feature #43671 add ResponseIsUnprocessable (garak)

This PR was squashed before being merged into the 5.4 branch.

Discussion
----------

add ResponseIsUnprocessable

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | Fix #40894
| License       | MIT
| Doc PR        | none

Commits
-------

61df7f1752 add ResponseIsUnprocessable

Author: fabpot

Test/Constraint/ResponseIsUnprocessable.php

@@ -0,0 +1,56 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpFoundation\Test\Constraint;
+
+use PHPUnit\Framework\Constraint\Constraint;
+use Symfony\Component\HttpFoundation\Response;
+
+final class ResponseIsUnprocessable extends Constraint
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function toString(): string
+    {
+        return 'is unprocessable';
+    }
+
+    /**
+     * @param Response $other
+     *
+     * {@inheritdoc}
+     */
+    protected function matches($other): bool
+    {
+        return Response::HTTP_UNPROCESSABLE_ENTITY === $other->getStatusCode();
+    }
+
+    /**
+     * @param Response $other
+     *
+     * {@inheritdoc}
+     */
+    protected function failureDescription($other): string
+    {
+        return 'the Response '.$this->toString();
+    }
+
+    /**
+     * @param Response $other
+     *
+     * {@inheritdoc}
+     */
+    protected function additionalFailureDescription($other): string
+    {
+        return (string) $other;
+    }
+}

Tests/Test/Constraint/ResponseIsUnprocessableTest.php

@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpFoundation\Tests\Test\Constraint;
+
+use PHPUnit\Framework\ExpectationFailedException;
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\TestFailure;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpFoundation\Test\Constraint\ResponseIsUnprocessable;
+
+class ResponseIsUnprocessableTest extends TestCase
+{
+    public function testConstraint()
+    {
+        $constraint = new ResponseIsUnprocessable();
+
+        $this->assertTrue($constraint->evaluate(new Response('', 422), '', true));
+        $this->assertFalse($constraint->evaluate(new Response(), '', true));
+    }
+}