bug #12436 [Filesystem] Fixed case for empty folder (yosmanyga)

This PR was merged into the 2.3 branch.

Discussion
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[Filesystem] Fixed case for empty folder

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

The mirror function should work with an empty folder as source. It should create an empty folder on target path.

Commits
-------

5321741 Fixed case for empty folder

src/Symfony/Component/Filesystem/Filesystem.php

@@ -388,6 +388,10 @@ class Filesystem
             $iterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($originDir, $flags), \RecursiveIteratorIterator::SELF_FIRST);
         }
 
+        if ($this->exists($originDir)) {
+            $this->mkdir($targetDir);
+        }
+
         foreach ($iterator as $file) {
             $target = str_replace($originDir, $targetDir, $file->getPathname());
 

src/Symfony/Component/Filesystem/Tests/FilesystemTest.php

@@ -845,6 +845,21 @@ class FilesystemTest extends \PHPUnit_Framework_TestCase
         $this->assertFalse($this->filesystem->exists($targetPath.'directory'.DIRECTORY_SEPARATOR.'file1'));
     }
 
+    public function testMirrorCreatesEmptyDirectory()
+    {
+        $sourcePath = $this->workspace.DIRECTORY_SEPARATOR.'source'.DIRECTORY_SEPARATOR;
+
+        mkdir($sourcePath);
+
+        $targetPath = $this->workspace.DIRECTORY_SEPARATOR.'target'.DIRECTORY_SEPARATOR;
+
+        $this->filesystem->mirror($sourcePath, $targetPath);
+
+        $this->assertTrue(is_dir($targetPath));
+
+        $this->filesystem->remove($sourcePath);
+    }
+
     public function testMirrorCopiesLinks()
     {
         $this->markAsSkippedIfSymlinkIsMissing();