public function saveDoesNotOverwriteExistingHeaderCommentsIfFileExists()
{
$pathAndFilename = vfsStream::url('testDirectory') . '/YAMLConfiguration';
$comment = '# This comment should stay' . chr(10) . 'Test: foo' . chr(10);
file_put_contents($pathAndFilename . '.yaml', $comment);
$configurationSource = new YamlSource();
$configurationSource->save($pathAndFilename, ['configurationFileHasBeenLoaded' => true]);
$yaml = file_get_contents($pathAndFilename . '.yaml');
$this->assertContains('# This comment should stay' . chr(10) . chr(10), $yaml, 'Header comment was removed from file.');
$this->assertNotContains('Test: foo', $yaml);
}