[13.x] Add flushState to FormRequest to reset global strict mode between tests (#59574)

* [13.x] Add flushState to FormRequest to reset global strict mode between tests

FormRequest::failOnUnknownFields() sets a static flag that persists
across tests. Without a flushState() method and a call in the test
lifecycle teardown, enabling strict mode in one test leaks into all
subsequent tests.

* formatting

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

Author: sumaiazaman

src/Illuminate/Foundation/Http/FormRequest.php

@@ -427,4 +427,14 @@ public function setContainer(Container $container)
 
         return $this;
     }
+
+    /**
+     * Flush the global state of the form request.
+     *
+     * @return void
+     */
+    public static function flushState(): void
+    {
+        static::$globalFailOnUnknownFields = false;
+    }
 }

src/Illuminate/Foundation/Testing/Concerns/InteractsWithTestCaseLifecycle.php

@@ -11,6 +11,7 @@
 use Illuminate\Foundation\Bootstrap\HandleExceptions;
 use Illuminate\Foundation\Bootstrap\RegisterProviders;
 use Illuminate\Foundation\Console\AboutCommand;
+use Illuminate\Foundation\Http\FormRequest;
 use Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull;
 use Illuminate\Foundation\Http\Middleware\PreventRequestForgery;
 use Illuminate\Foundation\Http\Middleware\PreventRequestsDuringMaintenance;
@@ -183,6 +184,7 @@ protected function tearDownTheTestEnvironment(): void
         Component::forgetFactory();
         ConvertEmptyStringsToNull::flushState();
         Factory::flushState();
+        FormRequest::flushState();
         EncodedHtmlString::flushState();
         EncryptCookies::flushState();
         HandleCors::flushState();