Fix script evaluation

src/Locator/Locator.php

@@ -407,7 +407,8 @@ public function nth(int $index): self
 
     public function evaluate(string $expression, mixed $arg = null): mixed
     {
-        $response = $this->sendCommand('locator.evaluate', ['expression' => $expression, 'arg' => $arg]);
+        $normalized = self::normalizeForLocator($expression);
+        $response = $this->sendCommand('locator.evaluate', ['expression' => $normalized, 'arg' => $arg]);
 
         return $response['value'] ?? null;
     }
@@ -447,6 +448,32 @@ private function sendCommand(string $action, array $params = []): array
         return $response;
     }
 
+    private static function normalizeForLocator(string $expression): string
+    {
+        $trimmed = ltrim($expression);
+
+        if (self::isFunctionLike($trimmed)) {
+            return $expression;
+        }
+
+        if (self::startsWithReturn($trimmed)) {
+            return '(el, arg) => { '.$trimmed.' }';
+        }
+
+        return $expression;
+    }
+
+    private static function isFunctionLike(string $s): bool
+    {
+        // Detect common JS function patterns: function, async function, arrow functions
+        return (bool) preg_match('/^((async\s+)?function\b|\([^)]*\)\s*=>|[A-Za-z_$][A-Za-z0-9_$]*\s*=>|async\s*\([^)]*\)\s*=>)/', $s);
+    }
+
+    private static function startsWithReturn(string $s): bool
+    {
+        return (bool) preg_match('/^return\b/', $s);
+    }
+
     /**
      * @param array<string, mixed> $options
      */

src/Page/Page.php

@@ -259,7 +259,8 @@ public function content(): ?string
 
     public function evaluate(string $expression, mixed $arg = null): mixed
     {
-        $response = $this->sendCommand('evaluate', ['expression' => $expression, 'arg' => $arg]);
+        $normalized = self::normalizeForPage($expression);
+        $response = $this->sendCommand('evaluate', ['expression' => $normalized, 'arg' => $arg]);
 
         return $response['result'] ?? null;
     }
@@ -751,6 +752,32 @@ private function createConsoleMessage(array $params): ConsoleMessage
         return new ConsoleMessage($params);
     }
 
+    private static function normalizeForPage(string $expression): string
+    {
+        $trimmed = ltrim($expression);
+
+        if (self::isFunctionLike($trimmed)) {
+            return $expression;
+        }
+
+        if (self::startsWithReturn($trimmed)) {
+            return '(arg) => { '.$trimmed.' }';
+        }
+
+        return $expression;
+    }
+
+    private static function isFunctionLike(string $s): bool
+    {
+        // Detect common JS function patterns: function, async function, arrow functions
+        return (bool) preg_match('/^((async\s+)?function\b|\([^)]*\)\s*=>|[A-Za-z_$][A-Za-z0-9_$]*\s*=>|async\s*\([^)]*\)\s*=>)/', $s);
+    }
+
+    private static function startsWithReturn(string $s): bool
+    {
+        return (bool) preg_match('/^return\b/', $s);
+    }
+
     /**
      * Helper method to validate transport data for Request creation.
      *

tests/Unit/Locator/LocatorEvaluateNormalizerTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the playwright-php/playwright package.
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace PlaywrightPHP\Tests\Unit\Locator;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use PlaywrightPHP\Locator\Locator;
+use PlaywrightPHP\Transport\TransportInterface;
+
+#[CoversClass(Locator::class)]
+final class LocatorEvaluateNormalizerTest extends TestCase
+{
+    public function testNormalizesReturnBodyToFunctionWithElement(): void
+    {
+        $transport = $this->createMock(TransportInterface::class);
+
+        $transport
+            ->expects($this->once())
+            ->method('send')
+            ->with($this->callback(function ($payload) {
+                return 'locator.evaluate' === $payload['action']
+                    && '(el, arg) => { return el.textContent; }' === $payload['expression'];
+            }))
+            ->willReturn(['value' => 'hello']);
+
+        $locator = new Locator($transport, 'page1', '.title');
+        $result = $locator->evaluate('return el.textContent;');
+        $this->assertSame('hello', $result);
+    }
+
+    public function testLeavesPlainExpressionUntouched(): void
+    {
+        $transport = $this->createMock(TransportInterface::class);
+
+        $transport
+            ->expects($this->once())
+            ->method('send')
+            ->with($this->callback(function ($payload) {
+                return 'locator.evaluate' === $payload['action']
+                    && 'element.textContent' === $payload['expression'];
+            }))
+            ->willReturn(['value' => 'ok']);
+
+        $locator = new Locator($transport, 'page1', '.title');
+        $result = $locator->evaluate('element.textContent');
+        $this->assertSame('ok', $result);
+    }
+}

tests/Unit/Page/PageEvaluateNormalizerTest.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the playwright-php/playwright package.
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace PlaywrightPHP\Tests\Unit\Page;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use PlaywrightPHP\Browser\BrowserContextInterface;
+use PlaywrightPHP\Page\Page;
+use PlaywrightPHP\Transport\TransportInterface;
+
+#[CoversClass(Page::class)]
+final class PageEvaluateNormalizerTest extends TestCase
+{
+    public function testNormalizesReturnBodyToFunction(): void
+    {
+        $transport = $this->createMock(TransportInterface::class);
+        $context = $this->createMock(BrowserContextInterface::class);
+
+        $transport
+            ->expects($this->once())
+            ->method('send')
+            ->with($this->callback(function ($payload) {
+                return 'page.evaluate' === $payload['action']
+                    && '(arg) => { return 42; }' === $payload['expression'];
+            }))
+            ->willReturn(['result' => 42]);
+
+        $page = new Page($transport, $context, 'p1');
+        $result = $page->evaluate('return 42;');
+        $this->assertSame(42, $result);
+    }
+
+    public function testLeavesPlainExpressionUntouched(): void
+    {
+        $transport = $this->createMock(TransportInterface::class);
+        $context = $this->createMock(BrowserContextInterface::class);
+
+        $transport
+            ->expects($this->once())
+            ->method('send')
+            ->with($this->callback(function ($payload) {
+                return 'page.evaluate' === $payload['action']
+                    && 'document.title' === $payload['expression'];
+            }))
+            ->willReturn(['result' => 'Hello']);
+
+        $page = new Page($transport, $context, 'p1');
+        $result = $page->evaluate('document.title');
+        $this->assertSame('Hello', $result);
+    }
+}