diff --git a/dom/tests/browser/browser.ini b/dom/tests/browser/browser.ini
index 350fcb660a89..e385333d2898 100644
--- a/dom/tests/browser/browser.ini
+++ b/dom/tests/browser/browser.ini
@@ -48,6 +48,7 @@ skip-if = e10s
[browser_ConsoleStorageAPITests.js]
skip-if = fission || (asan && os == "linux") # Bug 1614436
[browser_ConsoleStoragePBTest_perwindowpb.js]
+[browser_data_document_crossOriginIsolated.js]
[browser_focus_steal_from_chrome.js]
[browser_focus_steal_from_chrome_during_mousedown.js]
[browser_frame_elements.js]
diff --git a/dom/tests/browser/browser_data_document_crossOriginIsolated.js b/dom/tests/browser/browser_data_document_crossOriginIsolated.js
new file mode 100644
index 000000000000..ccac56cb31c0
--- /dev/null
+++ b/dom/tests/browser/browser_data_document_crossOriginIsolated.js
@@ -0,0 +1,68 @@
+"use strict";
+
+const DIRPATH = getRootDirectory(gTestPath).replace(
+ "chrome://mochitests/content/",
+ ""
+);
+const PATH = DIRPATH + "file_coop_coep.html";
+
+const ORIGIN = "https://test1.example.com";
+const URL = `${ORIGIN}/${PATH}`;
+
+add_task(async function() {
+ await BrowserTestUtils.withNewTab(URL, async function(browser) {
+ BrowserTestUtils.loadURI(browser, URL);
+ await BrowserTestUtils.browserLoaded(browser);
+
+ await SpecialPowers.spawn(browser, [ORIGIN], async origin => {
+ is(
+ content.window.origin,
+ origin,
+ `Opened a tab and navigated to ${origin}`
+ );
+
+ ok(
+ content.window.crossOriginIsolated,
+ `Should have been cross-origin-isolated env`
+ );
+
+ let hostIds = [];
+ function createShadowDOMAndTriggerSlotChange(host) {
+ var shadow = host.attachShadow({ mode: "closed" });
+
+ let promise = new Promise(resolve => {
+ shadow.addEventListener("slotchange", function() {
+ hostIds.push(host.id);
+ resolve();
+ });
+ });
+
+ shadow.innerHTML = "";
+
+ host.appendChild(host.ownerDocument.createElement("span"));
+
+ return promise;
+ }
+
+ let host1 = content.document.getElementById("host1");
+
+ let dataDoc = content.document.implementation.createHTMLDocument();
+ dataDoc.body.innerHTML = "";
+ let host2 = dataDoc.body.firstChild;
+
+ let host3 = content.document.getElementById("host3");
+
+ let promises = [];
+ promises.push(createShadowDOMAndTriggerSlotChange(host1));
+ promises.push(createShadowDOMAndTriggerSlotChange(host2));
+ promises.push(createShadowDOMAndTriggerSlotChange(host3));
+
+ await Promise.all(promises);
+
+ is(hostIds.length, 3, `Got 3 slot change events`);
+ is(hostIds[0], "host1", `The first one was host1`);
+ is(hostIds[1], "host2", `The second one was host2`);
+ is(hostIds[2], "host3", `The third one was host3`);
+ });
+ });
+});
diff --git a/dom/tests/browser/file_coop_coep.html b/dom/tests/browser/file_coop_coep.html
index e69de29bb2d1..f77ef9d5f276 100644
--- a/dom/tests/browser/file_coop_coep.html
+++ b/dom/tests/browser/file_coop_coep.html
@@ -0,0 +1,6 @@
+
+
+
+
+
+