1 files changed, 17 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/browsers/the-window-object/window-opener-unconfigurable.window.js b/testing/web-platform/tests/html/browsers/the-window-object/window-opener-unconfigurable.window.js
new file mode 100644
index 0000000000..2b9bda6792
--- /dev/null
+++ b/testing/web-platform/tests/html/browsers/the-window-object/window-opener-unconfigurable.window.js
@@ -0,0 +1,17 @@
+test(t => {
+  let desc = Object.getOwnPropertyDescriptor(self, "opener");
+  assert_true(!!desc.get, "Initially {get: function}");
+  assert_true(!!desc.set, "Initially {set: function}");
+  assert_true(desc.configurable, "Initially {configurable: true}");
+  assert_true(desc.enumerable, "Initially {enumerable: true}");
+
+  Object.defineProperty(self, "opener", {configurable: false});
+
+  desc = Object.getOwnPropertyDescriptor(self, "opener");
+  assert_true(!!desc.get, "Still has {get: function}");
+  assert_true(!!desc.set, "Still has {set: function}");
+  assert_false(desc.configurable, "Changed to {configurable: false}");
+  assert_true(desc.enumerable, "Still has {enumerable: true}");
+
+  assert_throws_js(TypeError, () => self.opener = "something", "Throws a TypeError due to {configurable: false}");
+}, "Corner case: self.opener is set while it's not configurable");