1 files changed, 50 insertions, 0 deletions
diff --git a/testing/web-platform/tests/compute-pressure/compute_pressure_rate_obfuscation_mitigation_not_triggered.https.window.js b/testing/web-platform/tests/compute-pressure/compute_pressure_rate_obfuscation_mitigation_not_triggered.https.window.js
new file mode 100644
index 0000000000..e348a8ea08
--- /dev/null
+++ b/testing/web-platform/tests/compute-pressure/compute_pressure_rate_obfuscation_mitigation_not_triggered.https.window.js
@@ -0,0 +1,50 @@
+// 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 sampleIntervalInMs = 100;
+  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 minChangesThreshold = 50;
+
+  const changes = await new Promise(async resolve => {
+    const observerChanges = [];
+    const observer = new PressureObserver(changes => {
+      observerChanges.push(changes);
+    }, {sampleInterval: sampleIntervalInMs});
+
+    observer.observe('cpu');
+    mockPressureService.startPlatformCollector(sampleIntervalInMs);
+    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 < minChangesThreshold) {
+      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`);
+    }
+    observer.disconnect();
+    resolve(observerChanges);
+  });
+  assert_equals(changes.length, minChangesThreshold);
+
+  for (let i = 0; i < (changes.length - 1); i++) {
+    // Because no penalty should be triggered, the timestamp difference
+    // between samples should be less than the minimum penalty.
+    assert_less_than(
+        changes[i + 1][0].time - changes[i][0].time, minPenaltyTimeInMs,
+        'Not in sample time boundaries');
+  }
+}, 'No rate obfuscation mitigation should happen, when number of changes is below minimum changes before penalty');