declared
+ * or from static fields in external classes referenced by <em>fully qualified
+ * field name</em>.
  *
  * <p>Each field must be able to supply a <em>stream</em> of <em>arguments</em>,
  * and each set of "arguments" within the "stream" will be provided as the physical
@@ -112,6 +114,7 @@
 @Target({ ElementType.ANNOTATION_TYPE, ElementType.METHOD })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(FieldSources.class)
 @API(status = EXPERIMENTAL, since = "5.11")
 @ArgumentsSource(FieldArgumentsProvider.class)
 @SuppressWarnings("exports")