merged branch romainneutron/process-builder-prefix (PR #7584)

This PR was merged into the master branch.

Discussion
----------

[Process] Add ProcessBuilder::setPrefix method

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

This introduce a new feature for the `ProcessBuilder` that allows to prefix all generated `Process` commands with a custom value.
This is mostly useful when dealing with binary drivers.

Use case :

```php
use Symfony\Component\Process\ExecutableFinder;
use Symfony\Component\Process\ProcessBuilder;

class PhpDriver
{
    private $pb;

    public function __construct(ProcessBuilder $pb)
    {
        $this->pb = $pb;
    }

    public function getInfos()
    {
        return $this->execute('-i');
    }

    public function getVersion()
    {
        return $this->execute('-v');
    }

    private function execute(array $arguments)
    {
        return $this
            ->pb
            ->setArguments($arguments)
            ->createProcess()
            ->run()
            ->getOutput();
    }
}

$finder = new ExecutableFinder();

$pb = new ProcessBuilder();
$pb->setPrefix($finder->find('php'));

$driver = new PhpDriver($pb);
$driver->getVersion();
$driver->getInfos();
```

Commits
-------

cab53ee Add ProcessBuilder::setPrefix method

src/Symfony/Component/Process/ProcessBuilder.php

@@ -28,6 +28,7 @@ class ProcessBuilder
     private $timeout;
     private $options;
     private $inheritEnv;
+    private $prefix;
 
     public function __construct(array $arguments = array())
     {
@@ -58,6 +59,22 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Adds an unescaped prefix to the command string.
+     *
+     * The prefix is preserved when reseting arguments.
+     *
+     * @param string $prefix A command prefix
+     *
+     * @return ProcessBuilder
+     */
+    public function setPrefix($prefix)
+    {
+        $this->prefix = $prefix;
+
+        return $this;
+    }
+
     /**
      * @param array $arguments
      *
@@ -143,7 +160,8 @@ class ProcessBuilder
 
         $options = $this->options;
 
-        $script = implode(' ', array_map('escapeshellarg', $this->arguments));
+        $script = ($this->prefix ? escapeshellarg($this->prefix) . ' ' : '')
+            . implode(' ', array_map('escapeshellarg', $this->arguments));
 
         if ($this->inheritEnv) {
             $env = $this->env ? $this->env + $_ENV : null;

src/Symfony/Component/Process/Tests/ProcessBuilderTest.php

@@ -115,4 +115,16 @@ class ProcessBuilderTest extends \PHPUnit_Framework_TestCase
 
         $this->assertContains("second", $proc->getCommandLine());
     }
+
+    public function testPrefixIsPrependedToAllGeneratedProcess()
+    {
+        $pb = new ProcessBuilder();
+        $pb->setPrefix('/usr/bin/php');
+
+        $proc = $pb->setArguments(array('-v'))->getProcess();
+        $this->assertEquals("'/usr/bin/php' '-v'", $proc->getCommandLine());
+
+        $proc = $pb->setArguments(array('-i'))->getProcess();
+        $this->assertEquals("'/usr/bin/php' '-i'", $proc->getCommandLine());
+    }
 }