Added better messages and fixed bugs

src/Composer/Command/ArchiveCommand.php

@@ -42,7 +42,8 @@ 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.'),
+                new InputOption('file', false, InputOption::VALUE_OPTIONAL, 'Write the archive with the given file name.'
+                    .' Note that the format will be appended.'),
             ))
             ->setHelp(<<<EOT
 The <info>archive</info> command creates an archive of the specified format

src/Composer/Package/Archiver/ArchiveManager.php

@@ -97,8 +97,8 @@ class ArchiveManager
      * @param  PackageInterface          $package   The package to archive
      * @param  string                    $format    The format of the archive (zip, tar, ...)
      * @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
+     * @param  string|null               $fileName  The relative file name to use for the archive, or null to generate
-     *                                              package name
+     *                                   the package name. Note that the format will be appended to this name
      * @throws \InvalidArgumentException
      * @throws \RuntimeException
      * @return string                    The path of the created archive
@@ -128,9 +128,9 @@ class ArchiveManager
 
         $filesystem = new Filesystem();
         if(null === $fileName) {
-            $packageName = $fileName;
-        } else {
             $packageName = $this->getPackageFilename($package);
+        } else {
+            $packageName = $fileName;
         }
 
         // Archive filename

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

@@ -70,7 +70,7 @@ class ArchiveManagerTest extends ArchiverTest
 
         $this->manager->archive($package, 'tar', $this->targetDir, $fileName);
 
-        $target = $this->getTargetName($package, 'tar', $fileName);
+        $target =  $this->targetDir . "/" . $fileName . ".tar";
 
         $this->assertFileExists($target);
 
@@ -90,11 +90,12 @@ class ArchiveManagerTest extends ArchiverTest
 
     protected function getTargetName(PackageInterface $package, $format, $fileName = null)
     {
-        if(!is_null($fileName)) {
+        if(null === $fileName) {
-            $packageName = $fileName;
-        } else {
             $packageName = $this->manager->getPackageFilename($package);
+        } else {
+            $packageName = $fileName;
         }
+
         $target = $this->targetDir.'/'.$packageName.'.'.$format;
 
         return $target;