public function testRewindUsesSeek()
{
$a = Psr7\stream_for('foo');
$d = $this->getMockBuilder('GuzzleHttp\\Psr7\\CachingStream')->setMethods(array('seek'))->setConstructorArgs(array($a))->getMock();
$d->expects($this->once())->method('seek')->with(0)->will($this->returnValue(true));
$d->seek(0);
}