Merge branch '5.4' into 6.0

* 5.4:
  Minor reword
  Fix empty_data option description of TextareaType
  update mailer testing documentation
  Use when@dev insteadof dev/mailer.yaml

Author: javiereguiluz

mailer.rst

@@ -505,7 +505,7 @@ and headers.
 
     .. code-block:: yaml
 
-        # config/packages/dev/mailer.yaml
+        # config/packages/mailer.yaml
         framework:
             mailer:
                 envelope:
@@ -1360,10 +1360,11 @@ the mailer configuration file (e.g. in the ``dev`` or ``test`` environments):
 
     .. code-block:: yaml
 
-        # config/packages/dev/mailer.yaml
-        framework:
-            mailer:
-                dsn: 'null://null'
+        # config/packages/mailer.yaml
+        when@dev:
+            framework:
+                mailer:
+                    dsn: 'null://null'
 
     .. code-block:: xml
 
@@ -1408,11 +1409,12 @@ a specific address, instead of the *real* address:
 
     .. code-block:: yaml
 
-        # config/packages/dev/mailer.yaml
-        framework:
-            mailer:
-                envelope:
-                    recipients: ['youremail@example.com']
+        # config/packages/mailer.yaml
+        when@dev:
+            framework:
+                mailer:
+                    envelope:
+                        recipients: ['youremail@example.com']
 
     .. code-block:: xml
 
@@ -1451,22 +1453,22 @@ a specific address, instead of the *real* address:
 Write a Functional Test
 ~~~~~~~~~~~~~~~~~~~~~~~
 
-To functionally test that an email was sent, and even assert the email content or headers,
-you can use the built in assertions::
+Symfony provides lots of :ref:`built-in mailer assertions <mailer-assertions>`
+to functionally test that an email was sent, its contents or headers, etc.
+They are available in test classes extending
+:class:`Symfony\\Bundle\\FrameworkBundle\\Test\\KernelTestCase` or when using
+the :class:`Symfony\\Bundle\\FrameworkBundle\\Test\\MailerAssertionsTrait`::
 
     // tests/Controller/MailControllerTest.php
     namespace App\Tests\Controller;
 
-    use Symfony\Bundle\FrameworkBundle\Test\MailerAssertionsTrait;
     use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
 
     class MailControllerTest extends WebTestCase
     {
-        use MailerAssertionsTrait;
-
         public function testMailIsSentAndContentIsOk()
         {
-            $client = $this->createClient();
+            $client = static::createClient();
             $client->request('GET', '/mail/send');
             $this->assertResponseIsSuccessful();
 

reference/forms/types/textarea.rst

@@ -35,7 +35,9 @@ These options inherit from the :doc:`FormType </reference/forms/types/form>`:
 
 .. include:: /reference/forms/types/options/empty_data_declaration.rst.inc
 
-The default value is ``''`` (the empty string).
+From an HTTP perspective, submitted data is always a string or an array of strings.
+So by default, the form will treat any empty string as null. If you prefer to get
+an empty string, explicitly set the ``empty_data`` option to an empty string.
 
 .. include:: /reference/forms/types/options/empty_data_description.rst.inc
 

testing.rst

@@ -1039,6 +1039,8 @@ Crawler Assertions
     Asserts that value of the field of the first form matching the given
     selector does (not) equal the expected value.
 
+.. _mailer-assertions:
+
 Mailer Assertions
 .................