1 files changed, 29 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/history.window.js b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/history.window.js
new file mode 100644
index 0000000000..0134da24f0
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/history.window.js
@@ -0,0 +1,29 @@
+// Historically, document.open() created an entry in the session history so
+// that the original page could be seen by going back. Test that this behavior
+// no longer occurs.
+//
+// This test uses window.open() for variety, as most other tests in this
+// directory use document.open(). An <iframe> would probably work also. We can
+// always add an <iframe>-based test later if it is deemed necessary.
+
+const t = async_test("document.open should not add an entry to the session history");
+
+const frameURL = new URL("resources/history-frame.html", document.URL).href;
+
+let origLength;
+window.onFrameLoaded = t.step_func(() => {
+  window.onFrameLoaded = t.unreached_func("onFrameLoaded should only be called once");
+  assert_equals(win.document.URL, frameURL);
+  assert_true(win.document.body.textContent.includes("Old"));
+  origLength = win.history.length;
+});
+window.onDocumentOpen = t.step_func_done(() => {
+  window.onDocumentOpen = t.unreached_func("onDocumentOpen should only be called once");
+  assert_equals(win.document.URL, frameURL);
+  assert_true(win.document.body.textContent.includes("New"));
+  assert_not_equals(origLength, undefined);
+  assert_equals(win.history.length, origLength);
+});
+
+const win = window.open(frameURL);
+t.add_cleanup(() => win.close());