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<!DOCTYPE html>
<meta charset="utf-8">
<title>Tests Stale While Revalidate works for images</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/utils.js"></script>
<body>
<!--
Use a child document to load the second stale image into because
an image loaded into the same document will skip cache-control headers.
See: https://html.spec.whatwg.org/#the-list-of-available-images
-->
<iframe id="child1" srcdoc=""></iframe>
<iframe id="child2" srcdoc=""></iframe>
<script>
var request_token = token();
let image_src = "resources/stale-image.py?token=" + request_token;
let loadImage = async (document) => {
let img = document.createElement("img");
img.src = image_src;
let loaded = new Promise(r => img.onload = r);
document.body.appendChild(img);
await loaded;
return img;
};
promise_test(async t => {
await new Promise(r => window.onload = r);
let img1 = await loadImage(document);
assert_equals(img1.width, 16, "(initial version loaded)");
let img2 = await loadImage(child1.contentDocument);
assert_equals(img2.width, 16, "(stale version loaded)");
// Query the server again and again. At some point it must have received the
// revalidation request. We poll, because we don't know when the revalidation
// will occur.
while(true) {
await new Promise(r => step_timeout(r, 25));
let response = await fetch(image_src + "&query");
let count = response.headers.get("Count");
if (count == '2')
break;
}
let img3 = await loadImage(child2.contentDocument);
assert_equals(img3.width, 256, "(revalidated version loaded)");
}, 'Cache returns stale resource');
</script>
</body>
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