| // META: timeout=long |
| // META: script=/resources/test-only-api.js |
| // META: script=resources/pressure-helpers.js |
| // META: global=window,dedicatedworker,sharedworker |
| |
| 'use strict'; |
| |
| pressure_test(async (t, mockPressureService) => { |
| const sampleRateInHz = 25; |
| const readings = ['nominal', 'fair', 'serious', 'critical']; |
| // Normative values for rate obfuscation parameters. |
| // https://w3c.github.io/compute-pressure/#rate-obfuscation-normative-parameters. |
| const minPenaltyTimeInMs = 5000; |
| const maxChangesThreshold = 100; |
| const minChangesThreshold = 50; |
| let gotPenalty = false; |
| await new Promise(async resolve => { |
| const observerChanges = []; |
| const observer = new PressureObserver(changes => { |
| if (observerChanges.length >= (minChangesThreshold - 1)) { |
| const lastSample = observerChanges.at(-1); |
| if ((changes[0].time - lastSample[0].time) >= minPenaltyTimeInMs) { |
| // The update delivery might still be working even if |
| // maxChangesThreshold have been reached and before disconnect() is |
| // processed. |
| // Therefore we are adding a flag to dismiss any updates after the |
| // penalty is detected, which is the condition for the test to pass. |
| gotPenalty = true; |
| observer.disconnect(); |
| resolve(); |
| } |
| } |
| observerChanges.push(changes); |
| }, {sampleRate: sampleRateInHz}); |
| |
| observer.observe('cpu'); |
| mockPressureService.startPlatformCollector(sampleRateInHz); |
| let i = 0; |
| // mockPressureService.updatesDelivered() does not necessarily match |
| // pressureChanges.length, as system load and browser optimizations can |
| // cause the actual timer used by mockPressureService to deliver readings |
| // to be a bit slower or faster than requested. |
| while (observerChanges.length <= maxChangesThreshold || !gotPenalty) { |
| mockPressureService.setPressureUpdate( |
| 'cpu', readings[i++ % readings.length]); |
| // Allow tasks to run (avoid a micro-task loop). |
| await new Promise((resolve) => t.step_timeout(resolve, 0)); |
| await t.step_wait( |
| () => mockPressureService.updatesDelivered() >= i, |
| `At least ${i} readings have been delivered`); |
| } |
| |
| assert_true(gotPenalty, 'Penalty not triggered'); |
| |
| }); |
| }, 'Rate obfuscation mitigation should have been triggered, when changes is higher than minimum changes before penalty'); |