third_party/blink/web_tests/fast/canvas/canvas-large-pattern.html

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script>

test(function(t) {
    var canvas = document.createElement('canvas');
    canvas.width = 40000;
    var context = canvas.getContext('2d');
    context.fillStyle = '#0f0';
    context.fillRect(0, 0, 1, 1);

    var dstCanvas = document.createElement('canvas');
    var dstContext = dstCanvas.getContext('2d');
    var pattern = dstContext.createPattern(canvas, 'repeat');
    dstContext.fillStyle = pattern;
    dstContext.fillRect(0, 0, dstCanvas.width, dstCanvas.height);

    assert_array_equals(dstContext.getImageData(0, 0, 1, 1).data, [0, 255, 0, 255]);

    assert_array_equals(dstContext.getImageData(1, 0, 1, 1).data, [0, 0, 0, 0]);
    assert_array_equals(dstContext.getImageData(0, 1, 1, 1).data, [0, 0, 0, 0]);

}, 'Tests createPattern using a source image that is a canvas 40k pixels wide.');
</script>