Fix Tool.php coverage and PHPStan errors in fixture

This commit addresses feedback on the previous submission:

1.  **Cover `\$value === null` branch in `Tool::validateType`**:
    - I added a new test case (`testValidateTypeWithNullForNonAnyTypes`)
      to `tests/Tool/ToolTest.php`.
    - This test specifically verifies that `validateType` returns `false`
      when a non-'any' type parameter (e.g., 'string', 'integer')
      is given a `null` value.

2.  **Resolve PHPStan errors in `tests/Tool/Fixture/ValidationTestTool.php`**:
    - I removed the `#[Parameter]` attributes from the `doExecute` method
      in `ValidationTestTool.php`.
    - These attributes were causing PHPStan errors as they were placed
      on a method instead of a parameter, and were not functionally
      required for the existing tests (which use reflection to set
      parameter metadata for `Tool::validateArguments` testing).

All PHPUnit tests, PHPCS, and PHPStan checks now pass.

Author: google-labs-jules[bot]

tests/Tool/Fixture/ValidationTestTool.php

@@ -10,12 +10,6 @@
 
 class ValidationTestTool extends Tool
 {
-    #[Parameter(name: 'pInt', type: 'integer', description: 'An integer parameter')]
-    #[Parameter(name: 'pObj', type: 'object', description: 'An object parameter')]
-    #[Parameter(name: 'pAny', type: 'any', description: 'A parameter of any type')]
-    #[Parameter(name: 'pOptInt', type: 'integer', description: 'An optional integer parameter', required: false)]
-    #[Parameter(name: 'pOptObj', type: 'object', description: 'An optional object parameter', required: false)]
-    #[Parameter(name: 'pOptAny', type: 'any', description: 'An optional parameter of any type', required: false)]
     protected function doExecute(array $arguments): ContentItemInterface
     {
         $results = [];

tests/Tool/ToolTest.php

@@ -626,4 +626,29 @@ public function testValidateArgumentsOptionalAnyTypeCorrect(): void
         $result = $tool->execute(['pInt' => 1, 'pObj' => new \stdClass(), 'pAny' => 'a']);
         $this->assertStringNotContainsString("pOptAny type", $result[0]['text']);
     }
+
+    public function testValidateTypeWithNullForNonAnyTypes(): void
+    {
+        $tool = new TestTool(); // Using TestTool, or any concrete Tool implementation
+        $reflectionMethod = new \ReflectionMethod(Tool::class, 'validateType');
+        $reflectionMethod->setAccessible(true);
+
+        $typesToTest = [
+            'string',
+            'number',
+            'integer',
+            'boolean',
+            'array',
+            'object',
+        ];
+
+        foreach ($typesToTest as $type) {
+            $isValid = $reflectionMethod->invoke($tool, null, $type);
+            $this->assertFalse($isValid, "validateType(null, '{$type}') should return false.");
+        }
+
+        // Also confirm 'any' type still accepts null
+        $isValidForAny = $reflectionMethod->invoke($tool, null, 'any');
+        $this->assertTrue($isValidForAny, "validateType(null, 'any') should return true.");
+    }
 }