Added check for filename in archive manager and added test

src/Composer/Package/Archiver/ArchiveManager.php

@@ -108,6 +108,9 @@ class ArchiveManager
         if (empty($format)) {
             throw new \InvalidArgumentException('Format must be specified');
         }
+        if(!is_null($fileName) && !is_string($fileName)) {
+            throw new \InvalidArgumentException('fileName must be a string');
+        }
 
         // Search for the most appropriate archiver
         $usableArchiver = null;
@@ -124,7 +127,11 @@ class ArchiveManager
         }
 
         $filesystem = new Filesystem();
+        if(null === $fileName) {
+            $packageName = $fileName;
+        } else {
             $packageName = $this->getPackageFilename($package);
+        }
 
         // Archive filename
         $filesystem->ensureDirectoryExists($targetDir);

tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php

@@ -13,11 +13,16 @@
 namespace Composer\Test\Package\Archiver;
 
 use Composer\Factory;
+use Composer\Package\Archiver\ArchiveManager;
 use Composer\Package\PackageInterface;
 
 class ArchiveManagerTest extends ArchiverTest
 {
+    /**
+     * @var ArchiveManager
+     */
     protected $manager;
+
     protected $targetDir;
 
     public function setUp()
@@ -55,9 +60,41 @@ class ArchiveManagerTest extends ArchiverTest
         unlink($target);
     }
 
-    protected function getTargetName(PackageInterface $package, $format)
+    public function testArchiveCustomFileName()
     {
+        $this->setupGitRepo();
+
+        $package = $this->setupPackage();
+
+        $fileName =  "testArchiveName";
+
+        $this->manager->archive($package, 'tar', $this->targetDir, $fileName);
+
+        $target = $this->getTargetName($package, 'tar', $fileName);
+
+        $this->assertFileExists($target);
+
+        $tmppath = sys_get_temp_dir().'/composer_archiver/'.$this->manager->getPackageFilename($package);
+        $this->assertFileNotExists($tmppath);
+
+        unlink($target);
+    }
+
+    public function testNonStringFileName() {
+        $this->setExpectedException("InvalidArgumentException");
+
+        $package = $this->setupPackage();
+
+        $this->manager->archive($package, 'tar', $this->targetDir, array());
+    }
+
+    protected function getTargetName(PackageInterface $package, $format, $fileName = null)
+    {
+        if(!is_null($fileName)) {
+            $packageName = $fileName;
+        } else {
             $packageName = $this->manager->getPackageFilename($package);
+        }
         $target = $this->targetDir.'/'.$packageName.'.'.$format;
 
         return $target;