ladybird/Libraries/LibJS/Tests/builtins/Object/Object.isExtensible.js

test("basic functionality", () => {
  expect(Object.isExtensible).toHaveLength(1);

  expect(Object.isExtensible()).toBeFalse();
  expect(Object.isExtensible(undefined)).toBeFalse();
  expect(Object.isExtensible(null)).toBeFalse();
  expect(Object.isExtensible(true)).toBeFalse();
  expect(Object.isExtensible(6)).toBeFalse();
  expect(Object.isExtensible("test")).toBeFalse();

  let s = Symbol();
  expect(Object.isExtensible(s)).toBeFalse();

  let o = { foo: "foo" };
  expect(Object.isExtensible(o)).toBeTrue();
  Object.preventExtensions(o);
  expect(Object.isExtensible(o)).toBeFalse();
});