/**
  * @expectedException PHPUnit_Framework_Error_Warning
  */
 function test__invalid_image_file()
 {
     $source = AMP_IMG_DIMENSION_TEST_INVALID_FILE;
     $expected = false;
     $dimensions = AMP_Image_Dimension_Extractor::extract_by_downloading_image(false, $source);
     $this->assertEquals($expected, $dimensions);
 }