<!DOCTYPE html>
<html>
<body>
<script src="../../resources/js-test-pre.js"></script>
<script>
description("Test the behavior when assigning null to context.globalCompositeOperation");

var canvas = document.createElement("canvas");
canvas.width = 200;
canvas.height = 200;
var context = canvas.getContext("2d");
// Initial operation should be "source-over".
shouldBeEqualToString("context.globalCompositeOperation", "source-over");

// Setting to 'copy' should work as this is a valid operation.
shouldNotThrow("context.globalCompositeOperation = 'copy'");
shouldBeEqualToString("context.globalCompositeOperation", "copy");

// Assignment to null should be ignored because "null" is not a valid operation.
shouldNotThrow("context.globalCompositeOperation = null");
shouldBeEqualToString("context.globalCompositeOperation", "copy");

// Assignment to "" should be ignored because "" is not a valid operation.
shouldNotThrow("context.globalCompositeOperation = ''");
shouldBeEqualToString("context.globalCompositeOperation", "copy");
</script>
<script src="../../resources/js-test-post.js"></script>
</body>
</html>