test("inside objects", () => { const o = { [Symbol.toStringTag]: "hello friends", }; expect(o.toString()).toBe("[object hello friends]"); }); test("inside classes", () => { class A { constructor() { this[Symbol.toStringTag] = "hello friends"; } } const a = new A(); expect(a.toString()).toBe("[object hello friends]"); }); test("non-string values are ignored", () => { const o = { [Symbol.toStringTag]: [1, 2, 3], }; expect(o.toString()).toBe("[object Object]"); });