public function appendContentIfOpenedWithModeA()
{
$vfsFile = vfsStream::url('foo/overwrite.txt');
file_put_contents($vfsFile, 'test');
$fp = fopen($vfsFile, 'ab');
fwrite($fp, 'd');
fclose($fp);
$this->assertEquals('testd', file_get_contents($vfsFile));
}