Ensure return value of data provider method is iterable

Author: sebastianbergmann

src/Metadata/Api/DataProvider.php

@@ -15,6 +15,7 @@
 use function get_debug_type;
 use function is_array;
 use function is_int;
+use function is_iterable;
 use function is_string;
 use function method_exists;
 use function sprintf;
@@ -134,6 +135,16 @@ private function dataProvidedByMethods(ReflectionMethod $testMethod, MetadataCol
 
                 /** @phpstan-ignore staticMethod.dynamicName */
                 $data = $className::$methodName();
+
+                if (!is_iterable($data)) {
+                    throw new InvalidDataProviderException(
+                        sprintf(
+                            'Data Provider method %s::%s() does not return an iterable',
+                            $_dataProvider->className(),
+                            $_dataProvider->methodName(),
+                        ),
+                    );
+                }
             } catch (Throwable $e) {
                 Event\Facade::emitter()->dataProviderMethodFinished(
                     $testMethodValueObject,

tests/end-to-end/event/_files/DataProviderNotIterableTest.php

@@ -0,0 +1,27 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\Event;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+final class DataProviderNotIterableTest extends TestCase
+{
+    public static function provider(): string
+    {
+        return 'string';
+    }
+
+    #[DataProvider('provider')]
+    public function testSomething(bool $value): void
+    {
+        $this->assertTrue($value);
+    }
+}

tests/end-to-end/event/data-provider-does-not-return-iterable.phpt

@@ -0,0 +1,30 @@
+--TEST--
+The right events are emitted in the right order for a test that uses a data provider that does not return an iterable
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--no-configuration';
+$_SERVER['argv'][] = '--debug';
+$_SERVER['argv'][] = __DIR__ . '/_files/DataProviderNotIterableTest.php';
+
+require __DIR__ . '/../../bootstrap.php';
+
+(new PHPUnit\TextUI\Application)->run($_SERVER['argv']);
+--EXPECTF--
+PHPUnit Started (PHPUnit %s using %s)
+Test Runner Configured
+Event Facade Sealed
+Data Provider Method Called (PHPUnit\TestFixture\Event\DataProviderNotIterableTest::provider for test method PHPUnit\TestFixture\Event\DataProviderNotIterableTest::testSomething)
+Data Provider Method Finished for PHPUnit\TestFixture\Event\DataProviderNotIterableTest::testSomething:
+- PHPUnit\TestFixture\Event\DataProviderNotIterableTest::provider
+Test Triggered PHPUnit Error (PHPUnit\TestFixture\Event\DataProviderNotIterableTest::testSomething)
+The data provider PHPUnit\TestFixture\Event\DataProviderNotIterableTest::provider specified for PHPUnit\TestFixture\Event\DataProviderNotIterableTest::testSomething is invalid
+Data Provider method PHPUnit\TestFixture\Event\DataProviderNotIterableTest::provider() does not return an iterable
+Test Runner Triggered Warning (No tests found in class "PHPUnit\TestFixture\Event\DataProviderNotIterableTest".)
+Test Suite Loaded (0 tests)
+Test Runner Started
+Test Suite Sorted
+Test Runner Execution Started (0 tests)
+Test Runner Execution Finished
+Test Runner Finished
+PHPUnit Finished (Shell Exit Code: 2)