Intermittent test failures when upgrading from 3.3 to 3.4.16

I recently updated a project from version 3.3 to 3.4.16 and I’m now seeing intermittent errors in my tests. The tests are using React and @testing-library/react with jest. The main issue is that tests occasionally get stuck in the “Loading” state. In the documentation, https://www.apollographql.com/docs/react/development-testing/testing/#testing-the-success-state, states that all I should need to do is await a 0ms timeout, but that’s already being done. Is this a bug with @apollo/client or am I doing something wrong here?

An example of a test that is failing randomly.

test("renders control view when data exists", async () => {
  await act(async () => {
    renderControlViewForMockId(CONTROL_WITH_TESTS_AND_RELATED_CTRLS);
    await new Promise((resolve) => setTimeout(resolve, 0));
  });

  const text = screen.getAllByText("Control 1");
  expect(text.length).toBe(2);
  expect(text[0]).toBeInTheDocument();
  expect(text[1]).toBeInTheDocument();
});

The render method.

const renderControlViewForMockId = (id: string) => {
  render(
    <MockedProvider mocks={[...queryMocks, ...eventMocks]} addTypename={false}>
      <MemoryRouter initialEntries={[`/testUrl/${id}`]}>
        <Route path="/base/:baseId/sub/:subId">
          <ModalProvider>
            <ModalWrapper>
              <ControlContainer />
            </ModalWrapper>
          </ModalProvider>
        </Route>
      </MemoryRouter>
    </MockedProvider>
  );
};

[bignimbus]

Hi all, I’ll close this issue for now since it appears to have been resolved in newer releases. Please let us know if you need more support here 🙏🏻

[brainkim]

There is a findAllByText() method which seems to wrap getAllBy() call in an act so that it is awaitable (https://testing-library.com/docs/dom-testing-library/cheatsheet/#queries). I think that might help your use-case?

seems like it is covering up a symptom rather than the cause. This issue only happens when updating our apollo client version. I don’t know how to reliably reproduce this since the errors are not consistent and it seems to be an issue with the timing during the test.

I appreciate the concern, but I believe your issues are with React, not Apollo Client. We don’t consider the exact timings of the hooks to be part of the public interface, and APIs like useEffect() and useState() are not guaranteed to run synchronously, even if that’s how they work today. The hooks are being heavily refactored, and the timings will change between minor versions. The fact that react-testing-library has to implement all these polling methods is more or less an admission of this lack of precision on React’s part.

I would try awaiting a screen.findAllByText() call and seeing if that helps with the flake!