https://basarat.gitbook.io/typescript/intro-1/jest Following is wrong: ``` test('basic',async () => { expect(sum()).toBe(0); }); test('basic again', async () => { expect(sum(1, 2)).toBe(3); }, 1000 /* optional timeout */); ``` You need await like: ``` test('basic', async () => { expect(await sum()).toBe(0); }); ```