1 files changed, 58 insertions, 0 deletions
diff --git a/js/xpconnect/tests/unit/test_private_field_xrays.js b/js/xpconnect/tests/unit/test_private_field_xrays.js
new file mode 100644
index 0000000000..bd37eb44c7
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_private_field_xrays.js
@@ -0,0 +1,58 @@
+'use strict'
+
+ChromeUtils.importESModule("resource://gre/modules/Preferences.sys.mjs");
+
+add_task(async function () {
+  let webnav = Services.appShell.createWindowlessBrowser(false);
+
+  let docShell = webnav.docShell;
+
+  docShell.createAboutBlankContentViewer(null, null);
+
+  let window = webnav.document.defaultView;
+
+  let iframe = window.eval(`
+    iframe = document.createElement("iframe");
+    iframe.id = "iframe"
+    document.body.appendChild(iframe)
+    iframe`);
+
+
+  let unwrapped = Cu.waiveXrays(iframe);
+
+
+  class Base {
+    constructor(o) {
+      return o;
+    }
+  };
+
+
+  class A extends Base {
+    #x = 12;
+    static gx(o) {
+      return o.#x;
+    }
+
+    static sx(o, v) {
+      o.#x = v;
+    }
+  };
+
+  new A(iframe);
+  Assert.equal(A.gx(iframe), 12);
+  A.sx(iframe, 'wrapped');
+
+  // Shouldn't tunnel past xray.
+  Assert.throws(() => A.gx(unwrapped), TypeError);
+  Assert.throws(() => A.sx(unwrapped, 'unwrapped'), TypeError);
+
+  new A(unwrapped);
+  Assert.equal(A.gx(unwrapped), 12);
+  Assert.equal(A.gx(iframe), 'wrapped');
+
+  A.sx(iframe, 'modified');
+  Assert.equal(A.gx(unwrapped), 12);
+  A.sx(unwrapped, 16);
+  Assert.equal(A.gx(iframe), 'modified');
+});