Can't test timer in react using vitest (jest)-CodePudding

I have this simple component in react and I want to test it but I cannot find a way to mock the setInterval in order to trigger the timer.
The count value is 0 all the time but when I run the component it's working.

UPDATE: I've added this sample respository on stackblitz for running this test.
This is my test file:

import {
  render,
  screen
} from "@testing-library/react";
import React, { useEffect, useState } from "react";
import { expect, test, vi } from "vitest";

function Timer() {
  const [count, setCount] = useState(0)
  useEffect(() => {
    let timer = setInterval(() => {
      setCount(v => v   1)
    }, 1000)
    return () => clearInterval(timer)
  }, [])
  return <div>{count}</div>
}
test("should render correctly", () => {
    vi.useFakeTimers();
    render(<Timer />);
    vi.advanceTimersByTime(2000);
    screen.debug();
    expect(screen.getByText("2")).toBeDefined();
});

CodePudding user response：

The problem was with vitest not being able to notice the dom changes made during the test. The dom update code should be wrapped within an act method from react-dom/test-utils.

So vi.advanceTimersByTime(2000); must be in act.

Theis is the link to the guthub issue I opened for this problem