Fix ignored test with duplicate key in dataprovider

src/Util/Test.php

@@ -879,7 +879,7 @@ private static function getDataFromDataProviderAnnotation(string $docComment, st
                     $data     = [];
 
                     foreach ($origData as $key => $value) {
-                        if (\is_int($key)) {
+                        if (\is_int($key) || \array_key_exists($key, $data)) {
                             $data[] = $value;
                         } else {
                             $data[$key] = $value;

tests/_files/DuplicateKeyDataProviderTest.php

@@ -0,0 +1,27 @@
+<?php
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+use PHPUnit\Framework\TestCase;
+
+class DuplicateKeyDataProviderTest extends TestCase
+{
+    public static function dataProvider()
+    {
+        yield 'foo' => ['foo'];
+
+        yield 'foo' => ['bar'];
+    }
+
+    /**
+     * @dataProvider dataProvider
+     */
+    public function test($arg): void
+    {
+    }
+}

tests/unit/Util/TestTest.php

@@ -562,6 +562,16 @@ public function testWithVariousIterableDataProviders(): void
         ], $dataSets);
     }
 
+    public function testWithVDuplicateKeyDataProviders(): void
+    {
+        $dataSets = Test::getProvidedData(\DuplicateKeyDataProviderTest::class, 'test');
+
+        $this->assertEquals([
+            'foo' => ['foo'],
+            ['bar'],
+        ], $dataSets);
+    }
+
     public function testTestWithEmptyAnnotation(): void
     {
         $result = Test::getDataFromTestWithAnnotation("/**\n * @anotherAnnotation\n */");