1 files changed, 42 insertions, 0 deletions
diff --git a/testing/web-platform/tests/hr-time/resources/timing-attack.js b/testing/web-platform/tests/hr-time/resources/timing-attack.js
new file mode 100644
index 0000000000..f1fc786903
--- /dev/null
+++ b/testing/web-platform/tests/hr-time/resources/timing-attack.js
@@ -0,0 +1,42 @@
+function run_test(isolated) {
+  let resolution = 100;
+  if (isolated) {
+    resolution = 5;
+  }
+  test(function() {
+    function check_resolutions(times, length) {
+      const end = length - 2;
+
+      // we compare each value with the following ones
+      for (let i = 0; i < end; i++) {
+        const h1 = times[i];
+        for (let j = i+1; j < end; j++) {
+          const h2 = times[j];
+          const diff = h2 - h1;
+          assert_true((diff === 0) || ((diff * 1000) >= resolution),
+            "Differences smaller than ' + resolution + ' microseconds: " + diff);
+        }
+      }
+      return true;
+    }
+
+    const times = new Array(10);
+    let index = 0;
+    let hrt1, hrt2, hrt;
+    assert_equals(self.crossOriginIsolated, isolated, "Document cross-origin isolated value matches");
+
+    // rapid firing of performance.now
+    hrt1 = performance.now();
+    hrt2 = performance.now();
+    times[index++] = hrt1;
+    times[index++] = hrt2;
+
+    // ensure that we get performance.now() to return a different value
+    do {
+      hrt = performance.now();
+      times[index++] = hrt;
+    } while ((hrt - hrt1) === 0);
+
+    assert_true(check_resolutions(times, index), 'Difference should be at least ' + resolution + ' microseconds.');
+  }, 'The recommended minimum resolution of the Performance interface has been set to ' + resolution + ' microseconds for cross-origin isolated contexts.');
+}