public function testFlush()
{
$streams = $this->provideStreams();
$executor = new Executor();
$this->assertSame(0, $executor->flush('echo foo', $streams));
rewind($streams[0]);
$this->assertSame('', fread($streams[0], 1024));
rewind($streams[1]);
$this->assertSame("foo\r\n", fread($streams[1], 1024));
rewind($streams[2]);
$this->assertSame('', fread($streams[2], 1024));
}