/**
  * Test FilesystemHelper::rmDir().
  */
 public function testRmDir()
 {
     // Create a test directory containing some files in several levels.
     $testDir = $this->tempDir(true);
     // Check that the directory can be removed.
     $this->assertTrue($this->filesystemHelper->rmdir($testDir));
     $this->assertFileNotExists($testDir);
 }