diff --git a/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/named-lookup-scoped-to-browsing-context-group.html b/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/named-lookup-scoped-to-browsing-context-group.html
new file mode 100644
index 0000000000000..0450d479196a1
--- /dev/null
+++ b/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/named-lookup-scoped-to-browsing-context-group.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<title>Named lookup scoped to browsing context group</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/utils.js"></script>
+<script src="/common/dispatcher/dispatcher.js"></script>
+<script src="/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js"></script>
+
+<body>
+<script>
+
+promise_test(async t => {
+  const rcHelper = new RemoteContextHelper();
+  // This test harness cannot be in the same browsing context group as the
+  // popup.
+  const rcPopup1 = await rcHelper.addWindow(undefined, { features: 'noopener' });
+
+  await rcPopup1.executeScript(() => {
+    window.name = 'my_popup';
+    window.firstPopup = true;
+  });
+  assert_equals(window.open('', 'my_popup').firstPopup, undefined,
+                'cannot lookup across browsing context groups');
+}, 'named lookup scoped to browsing context group');
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/no-proactive-swap-when-other-contexts-in-group.html b/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/no-proactive-swap-when-other-contexts-in-group.html
new file mode 100644
index 0000000000000..5f4e0da690b93
--- /dev/null
+++ b/testing/web-platform/tests/html/browsers/windows/auxiliary-browsing-contexts/no-proactive-swap-when-other-contexts-in-group.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<title>No proactive browsing context group changes when other contexts in group</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/utils.js"></script>
+<script src="/common/dispatcher/dispatcher.js"></script>
+<script src="/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js"></script>
+
+<body>
+<script>
+
+promise_test(async t => {
+  const rcHelper = new RemoteContextHelper();
+  const rcPopup1 = await rcHelper.addWindow(undefined, { target: 'my_popup' });
+
+  await rcPopup1.executeScript(() => {
+    window.intendedTarget1 = true;
+  });
+  assert_true(window.open('', 'my_popup').intendedTarget1,
+              'lookup by name');
+
+  // There is no security reason (e.g. COOP) to change browsing context groups
+  // for this navigation. Some implementations perform BCG swaps for performance
+  // reasons, but they cannot do so in this case, as this test harness page and
+  // the popup are in the same browsing context group.
+  const rcPopup2 = await rcPopup1.navigateToNew();
+
+  // In order to find the popup by name, the popup and this opener must be in
+  // the same browsing context group.
+  await rcPopup2.executeScript(() => {
+    window.intendedTarget2 = true;
+  });
+  assert_true(window.open('', 'my_popup').intendedTarget2,
+              'lookup by name after navigation');
+}, 'no proactive browsing context group change when other contexts in group');
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/html/browsers/windows/browsing-context-names/duplicate-name-order.html b/testing/web-platform/tests/html/browsers/windows/browsing-context-names/duplicate-name-order.html
new file mode 100644
index 0000000000000..95b461d4edde7
--- /dev/null
+++ b/testing/web-platform/tests/html/browsers/windows/browsing-context-names/duplicate-name-order.html
@@ -0,0 +1,55 @@
+<!DOCTYPE html>
+<title>Duplicate name lookup order</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/utils.js"></script>
+<script src="/common/dispatcher/dispatcher.js"></script>
+<script src="/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js"></script>
+
+<body>
+<script>
+
+promise_test(async t => {
+  const rcHelper = new RemoteContextHelper();
+  const rcMain = await rcHelper.addWindow();
+
+  const rcPopupA = await rcHelper.addWindow(undefined, { target: 'A' });
+  const rcPopupB = await rcHelper.addWindow(undefined, { target: 'B' });
+  const rcPopupC = await rcHelper.addWindow(undefined, { target: 'C' });
+
+  const rcSiblingA = await rcMain.addIframe(undefined, { name: 'A' });
+  const rcSiblingB = await rcMain.addIframe(undefined, { name: 'B' });
+
+  const rcRequestor = await rcMain.addIframe();
+
+  const rcChildA = await rcRequestor.addIframe(undefined, { name: 'A' });
+
+  const windowIdentifiers = {
+   'Main': rcMain,
+   'PopupA': rcPopupA,
+   'PopupB': rcPopupB,
+   'PopupC': rcPopupC,
+   'SiblingA': rcSiblingA,
+   'SiblingB': rcSiblingB,
+   'Requestor': rcRequestor,
+   'ChildA': rcChildA,
+  };
+  for (const [windowIdentifier, remote] of Object.entries(windowIdentifiers)) {
+    await remote.executeScript((windowIdentifier) => {
+      window.windowIdentifier = windowIdentifier;
+    }, [windowIdentifier]);
+  }
+
+  function performLookup(targetName) {
+    return rcRequestor.executeScript((targetName) => {
+        return window.open('', targetName).windowIdentifier;
+      }, [targetName]);
+  }
+
+  assert_equals(await performLookup('A'), 'ChildA', 'subtree first');
+  assert_equals(await performLookup('B'), 'SiblingB', 'then the rest of the tree');
+  assert_equals(await performLookup('C'), 'PopupC', 'then other pages');
+}, 'Duplicate name lookup order');
+
+</script>
+</body>
