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setup(_ => {
assert_implements_optional(
document.createElement('link').relList.supports('prefetch'),
"Browser supports prefetch.");
assert_implements_optional(
"PerformanceResourceTiming" in window,
"Browser supports performance APIs.");
});
function assert_resource_not_downloaded(test, url) {
// CSP failures generate resource timing entries, so let's make sure that
// download sizes are 0.
const entries = performance.getEntriesByName(url, 'resource');
for (const entry of entries) {
assert_equals(entry.transferSize, 0, 'transferSize');
assert_equals(entry.encodedBodySize, 0, 'encodedBodySize');
assert_equals(entry.decodedBodySize, 0, 'decodedBodySize');
}
}
function assert_link_prefetches(test, link) {
assert_no_csp_event_for_url(test, link.href);
link.onerror = test.unreached_func('onerror should not fire.');
// Test is finished when either the `load` event fires, or we get a performance
// entry showing that the resource loaded successfully.
link.onload = test.step_func(test.step_func_done());
waitUntilResourceDownloaded(link.href).then(test.step_func_done());
document.head.appendChild(link);
}
function assert_link_does_not_prefetch(test, link) {
let cspEvent = false;
let errorEvent = false;
waitUntilCSPEventForURL(test, link.href)
.then(test.step_func(e => {
cspEvent = true;
assert_equals(e.violatedDirective, "prefetch-src");
assert_equals(e.effectiveDirective, "prefetch-src");
if (errorEvent)
test.done();
}));
link.onerror = test.step_func(e => {
errorEvent = true;
if (cspEvent)
test.done();
});
link.onload = test.unreached_func('onload should not fire.');
document.head.appendChild(link);
}
async function try_to_prefetch(href, test) {
const url = new URL(href, location.href);
url.searchParams.set(
'pipe',
'|header(Cache-Control, max-age=604800)' +
'|header(Access-Control-Allow-Origin, *)' +
'|header(Timing-Allow-Origin, *)');
url.searchParams.set('uuid', token());
const link = document.createElement('link');
link.rel = 'prefetch';
link.href = url.toString();
link.crossOrigin = 'anonymous';
test.add_cleanup(() => link.remove());
const didPrefetch = new Promise(resolve => {
const observer = new PerformanceObserver(list => {
const entries = list.getEntriesByName(link.href);
if (entries.length) {
resolve(entries[0]);
}
});
observer.observe({entryTypes: ['resource']})
});
document.head.appendChild(link);
const entry = await didPrefetch;
return entry.requestStart > 0 && entry.decodedBodySize > 0;
}