1 files changed, 44 insertions, 0 deletions
diff --git a/testing/web-platform/tests/performance-timeline/performanceobservers.js b/testing/web-platform/tests/performance-timeline/performanceobservers.js
new file mode 100644
index 0000000000..3f357374ef
--- /dev/null
+++ b/testing/web-platform/tests/performance-timeline/performanceobservers.js
@@ -0,0 +1,44 @@
+// Compares a performance entry to a predefined one
+// perfEntriesToCheck is an array of performance entries from the user agent
+// expectedEntries is an array of performance entries minted by the test
+function checkEntries(perfEntriesToCheck, expectedEntries) {
+  function findMatch(pe) {
+    // we match based on entryType and name
+    for (var i = expectedEntries.length - 1; i >= 0; i--) {
+      var ex = expectedEntries[i];
+      if (ex.entryType === pe.entryType && ex.name === pe.name) {
+        return ex;
+      }
+    }
+    return null;
+  }
+
+  assert_equals(perfEntriesToCheck.length, expectedEntries.length, "performance entries must match");
+
+  perfEntriesToCheck.forEach(function (pe1) {
+    assert_not_equals(findMatch(pe1), null, "Entry matches");
+  });
+}
+
+// Waits for performance.now to advance. Since precision reduction might
+// cause it to return the same value across multiple calls.
+function wait() {
+  var now = performance.now();
+  while (now === performance.now())
+    continue;
+}
+
+// Ensure the entries list is sorted by startTime.
+function checkSorted(entries) {
+  assert_not_equals(entries.length, 0, "entries list must not be empty");
+  if (!entries.length)
+    return;
+
+  var sorted = false;
+  var lastStartTime = entries[0].startTime;
+  for (var i = 1; i < entries.length; ++i) {
+    var currStartTime = entries[i].startTime;
+    assert_less_than_equal(lastStartTime, currStartTime, "entry list must be sorted by startTime");
+    lastStartTime = currStartTime;
+  }
+}