| async_test(function (t) { |
| assert_precondition(window.PerformanceLongTaskTiming, 'Longtasks are not supported.'); |
| new PerformanceObserver( |
| t.step_func_done(entryList => { |
| const entries = entryList.getEntries(); |
| assert_equals(entries.length, 1, |
| 'Exactly one entry is expected.'); |
| const longtask = entries[0]; |
| assert_equals(longtask.entryType, 'longtask'); |
| assert_equals(longtask.name, 'self'); |
| assert_greater_than(longtask.duration, 50); |
| assert_greater_than_equal(longtask.startTime, 0); |
| const currentTime = performance.now(); |
| assert_less_than_equal(longtask.startTime, currentTime); |
| t.done(); |
| }) |
| ).observe({entryTypes: ['longtask']}); |
| |
| window.onload = () => { |
| /* Generate a slow microtask */ |
| Promise.resolve().then(() => { |
| const begin = window.performance.now(); |
| while (window.performance.now() < begin + 60); |
| }); |
| }; |
| }, 'A short task followed by a long microtask is observable.'); |