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

test("length is 1", () => {
  expect(Reflect.isExtensible).toHaveLength(1);
});

describe("errors", () => {
  test("target must be an object", () => {
    [null, undefined, "foo", 123, NaN, Infinity].forEach(value => {
      expect(() => {
        Reflect.isExtensible(value);
      }).toThrowWithMessage(
        TypeError,
        "First argument of Reflect.isExtensible() must be an object"
      );
    });
  });
});

describe("normal behavior", () => {
  test("regular object is extensible", () => {
    expect(Reflect.isExtensible({})).toBeTrue();
  });

  test("global object is extensible", () => {
    expect(Reflect.isExtensible(globalThis)).toBeTrue();
  });

  test("regular object is not extensible after preventExtensions()", () => {
    var o = {};
    expect(Reflect.isExtensible(o)).toBeTrue();
    Reflect.preventExtensions(o);
    expect(Reflect.isExtensible(o)).toBeFalse();
  });
});