bug #19306 [Form] fixed bug - name in ButtonBuilder (cheprasov)

This PR was squashed before being merged into the 2.7 branch (closes #19306).

Discussion
----------

[Form] fixed bug - name in ButtonBuilder

| Q             | A
| ------------- | ---
| Branch?       |  2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? |no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

**Bug:**

For any scalar of name, expression `empty($name) && 0 != $name` is never true,
and as result - empty string ('') is allowed.

**Examples:**

```php
$name = ''; var_dump(empty($name) && 0 != $name); // false
$name = '0'; var_dump(empty($name) && 0 != $name); // false
$name = null; var_dump(empty($name) && 0 != $name); // false
$name = false; var_dump(empty($name) && 0 != $name); // false
$name = 0; var_dump(empty($name) && 0 != $name); // false
```

Commits
-------

f507023 [Form] fixed bug - name in ButtonBuilder

Author: fabpot

src/Symfony/Component/Form/ButtonBuilder.php

@@ -62,11 +62,12 @@ class ButtonBuilder implements \IteratorAggregate, FormBuilderInterface
      */
     public function __construct($name, array $options = array())
     {
-        if (empty($name) && 0 != $name) {
+        $name = (string) $name;
+        if ('' === $name) {
             throw new InvalidArgumentException('Buttons cannot have empty names.');
         }
 
-        $this->name = (string) $name;
+        $this->name = $name;
         $this->options = $options;
     }
 

src/Symfony/Component/Form/Tests/ButtonBuilderTest.php

@@ -0,0 +1,61 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Tests;
+
+use Symfony\Component\Form\ButtonBuilder;
+
+/**
+ * @author Alexander Cheprasov <[email protected]>
+ */
+class ButtonBuilderTest extends \PHPUnit_Framework_TestCase
+{
+    public function getValidNames()
+    {
+        return array(
+            array('reset'),
+            array('submit'),
+            array('foo'),
+            array('0'),
+            array(0),
+            array('button[]'),
+        );
+    }
+
+    /**
+     * @dataProvider getValidNames
+     */
+    public function testValidNames($name)
+    {
+        $this->assertInstanceOf('\Symfony\Component\Form\ButtonBuilder', new ButtonBuilder($name));
+    }
+
+    public function getInvalidNames()
+    {
+        return array(
+            array(''),
+            array(false),
+            array(null),
+        );
+    }
+
+    /**
+     * @dataProvider getInvalidNames
+     */
+    public function testInvalidNames($name)
+    {
+        $this->setExpectedException(
+            '\Symfony\Component\Form\Exception\InvalidArgumentException',
+            'Buttons cannot have empty names.'
+        );
+        new ButtonBuilder($name);
+    }
+}