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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /scheduler/tentative/yield/yield-inherit-across-settled-promises.any.html - WPT Dashboard Interop Dashboard
- /scheduler/tentative/yield/yield-inherit-across-settled-promises.any.worker.html - WPT Dashboard Interop Dashboard
'use strict';
// The scheduling state of the enclosing task must be inherited by
// continuations that descend from it through microtasks, regardless of how the
// microtask was created.
//
// HostMakeJobCallback captures the event loop's current continuation state
// unconditionally, and HostCallJobCallback restores it.
//
// Each test runs in a 'background' postTask task and runs a yield()
// continuation. As well, there is a 'user-visible' task posted just
// before the yield.
//
// If the scheduling state was inherited correctly, the continuation is
// 'background' and runs after the task. If the scheduling state is
// lost, the continuation gets the default 'user-visible' priority and
// runs before the 'background'.
function raceContinuationAgainstUserVisibleTask(ids) {
const task = scheduler.postTask(() => {
ids.push('task');
}, {priority: 'user-visible'});
return scheduler.yield().then(() => {
ids.push('continuation');
return task;
});
}
function inheritanceTest(name, body) {
promise_test(async t => {
const ids = [];
await scheduler.postTask(() => body(ids), {priority: 'background'});
assert_equals(ids.join(), 'task,continuation');
}, name);
}
inheritanceTest('yield() inherits priority with no intervening promise',
(ids) => raceContinuationAgainstUserVisibleTask(ids));
inheritanceTest('yield() inherits priority across a pending promise',
async (ids) => {
await new Promise(resolve => queueMicrotask(resolve));
await raceContinuationAgainstUserVisibleTask(ids);
});
// Already-settled promises.
inheritanceTest('yield() inherits priority across an await of a settled promise',
async (ids) => {
await Promise.resolve();
await raceContinuationAgainstUserVisibleTask(ids);
});
inheritanceTest('yield() inherits priority across an await of a non-promise',
async (ids) => {
await null;
await raceContinuationAgainstUserVisibleTask(ids);
});
inheritanceTest('yield() inherits priority in then() on a settled promise',
(ids) => Promise.resolve().then(
() => raceContinuationAgainstUserVisibleTask(ids)));
inheritanceTest('yield() inherits priority in a chained then() on a settled promise',
(ids) => Promise.resolve().then(() => {}).then(
() => raceContinuationAgainstUserVisibleTask(ids)));
inheritanceTest('yield() inherits priority across an await of a thenable',
async (ids) => {
await {then(resolve) { resolve(); }};
await raceContinuationAgainstUserVisibleTask(ids);
});
inheritanceTest('yield() inherits priority in a thenable then()',
(ids) => new Promise(resolve => resolve({
then(res) { res(raceContinuationAgainstUserVisibleTask(ids)); }
})));
inheritanceTest('yield() inherits priority across a promise resolved with a thenable',
async (ids) => {
await new Promise(resolve => resolve({then(r) { r(); }}));
await raceContinuationAgainstUserVisibleTask(ids);
});