1 files changed, 36 insertions, 0 deletions
diff --git a/testing/web-platform/tests/browsing-topics/resources/navigation-header-util.sub.js b/testing/web-platform/tests/browsing-topics/resources/navigation-header-util.sub.js
new file mode 100644
index 0000000000..b3bec79651
--- /dev/null
+++ b/testing/web-platform/tests/browsing-topics/resources/navigation-header-util.sub.js
@@ -0,0 +1,36 @@
+function test_topics_iframe_navigation_header(
+    test, has_browsing_topics_attribute, is_same_origin, expect_topics_header_available_func) {
+  const same_origin_src = '/browsing-topics/resources/check-topics-request-header-notify-parent.py';
+  const cross_origin_src = 'https://{{domains[www]}}:{{ports[https][0]}}' +
+    same_origin_src;
+
+  let frame = document.createElement('iframe');
+  frame.src = is_same_origin ? same_origin_src : cross_origin_src;
+
+  if (has_browsing_topics_attribute) {
+    frame.browsingTopics = true;
+  }
+
+  window.addEventListener('message', test.step_func(function handler(evt) {
+    if (evt.source === frame.contentWindow) {
+      expect_topics_header_available_func(evt.data);
+
+      document.body.removeChild(frame);
+      window.removeEventListener('message', handler);
+      test.done();
+    }
+  }));
+
+  document.body.appendChild(frame);
+}
+
+function expect_topics_header_unavailable(data) {
+  assert_equals(data.topicsHeader, 'NO_TOPICS_HEADER');
+}
+
+function expect_topics_header_available(data) {
+  // An empty result indicates that the request was eligible for topics.
+  // Currently, the web-platform-tests framework does not support actually
+  // handling the topics request.
+  assert_equals(data.topicsHeader, '');
+}
+\ No newline at end of file