Almost finished adding --file option, need to add unit test

src/Composer/Command/ArchiveCommand.php

@@ -42,6 +42,7 @@ class ArchiveCommand extends Command
                 new InputArgument('version', InputArgument::OPTIONAL, 'A version constraint to find the package to archive'),
                 new InputOption('format', 'f', InputOption::VALUE_OPTIONAL, 'Format of the resulting archive: tar or zip'),
                 new InputOption('dir', false, InputOption::VALUE_OPTIONAL, 'Write the archive to this directory'),
+                new InputOption('file', false, InputOption::VALUE_OPTIONAL, 'Write the archive with the given file name.'),
             ))
             ->setHelp(<<<EOT
 The <info>archive</info> command creates an archive of the specified format
@@ -78,7 +79,8 @@ EOT
             $input->getArgument('package'),
             $input->getArgument('version'),
             $input->getOption('format'),
-            $input->getOption('dir')
+            $input->getOption('dir'),
+            $input->getOption("file")
         );
 
         if (0 === $returnCode && $composer) {
@@ -88,7 +90,7 @@ EOT
         return $returnCode;
     }
 
-    protected function archive(IOInterface $io, Config $config, $packageName = null, $version = null, $format = 'tar', $dest = '.')
+    protected function archive(IOInterface $io, Config $config, $packageName = null, $version = null, $format = 'tar', $dest = '.', $fileName = null)
     {
         $factory = new Factory;
         $downloadManager = $factory->createDownloadManager($io, $config);
@@ -105,7 +107,7 @@ EOT
         }
 
         $io->writeError('<info>Creating the archive into "'.$dest.'".</info>');
-        $packagePath = $archiveManager->archive($package, $format, $dest);
+        $packagePath = $archiveManager->archive($package, $format, $dest, $fileName);
         $fs = new Filesystem;
         $shortPath = $fs->findShortestPath(getcwd(), $packagePath, true);
 

src/Composer/Package/Archiver/ArchiveManager.php

@@ -96,12 +96,14 @@ class ArchiveManager
      *
      * @param  PackageInterface          $package   The package to archive
      * @param  string                    $format    The format of the archive (zip, tar, ...)
-     * @param  string                    $targetDir The diretory where to build the archive
+     * @param  string                    $targetDir The directory where to build the archive
+     * @param  string|null               $fileName  The file name to use for the archive, or null to use the generated
+     *                                              package name
      * @throws \InvalidArgumentException
      * @throws \RuntimeException
      * @return string                    The path of the created archive
      */
-    public function archive(PackageInterface $package, $format, $targetDir)
+    public function archive(PackageInterface $package, $format, $targetDir, $fileName = null)
     {
         if (empty($format)) {
             throw new \InvalidArgumentException('Format must be specified');