[8.x] Add unprocessable test response assertion (laravel#38553)

* Add assertUnprocessable method
* Add test

Co-authored-by: Joby Harding <code@jobyharding.com>

src/Illuminate/Testing/TestResponse.php

@@ -154,6 +154,16 @@ public function assertUnauthorized()
         return $this->assertStatus(401);
     }
 
+    /**
+     * Assert that the response has a 422 status code.
+     *
+     * @return $this
+     */
+    public function assertUnprocessable()
+    {
+        return $this->assertStatus(422);
+    }
+
     /**
      * Assert that the response has the given status code.
      *

tests/Testing/TestResponseTest.php

@@ -472,6 +472,22 @@ public function testAssertUnauthorized()
         $response->assertUnauthorized();
     }
 
+    public function testAssertUnprocessable()
+    {
+        $statusCode = 500;
+
+        $this->expectException(AssertionFailedError::class);
+
+        $this->expectExceptionMessage('Expected response status code');
+
+        $baseResponse = tap(new Response, function ($response) use ($statusCode) {
+            $response->setStatusCode($statusCode);
+        });
+
+        $response = TestResponse::fromBaseResponse($baseResponse);
+        $response->assertUnprocessable();
+    }
+
     public function testAssertNoContentAsserts204StatusCodeByDefault()
     {
         $statusCode = 500;