bug #16959 [Form] fix #15544 when a collection type attribute "required" is false, "prototype" should too (HeahDude)

This PR was squashed before being merged into the 2.3 branch (closes #16959).

Discussion
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[Form] fix #15544 when a collection type attribute "required" is false, "prototype" should too

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #15544
| License       | MIT
| Doc PR        | -

Commits
-------

b4b5d63 [Form] fix #15544 when a collection type attribute "required" is false, "prototype" should too

Author: fabpot

Extension/Core/Type/CollectionType.php

@@ -28,6 +28,7 @@ public function buildForm(FormBuilderInterface $builder, array $options)
     {
         if ($options['allow_add'] && $options['prototype']) {
             $prototype = $builder->create($options['prototype_name'], $options['type'], array_replace(array(
+                'required' => $options['required'],
                 'label' => $options['prototype_name'].'label__',
             ), $options['options']));
             $builder->setAttribute('prototype', $prototype->getForm());

Tests/Extension/Core/Type/CollectionTypeTest.php

@@ -195,4 +195,30 @@ public function testPrototypeDefaultLabel()
 
         $this->assertSame('__test__label__', $form->createView()->vars['prototype']->vars['label']);
     }
+
+    public function testPrototypeDefaultRequired()
+    {
+        $form = $this->factory->create('collection', array(), array(
+            'type' => 'file',
+            'allow_add' => true,
+            'prototype' => true,
+            'prototype_name' => '__test__',
+        ));
+
+        $this->assertTrue($form->createView()->vars['prototype']->vars['required']);
+    }
+
+    public function testPrototypeSetNotRequired()
+    {
+        $form = $this->factory->create('collection', array(), array(
+            'type' => 'file',
+            'allow_add' => true,
+            'prototype' => true,
+            'prototype_name' => '__test__',
+            'required' => false,
+        ));
+
+        $this->assertFalse($form->createView()->vars['required'], 'collection is not required');
+        $this->assertFalse($form->createView()->vars['prototype']->vars['required'], '"prototype" should not be required');
+    }
 }