Jest react testing: Check state after delay

while jest can run async code easily, you can use promise and setTimeout combination to wait a bit. For example this code will wait for 2 seconds:

await new Promise((r) => setTimeout(r, 2000));

Full sample test. Don’t forget to add async flag before the callback function:

test('some test title', async () => {
  const foo = true;
  await new Promise((r) => setTimeout(r, 2000));
  expect(foo).toBeDefined();
});

Also, keep in mind that default “timeout” is 5 seconds (5000ms). If your test may run longer, you can add jest.setTimeout(30000); above the test(). 30000 will make sure to not timeout for 30 seconds. You can add any number you need. Full example with setTimeout:

jest.setTimeout(30000);

test('some test title', async () => {
  const foo = true;
  await new Promise((r) => setTimeout(r, 2000));
  expect(foo).toBeDefined();
});