class Foo {
  static #foo = "foo";
  #bar = "bar";

  static test() {
    return Foo.#foo;
  }

  test() {
    return this.#bar;
  }
}

const f = new Foo();
expect("foo" in Foo).toBe(false)
expect("bar" in f).toBe(false)
expect(Foo.test()).toBe("foo")
expect(f.test()).toBe("bar")