feature #19322 [HttpFoundation] Add Request::isMethodIdempotent method (dunglas)

This PR was squashed before being merged into the 3.2-dev branch (closes #19322).

Discussion
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[HttpFoundation] Add Request::isMethodIdempotent method

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Addd a new method in the spirit of `isMethodSafe` to know if the current method is idempotent according to RFCs.

Commits
-------

44df6a4 [HttpFoundation] Add Request::isMethodIdempotent method

Author: fabpot

src/Symfony/Component/HttpFoundation/Request.php

@@ -1473,7 +1473,7 @@ public function isMethod($method)
     }
 
     /**
-     * Checks whether the method is safe or not.
+     * Checks whether or not the method is safe.
      *
      * @return bool
      */
@@ -1482,6 +1482,16 @@ public function isMethodSafe()
         return in_array($this->getMethod(), array('GET', 'HEAD'));
     }
 
+    /**
+     * Checks whether or not the method is idempotent.
+     *
+     * @return bool
+     */
+    public function isMethodIdempotent()
+    {
+        return in_array($this->getMethod(), array('HEAD', 'GET', 'PUT', 'DELETE', 'TRACE', 'OPTIONS', 'PURGE'));
+    }
+
     /**
      * Returns the request body content.
      *

src/Symfony/Component/HttpFoundation/Tests/RequestTest.php

@@ -1951,6 +1951,32 @@ public function getLongHostNames()
             array(str_repeat(':', 101)),
         );
     }
+
+    /**
+     * @dataProvider methodIdempotentProvider
+     */
+    public function testMethodIdempotent($method, $idempotent)
+    {
+        $request = new Request();
+        $request->setMethod($method);
+        $this->assertEquals($idempotent, $request->isMethodIdempotent());
+    }
+
+    public function methodIdempotentProvider()
+    {
+        return array(
+            array('HEAD', true),
+            array('GET', true),
+            array('POST', false),
+            array('PUT', true),
+            array('PATCH', false),
+            array('DELETE', true),
+            array('PURGE', true),
+            array('OPTIONS', true),
+            array('TRACE', true),
+            array('CONNECT', false),
+        );
+    }
 }
 
 class RequestContentProxy extends Request