bug #15223 [Finder] Command::addAtIndex() fails with Command instance argument (thunderer)

This PR was squashed before being merged into the 2.3 branch (closes #15223).

Discussion
----------

[Finder] Command::addAtIndex() fails with Command instance argument

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #14384
| License       | MIT
| Doc PR        | -

Fixed reported bug #14384 and added test case for it. This is a second PR as previous #14385 went bad after I failed to rebase 2.3 branch properly.

Commits
-------

2aff566 [Finder] Command::addAtIndex() fails with Command instance argument

src/Symfony/Component/Finder/Shell/Command.php

@@ -289,7 +289,7 @@ class Command
      */
     public function addAtIndex($bit, $index)
     {
-        array_splice($this->bits, $index, 0, $bit);
+        array_splice($this->bits, $index, 0, $bit instanceof self ? array($bit) : $bit);
 
         return $this;
     }

src/Symfony/Component/Finder/Tests/Shell/CommandTest.php

@@ -0,0 +1,162 @@
+<?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\Finder\Tests\Shell;
+
+use Symfony\Component\Finder\Shell\Command;
+
+class CommandTest extends \PHPUnit_Framework_TestCase
+{
+    public function testCreate()
+    {
+        $this->assertInstanceOf('Symfony\Component\Finder\Shell\Command', Command::create());
+    }
+
+    public function testAdd()
+    {
+        $cmd = Command::create()->add('--force');
+        $this->assertSame('--force', $cmd->join());
+    }
+
+    public function testAddAsFirst()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->addAtIndex(Command::create()->add('-F'), 0);
+        $this->assertSame('-F --force', $cmd->join());
+    }
+
+    public function testAddAsLast()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->addAtIndex(Command::create()->add('-F'), 1);
+        $this->assertSame('--force -F', $cmd->join());
+    }
+
+    public function testAddInBetween()
+    {
+        $cmd = Command::create()->add('--force');
+        $cmd->addAtIndex(Command::create()->add('-F'), 0);
+
+        $cmd->addAtIndex(Command::create()->add('-X'), 1);
+        $this->assertSame('-F -X --force', $cmd->join());
+    }
+
+    public function testCount()
+    {
+        $cmd = Command::create();
+        $this->assertSame(0, $cmd->length());
+
+        $cmd->add('--force');
+        $this->assertSame(1, $cmd->length());
+
+        $cmd->add('--run');
+        $this->assertSame(2, $cmd->length());
+    }
+
+    public function testTop()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->top('--run');
+        $this->assertSame('--run --force', $cmd->join());
+    }
+
+    public function testTopLabeled()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->top('--run');
+        $cmd->ins('--something');
+        $cmd->top('--something');
+        $this->assertSame('--something --run --force ', $cmd->join());
+    }
+
+    public function testArg()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->arg('--run');
+        $this->assertSame('--force \'--run\'', $cmd->join());
+    }
+
+    public function testCmd()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->cmd('run');
+        $this->assertSame('--force run', $cmd->join());
+    }
+
+    public function testInsDuplicateLabelException()
+    {
+        $cmd = Command::create()->add('--force');
+
+        $cmd->ins('label');
+        $this->setExpectedException('RuntimeException');
+        $cmd->ins('label');
+    }
+
+    public function testEnd()
+    {
+        $parent = Command::create();
+        $cmd = Command::create($parent);
+
+        $this->assertSame($parent, $cmd->end());
+    }
+
+    public function testEndNoParentException()
+    {
+        $cmd = Command::create();
+
+        $this->setExpectedException('RuntimeException');
+        $cmd->end();
+    }
+
+    public function testGetMissingLabelException()
+    {
+        $cmd = Command::create();
+
+        $this->setExpectedException('RuntimeException');
+        $cmd->get('invalid');
+    }
+
+    public function testErrorHandler()
+    {
+        $cmd = Command::create();
+        $handler = function() { return 'error-handler'; };
+        $cmd->setErrorHandler($handler);
+
+        $this->assertSame($handler, $cmd->getErrorHandler());
+    }
+
+    public function testExecute()
+    {
+        $cmd = Command::create();
+        $cmd->add('php');
+        $cmd->add('--version');
+        $result = $cmd->execute();
+
+        $this->assertTrue(is_array($result));
+        $this->assertNotEmpty($result);
+        $this->assertRegexp('/PHP|HipHop/', $result[0]);
+    }
+
+    public function testCastToString()
+    {
+        $cmd = Command::create();
+        $cmd->add('--force');
+        $cmd->add('--run');
+
+        $this->assertSame('--force --run', (string) $cmd);
+    }
+}