PhpUnit image assert function

gistfile1.php

protected function assertImage($expected, $actual, $message = '')
{
	$descriptors = array(
		array('pipe', 'r'),
		array('pipe', 'w'),
		array('pipe', 'w'),
	);
	$command = 'compare -metric RMSE ' . escapeshellarg($expected) . ' ' . escapeshellarg($actual) . ' /dev/null';
	$proc = proc_open($command, $descriptors, $pipes);

	$diff = stream_get_contents($pipes[2]);
	fclose($pipes[0]);
	fclose($pipes[1]);
	fclose($pipes[2]);

	preg_match('#\((.+)\)#', $diff, $match);
	$threshold = floatval($match[1]);
	$this->assertLessThan(0.05, $threshold, $message);
}

Requires imagemagick installed (not PHP Imagick extension)

sudo apt-get install imagemagick