1 files changed, 34 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webidl/ecmascript-binding/observable-array-ownkeys.window.js b/testing/web-platform/tests/webidl/ecmascript-binding/observable-array-ownkeys.window.js
new file mode 100644
index 0000000000..29b537c475
--- /dev/null
+++ b/testing/web-platform/tests/webidl/ecmascript-binding/observable-array-ownkeys.window.js
@@ -0,0 +1,34 @@
+"use strict";
+
+test(() => {
+  const observableArray = document.adoptedStyleSheets;
+  assert_array_equals(
+      Object.getOwnPropertyNames(observableArray),
+      ["length"],
+      "Initially only \"length\".");
+
+  observableArray["zzz"] = true;
+  observableArray["aaa"] = true;
+  assert_array_equals(
+      Object.getOwnPropertyNames(observableArray),
+      ["length", "zzz", "aaa"],
+      "Own properties whose key is a string have been added.");
+
+  observableArray[0] = new CSSStyleSheet();
+  observableArray[1] = new CSSStyleSheet();
+  assert_array_equals(
+      Object.getOwnPropertyNames(observableArray),
+      ["0", "1", "length", "zzz", "aaa"],
+      "Own properties whose key is an array index have been added.");
+
+  observableArray[Symbol.toStringTag] = "string_tag";
+  observableArray[Symbol.toPrimitive] = "primitive";
+  assert_array_equals(
+      Object.getOwnPropertyNames(observableArray),
+      ["0", "1", "length", "zzz", "aaa"],
+      "Own properties whose key is a symbol have been added (non-symbol).");
+  assert_array_equals(
+      Object.getOwnPropertySymbols(observableArray),
+      [Symbol.toStringTag, Symbol.toPrimitive],
+      "Own properties whose key is a symbol have been added (symbol).");
+}, "ObservableArray's ownKeys trap");