Jest react testing: Check state after delay
I haven't really tested this code. But, something similar to this should work I think.
const fruits = ['banana', 'apple', 'orange', 'vodka', 'kiwi'];
it('mock setTimeout test', () => {
jest.useFakeTimers();
setTimeout(() => {
expect(component.state().fruits).toEqual(fruits);
}, 1500);
jest.runAllTimers();
});
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();
});