Fix getColumnName() with negative index

src/Cache/ArrayResult.php

@@ -88,11 +88,8 @@ public function columnCount(): int
 
     public function getColumnName(int $index): string
     {
-        if ($this->data === [] || $index > count($this->data[0])) {
-            throw InvalidColumnIndex::new($index);
-        }
-
-        return array_keys($this->data[0])[$index];
+        return array_keys($this->data[0] ?? [])[$index]
+            ?? throw InvalidColumnIndex::new($index);
     }
 
     public function free(): void

tests/Cache/ArrayResultTest.php

@@ -0,0 +1,104 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Tests\Cache;
+
+use Doctrine\DBAL\Cache\ArrayResult;
+use Doctrine\DBAL\Exception\InvalidColumnIndex;
+use PHPUnit\Framework\Attributes\TestWith;
+use PHPUnit\Framework\TestCase;
+
+use function array_values;
+
+class ArrayResultTest extends TestCase
+{
+    /** @var list<array<string, mixed>> */
+    private array $users = [
+        [
+            'username' => 'jwage',
+            'active' => true,
+        ],
+        [
+            'username' => 'romanb',
+            'active' => false,
+        ],
+    ];
+
+    public function testCloseCursor(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame(2, $result->rowCount());
+
+        $result->free();
+
+        self::assertSame(0, $result->rowCount());
+    }
+
+    public function testColumnCount(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame(2, $result->columnCount());
+    }
+
+    public function testColumnNames(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame('username', $result->getColumnName(0));
+        self::assertSame('active', $result->getColumnName(1));
+    }
+
+    #[TestWith([2])]
+    #[TestWith([-1])]
+    public function testInvalidColumnIndex(int $index): void
+    {
+        $result = $this->createTestArrayResult();
+        $this->expectException(InvalidColumnIndex::class);
+
+        $result->getColumnName($index);
+    }
+
+    public function testRowCount(): void
+    {
+        $statement = $this->createTestArrayResult();
+
+        self::assertSame(2, $statement->rowCount());
+    }
+
+    public function testFetchAssociative(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame($this->users[0], $result->fetchAssociative());
+    }
+
+    public function testFetchNumeric(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame(array_values($this->users[0]), $result->fetchNumeric());
+    }
+
+    public function testFetchOne(): void
+    {
+        $result = $this->createTestArrayResult();
+
+        self::assertSame('jwage', $result->fetchOne());
+        self::assertSame('romanb', $result->fetchOne());
+    }
+
+    public function testFetchAll(): void
+    {
+        $statement = $this->createTestArrayResult();
+
+        self::assertSame($this->users, $statement->fetchAllAssociative());
+    }
+
+    private function createTestArrayResult(): ArrayResult
+    {
+        return new ArrayResult($this->users);
+    }
+}

tests/Functional/ResultMetadataTest.php

@@ -7,6 +7,7 @@
 use Doctrine\DBAL\Exception\InvalidColumnIndex;
 use Doctrine\DBAL\Schema\Table;
 use Doctrine\DBAL\Tests\FunctionalTestCase;
+use PHPUnit\Framework\Attributes\TestWith;
 
 use function strtolower;
 
@@ -36,7 +37,9 @@ public function testColumnNameWithResults(): void
         self::assertEquals('alternate_name', strtolower($result->getColumnName(1)));
     }
 
-    public function testColumnNameWithInvalidIndex(): void
+    #[TestWith([2])]
+    #[TestWith([-1])]
+    public function testColumnNameWithInvalidIndex(int $index): void
     {
         $sql = 'SELECT test_int, test_int AS alternate_name FROM result_metadata_table';
 
@@ -47,7 +50,7 @@ public function testColumnNameWithInvalidIndex(): void
 
         $this->expectException(InvalidColumnIndex::class);
 
-        $result->getColumnName(2);
+        $result->getColumnName($index);
     }
 
     public function testColumnNameWithoutResults(): void