[12.x] Add assertClientError method to TestResponse (#55750)

Author: shane-zeng

src/Illuminate/Testing/TestResponse.php

@@ -131,6 +131,21 @@ public function assertSuccessfulPrecognition()
         return $this;
     }
 
+    /**
+     * Assert that the response is a client error.
+     *
+     * @return $this
+     */
+    public function assertClientError()
+    {
+        PHPUnit::withResponse($this)->assertTrue(
+            $this->isClientError(),
+            $this->statusMessageWithDetails('>=400, < 500', $this->getStatusCode())
+        );
+
+        return $this;
+    }
+
     /**
      * Assert that the response is a server error.
      *

tests/Testing/TestResponseTest.php

@@ -1086,6 +1086,18 @@ public function testAssertUnprocessable()
         $response->assertUnprocessable();
     }
 
+    public function testAssertClientError()
+    {
+        $statusCode = 400;
+
+        $baseResponse = tap(new Response, function ($response) use ($statusCode) {
+            $response->setStatusCode($statusCode);
+        });
+
+        $response = TestResponse::fromBaseResponse($baseResponse);
+        $response->assertClientError();
+    }
+
     public function testAssertServerError()
     {
         $statusCode = 500;