public function testConstructor()
 {
     $dompdf = new Dompdf();
     $this->assertInstanceOf('Dompdf\\Adapter\\Cpdf', $dompdf->getCanvas());
     $this->assertEquals('', $dompdf->getBaseHost());
     $this->assertEquals('', $dompdf->getBasePath());
     $this->assertInternalType('array', $dompdf->getCallbacks());
     $this->assertInstanceOf('Dompdf\\Css\\Stylesheet', $dompdf->getCss());
     $this->assertNull($dompdf->getDom());
     $this->assertNull($dompdf->getHttpContext());
     $this->assertInstanceOf('Dompdf\\Options', $dompdf->getOptions());
     $this->assertNull($dompdf->getProtocol());
     $this->assertFalse($dompdf->getQuirksmode());
     $this->assertNull($dompdf->getTree());
 }