validate dataProvider return/parameter types

src/Rules/PHPUnit/DataProviderDeclarationRule.php

@@ -84,6 +84,11 @@ public function processNode(Node $node, Scope $scope): array
 
 		$annotations = $this->dataProviderHelper->getDataProviderAnnotations($methodPhpDoc);
 
+		$testMethodReflection = null;
+		if ($classReflection->hasMethod($node->name->toString())) {
+			$testMethodReflection = $classReflection->getMethod($node->name->toString(), $scope);
+		}
+
 		$errors = [];
 
 		foreach ($annotations as $annotation) {
@@ -93,7 +98,8 @@ public function processNode(Node $node, Scope $scope): array
 					$scope,
 					$annotation,
 					$this->checkFunctionNameCase,
-					$this->deprecationRulesInstalled
+					$this->deprecationRulesInstalled,
+					$testMethodReflection
 				)
 			);
 		}

src/Rules/PHPUnit/DataProviderHelper.php

@@ -5,10 +5,15 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\PhpDoc\ResolvedPhpDocBlock;
 use PHPStan\PhpDocParser\Ast\PhpDoc\PhpDocTagNode;
+use PHPStan\Reflection\ExtendedMethodReflection;
 use PHPStan\Reflection\MissingMethodFromReflectionException;
+use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Rules\RuleError;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Type\UnionType;
+use PHPStan\Type\VerbosityLevel;
 use function array_merge;
+use function count;
 use function preg_match;
 use function sprintf;
 
@@ -45,7 +50,8 @@ public function processDataProvider(
 		Scope $scope,
 		PhpDocTagNode $phpDocTag,
 		bool $checkFunctionNameCase,
-		bool $deprecationRulesInstalled
+		bool $deprecationRulesInstalled,
+		?ExtendedMethodReflection $testMethodReflection
 	): array
 	{
 		$dataProviderName = $this->getDataProviderName($phpDocTag);
@@ -95,6 +101,58 @@ public function processDataProvider(
 			))->build();
 		}
 
+		$dataProviderParameterAcceptor = ParametersAcceptorSelector::selectSingle($dataProviderMethodReflection->getVariants());
+		$providerReturnType = $dataProviderParameterAcceptor->getReturnType();
+		if ($testMethodReflection !== null && $providerReturnType->isIterable()->yes()) {
+			$collectionType = $providerReturnType->getIterableValueType();
+
+			if ($collectionType->isIterable()->yes()) {
+				$testParameterAcceptor = ParametersAcceptorSelector::selectSingle($testMethodReflection->getVariants());
+
+				$valueType = $collectionType->getIterableValueType();
+
+				if ($valueType instanceof UnionType) {
+					if (count($valueType->getTypes()) !== count($testParameterAcceptor->getParameters())) {
+						$errors[] = RuleErrorBuilder::message(sprintf(
+							'@dataProvider %s returns a different number of values the test method expects.',
+							$dataProviderName
+						))->build();
+
+						return $errors;
+					}
+
+					foreach ($valueType->getTypes() as $i => $innerType) {
+						if (!$testParameterAcceptor->getParameters()[$i]->getType()->accepts($innerType, $scope->isDeclareStrictTypes())->yes()) {
+							$errors[] = RuleErrorBuilder::message(sprintf(
+								'@dataProvider %s returns %s which is not compatible with the test method parameters.',
+								$dataProviderName,
+								$providerReturnType->describe(VerbosityLevel::precise())
+							))->build();
+
+							return $errors;
+						}
+					}
+				} else {
+					if (count($testParameterAcceptor->getParameters()) !== 1) {
+						$errors[] = RuleErrorBuilder::message(sprintf(
+							'@dataProvider %s returns a different number of values the test method expects.',
+							$dataProviderName
+						))->build();
+
+						return $errors;
+					}
+
+					if (!$testParameterAcceptor->getParameters()[0]->getType()->accepts($valueType, $scope->isDeclareStrictTypes())->yes()) {
+						$errors[] = RuleErrorBuilder::message(sprintf(
+							'@dataProvider %s returns %s which is not compatible with the test method parameters.',
+							$dataProviderName,
+							$providerReturnType->describe(VerbosityLevel::precise())
+						))->build();
+					}
+				}
+			}
+		}
+
 		return $errors;
 	}
 

tests/Rules/PHPUnit/DataProviderDeclarationRuleTest.php

@@ -41,6 +41,26 @@ public function testRule(): void
 				'@dataProvider provideNonExisting related method not found.',
 				66,
 			],
+			[
+				'@dataProvider provideMultiple returns a different number of values the test method expects.',
+				79,
+			],
+			[
+				'@dataProvider provideArray returns iterable<int, array<string>> which is not compatible with the test method parameters.',
+				101,
+			],
+			[
+				'@dataProvider provideIterator returns Iterator<mixed, array<int, string>> which is not compatible with the test method parameters.',
+				101,
+			],
+			[
+				'@dataProvider provideMultiple returns a different number of values the test method expects.',
+				101,
+			],
+			[
+				'@dataProvider provideMultiple returns Iterator<mixed, array{string, int}> which is not compatible with the test method parameters.',
+				116,
+			],
 		]);
 	}
 

tests/Rules/PHPUnit/data/data-provider-declaration.php

@@ -68,3 +68,79 @@ public function testIsNotBar(string $subject): void
 		self::assertNotSame('bar', $subject);
 	}
 }
+
+class FooBarTestCase extends \PHPUnit\Framework\TestCase
+{
+	/**
+	 * @dataProvider provideArray
+	 * @dataProvider provideIterator
+	 * @dataProvider provideMultiple
+	 */
+	public function testIsNotFooBar(string $subject): void
+	{
+		self::assertNotSame('foo', $subject);
+	}
+
+	/**
+	 * @dataProvider provideArray
+	 * @dataProvider provideIterator
+	 *
+	 * @param string $subject
+	 */
+	public function testIsNotFooBarPhpDoc($subject): void
+	{
+		self::assertNotSame('foo', $subject);
+	}
+
+
+	/**
+	 * @dataProvider provideArray
+	 * @dataProvider provideIterator
+	 * @dataProvider provideMultiple
+	 */
+	public function testIsFooBar(int $subject): void
+	{
+		self::assertNotSame(123, $subject);
+	}
+
+	/**
+	 * @dataProvider provideMultiple
+	 */
+	public function testMultipleParams(string $subject, int $i): void
+	{
+	}
+
+	/**
+	 * @dataProvider provideMultiple
+	 */
+	public function testBogusMultipleParams(float $subject, string $i): void
+	{
+	}
+
+
+	/**
+	 * @return list<array<string>>
+	 */
+	public static function provideArray(): iterable
+	{
+		return [
+			['bar'],
+		];
+	}
+
+	/**
+	 * @return \Iterator<list<string>>
+	 */
+	public static function provideIterator(): \Iterator
+	{
+		yield ['bar'];
+	}
+
+	/**
+	 * @return \Iterator<array{string, int}>
+	 */
+	public static function provideMultiple(): \Iterator
+	{
+		yield ['bar', 1];
+	}
+}