Issue: #3708 add ParameterizedTest#argumentCountValidation

This allows parameterized tests to fail
when there are more arguments provided than declared by the test method.
This is done in a backwards compatible way
by only enabling that validation when the new
`junit.jupiter.params.argumentCountValidation` is set to `strict`
or `ParameterizedTest#argumentCountValidation` is set to
`ArgumentCountValidationMode.STRICT`.

Author: jonas-jebing-at-ebay

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

@@ -0,0 +1,52 @@
+/*
+ * 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;
+
+import org.apiguardian.api.API;
+import org.junit.jupiter.params.provider.ArgumentsSource;
+
+/**
+ * Enumeration of argument count validation modes for {@link ParameterizedTest @ParameterizedTest}.
+ *
+ * <p>When an {@link ArgumentsSource} provides more arguments than declared by the test method,
+ * there might be a bug in the test method or the {@link ArgumentsSource}.
+ * By default, the additional arguments are ignored.
+ * {@link ArgumentCountValidationMode} allows you to control how additional arguments are handled.
+ *
+ * @since 5.12
+ * @see ParameterizedTest
+ */
+@API(status = API.Status.EXPERIMENTAL, since = "5.12")
+public enum ArgumentCountValidationMode {
+	/**
+	 * Use the default cleanup mode.
+	 *
+	 * <p>The default cleanup mode may be changed via the
+	 * {@value ParameterizedTestExtension#ARGUMENT_COUNT_VALIDATION_KEY} configuration parameter
+	 * (see the User Guide for details on configuration parameters).
+	 */
+	DEFAULT,
+
+	/**
+	 * Use the "none" argument count validation mode.
+	 *
+	 * <p>When there are more arguments provided than declared by the test method,
+	 * these additional arguments are ignored.
+	 */
+	NONE,
+
+	/**
+	 * Use the strict argument count validation mode.
+	 *
+	 * <p>When there are more arguments provided than declared by the test method, this raises an error.
+	 */
+	STRICT,
+}

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

@@ -22,6 +22,7 @@
 import org.apiguardian.api.API;
 import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.params.provider.ArgumentsSource;
 
 /**
  * {@code @ParameterizedTest} is used to signal that the annotated method is a
@@ -291,4 +292,21 @@
 	@API(status = STABLE, since = "5.10")
 	boolean autoCloseArguments() default true;
 
+	/**
+	 * Configure how the number of arguments provided by an {@link ArgumentsSource} are validated.
+	 *
+	 * <p>Defaults to {@link ArgumentCountValidationMode#DEFAULT}.
+	 *
+	 * <p>When an {@link ArgumentsSource} provides more arguments than declared by the test method,
+	 * there might be a bug in the test method or the {@link ArgumentsSource}.
+	 * By default, the additional arguments are ignored.
+	 * {@code argumentCountValidation} allows you to control how additional arguments are handled.
+	 * This can also be controlled via the {@value ParameterizedTestExtension#ARGUMENT_COUNT_VALIDATION_KEY}
+	 * configuration parameter (see the User Guide for details on configuration parameters).
+	 *
+	 * @since 5.12
+	 * @see ArgumentCountValidationMode
+	 */
+	@API(status = EXPERIMENTAL, since = "5.12")
+	ArgumentCountValidationMode argumentCountValidation() default ArgumentCountValidationMode.DEFAULT;
 }

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

@@ -15,9 +15,13 @@
 import static org.junit.platform.commons.support.AnnotationSupport.isAnnotated;
 
 import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.NoSuchElementException;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Stream;
 
+import org.junit.jupiter.api.extension.ExtensionConfigurationException;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.api.extension.ExtensionContext.Namespace;
 import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
@@ -26,6 +30,8 @@
 import org.junit.jupiter.params.provider.ArgumentsProvider;
 import org.junit.jupiter.params.provider.ArgumentsSource;
 import org.junit.jupiter.params.support.AnnotationConsumerInitializer;
+import org.junit.platform.commons.logging.Logger;
+import org.junit.platform.commons.logging.LoggerFactory;
 import org.junit.platform.commons.util.ExceptionUtils;
 import org.junit.platform.commons.util.Preconditions;
 
@@ -34,10 +40,13 @@
  */
 class ParameterizedTestExtension implements TestTemplateInvocationContextProvider {
 
+	private static final Logger logger = LoggerFactory.getLogger(ParameterizedTestExtension.class);
+
 	private static final String METHOD_CONTEXT_KEY = "context";
 	static final String ARGUMENT_MAX_LENGTH_KEY = "junit.jupiter.params.displayname.argument.maxlength";
 	static final String DEFAULT_DISPLAY_NAME = "{default_display_name}";
 	static final String DISPLAY_NAME_PATTERN_KEY = "junit.jupiter.params.displayname.default";
+	static final String ARGUMENT_COUNT_VALIDATION_KEY = "junit.jupiter.params.argumentCountValidation";
 
 	@Override
 	public boolean supportsTestTemplate(ExtensionContext context) {
@@ -86,6 +95,7 @@ public Stream<TestTemplateInvocationContext> provideTestTemplateInvocationContex
 				.map(provider -> AnnotationConsumerInitializer.initialize(templateMethod, provider))
 				.flatMap(provider -> arguments(provider, extensionContext))
 				.map(arguments -> {
+					validateArgumentCount(extensionContext, arguments);
 					invocationCount.incrementAndGet();
 					return createInvocationContext(formatter, methodContext, arguments, invocationCount.intValue());
 				})
@@ -99,6 +109,55 @@ private ExtensionContext.Store getStore(ExtensionContext context) {
 		return context.getStore(Namespace.create(ParameterizedTestExtension.class, context.getRequiredTestMethod()));
 	}
 
+	private void validateArgumentCount(ExtensionContext extensionContext, Arguments arguments) {
+		ArgumentCountValidationMode argumentCountValidationMode = getArgumentCountValidationMode(extensionContext);
+		switch (argumentCountValidationMode) {
+			case DEFAULT:
+			case NONE:
+				return;
+			case STRICT:
+				int testParamCount = extensionContext.getRequiredTestMethod().getParameterCount();
+				int argumentsCount = arguments.get().length;
+				Preconditions.condition(testParamCount == argumentsCount, () -> String.format(
+					"Configuration error: the @ParameterizedTest has %s argument(s) but there were %s argument(s) provided./nNote: the provided arguments are %s",
+					testParamCount, argumentsCount, Arrays.toString(arguments.get())));
+				break;
+			default:
+				throw new ExtensionConfigurationException(
+					"Unsupported argument count validation mode: " + argumentCountValidationMode);
+		}
+	}
+
+	private ArgumentCountValidationMode getArgumentCountValidationMode(ExtensionContext extensionContext) {
+		ParameterizedTest parameterizedTest = findAnnotation(//
+			extensionContext.getRequiredTestMethod(), ParameterizedTest.class//
+		).orElseThrow(NoSuchElementException::new);
+		if (parameterizedTest.argumentCountValidation() != ArgumentCountValidationMode.DEFAULT) {
+			return parameterizedTest.argumentCountValidation();
+		}
+		else {
+			return getArgumentCountValidationModeConfiguration(extensionContext);
+		}
+	}
+
+	private ArgumentCountValidationMode getArgumentCountValidationModeConfiguration(ExtensionContext extensionContext) {
+		String key = ARGUMENT_COUNT_VALIDATION_KEY;
+		ArgumentCountValidationMode fallback = ArgumentCountValidationMode.DEFAULT;
+		Optional<String> optionalValue = extensionContext.getConfigurationParameter(key);
+		if (optionalValue.isPresent()) {
+			String value = optionalValue.get();
+			return Arrays.stream(ArgumentCountValidationMode.values()).filter(
+				mode -> mode.name().equalsIgnoreCase(value)).findFirst().orElseGet(() -> {
+					logger.warn(() -> String.format(
+						"Ignored invalid configuration '%s' set via the '%s' configuration parameter.", value, key));
+					return fallback;
+				});
+		}
+		else {
+			return fallback;
+		}
+	}
+
 	private TestTemplateInvocationContext createInvocationContext(ParameterizedTestNameFormatter formatter,
 			ParameterizedTestMethodContext methodContext, Arguments arguments, int invocationIndex) {
 

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

@@ -115,6 +115,7 @@
 import org.junit.platform.testkit.engine.EngineExecutionResults;
 import org.junit.platform.testkit.engine.EngineTestKit;
 import org.junit.platform.testkit.engine.Event;
+import org.junit.platform.testkit.engine.EventConditions;
 import org.opentest4j.TestAbortedException;
 
 /**
@@ -1093,6 +1094,42 @@ private EngineExecutionResults execute(String methodName, Class<?>... methodPara
 
 	}
 
+	@Nested
+	class UnusedArgumentsWithStrictArgumentsCountIntegrationTests {
+		@Test
+		void failsWithArgumentsSourceProvidingUnusedArguments() {
+			var results = execute(UnusedArgumentsTestCase.class, "testWithTwoUnusedStringArgumentsProvider",
+				String.class);
+			results.allEvents().assertThatEvents() //
+					.haveExactly(1, event(EventConditions.finishedWithFailure(message(
+						"Configuration error: the @ParameterizedTest has 1 argument(s) but there were 2 argument(s) provided./nNote: the provided arguments are [foo, unused1]"))));
+		}
+
+		@Test
+		void failsWithMethodSourceProvidingUnusedArguments() {
+			var results = execute(UnusedArgumentsTestCase.class, "testWithMethodSourceProvidingUnusedArguments",
+				String.class);
+			results.allEvents().assertThatEvents() //
+					.haveExactly(1, event(EventConditions.finishedWithFailure(message(
+						"Configuration error: the @ParameterizedTest has 1 argument(s) but there were 2 argument(s) provided./nNote: the provided arguments are [foo, unused1]"))));
+		}
+
+		@Test
+		void executesWithMethodSourceProvidingUnusedArguments() {
+			var results = execute(RepeatableSourcesTestCase.class, "testWithRepeatableCsvSource", String.class);
+			results.allEvents().assertThatEvents() //
+					.haveExactly(1, event(test(), displayName("[1] argument=a"), finishedWithFailure(message("a")))) //
+					.haveExactly(1, event(test(), displayName("[2] argument=b"), finishedWithFailure(message("b"))));
+		}
+
+		private EngineExecutionResults execute(Class<?> javaClass, String methodName,
+				Class<?>... methodParameterTypes) {
+			return EngineTestKit.engine(new JupiterTestEngine()).selectors(
+				selectMethod(javaClass, methodName, methodParameterTypes)).configurationParameter(
+					ParameterizedTestExtension.ARGUMENT_COUNT_VALIDATION_KEY, "strict").execute();
+		}
+	}
+
 	@Nested
 	class RepeatableSourcesIntegrationTests {