1 files changed, 56 insertions, 0 deletions
diff --git a/testing/web-platform/tests/longtask-timing/containerNames.html b/testing/web-platform/tests/longtask-timing/containerNames.html
new file mode 100644
index 0000000000..e6a9335dc7
--- /dev/null
+++ b/testing/web-platform/tests/longtask-timing/containerNames.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<title>LongTask Timing: long tasks in long-name iframe containers</title>
+<body>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/utils.js"></script>
+<h1>Longtasks in iframe</h1>
+<div id="log"></div>
+<script>
+const longContainerName = 'iframeWithLongNameMoreThan100CharactersSpaceHolderSpaceHolderSpaceHolderSpaceHolderSpaceHolderSpaceHolder';
+
+promise_test(async t => {
+  assert_implements(window.PerformanceLongTaskTiming, 'Longtasks are not supported.');
+  const initialTime = performance.now();
+  const performanceObserverTimeout = 5 * 1000;
+  const longTasksPromise = new Promise(resolve => {
+    const observer = new PerformanceObserver(t.step_func(entryList => {
+      const entries = entryList.getEntries();
+      entries.forEach(longtask => {
+        assert_equals(longtask.entryType, 'longtask');
+        if (hasUnrelatedTaskName(longtask.name, 'same-origin-descendant')) {
+            return;
+        }
+        checkLongTaskEntry(longtask, 'same-origin-descendant');
+        // Assert the TaskAttributionTiming entry in attribution.
+        assert_equals(longtask.attribution.length, 1,
+            'Exactly one attribution entry is expected');
+        const attribution = longtask.attribution[0];
+        assert_equals(attribution.entryType, 'taskattribution');
+        assert_equals(attribution.name, 'unknown');
+        assert_equals(attribution.duration, 0);
+        assert_equals(attribution.startTime, 0);
+        assert_equals(attribution.containerId, longContainerName + '-id');
+        assert_equals(attribution.containerName, longContainerName + '-name');
+        assert_equals(attribution.containerSrc, 'resources/subframe-with-longtask.html');
+        observer.disconnect();
+        resolve();
+      })
+    }));
+    observer.observe({entryTypes: ['longtask']});
+    const iframe = document.createElement('iframe');
+    iframe.id = longContainerName + '-id';
+    iframe.name = longContainerName + '-name';
+    iframe.src = 'resources/subframe-with-longtask.html';
+    document.body.appendChild(iframe);
+  });
+  const timeout = new Promise(
+    (resolve, reject) => t.step_timeout(
+      () => { reject(new Error('observer failed to find any entries')) },
+      performanceObserverTimeout)
+  )
+  return Promise.race([longTasksPromise, timeout]);
+}, `Performance longtask entries in ${longContainerName} are observable in parent.`);
+</script>
+</body>