[Vitest - RTK Query - MSW] Store not updating in specific case after upgrade to RTK v2 and react-redux v9

[followynne]

Hello everyone,

in our project we use Vitest as the test runner and MSW to mock endpoint calls.

Issue

When I upgrade react-redux: 8.1.3 => 9.0.4 and RTK: 1.9.7 => 2.0.1, some tests start to fail.

We have a selector that access an RTK Query in the following way:

const selectUserResult = userApi.endpoints.getUser.select();

export const selectUser = createSelector(
  selectUserResult,
  (userResult) =>
    userResult.data ?? { Id: "", Email: "", Permissions: [] as Array<string> },
);

In the real application we call the getUser endpoint before rendering the React application and it works fine when we upgrade the versions.

During testing we execute the api call manually and mock it out with MSW; with the v8/v1 versions the selector updates correctly while, on the latter versions, the selector doesn't change after the first render.

Steps to reproduce

I created this CodeSandbox sample with the minimum amount of code to reproduce the issue.

If you run the test terminal with the sandbox as-it-is, you'll see the successful tests; if you upgrade the versions the tests will fail (you'll see in the logging the different behavior).

Additional info

If it's not a bug, can you kindly point us to a different approach to get the API results in a selector function?

Thanks for the help 🤗

[markerikson]

Thanks for filing and the repro! I'll try to look at it when I get a chance, but I'm on travel and it may be a while.

[followynne]

No worries, thanks for checking in already! We're not in an hurry to update and can wait when you have some free time 😁

[EskiMojo14]

for what it's worth, if you add enhancers: (getDefaultEnhancers) => getDefaultEnhancers({ autoBatch: false }) to your store setup, the tests pass again.

The autoBatchEnhancer is added to the store by default in RTK 2.0, and your test seems to function in such a way that it doesn't account for this batching of subscribers.

[phryneas]

So probably adding another await Promise.resolve() before making the assertions might already make it pass without disabling the autoBatching behaviour (which you should probably keep on).

[followynne]

@EskiMojo14 @phryneas

thanks a lot for the answer!
I gave a try to both suggestions and I can confirm that

• the entire test suite would succeed by disabling the autoBatch
• adding a Promise.resolve doesn't work, I tried on some tests but it's not enough [I tried by inserting it in different places, 1) in the act callback 2) just before the assertions]

[phryneas]

Could also need a small timeout or something - usually when writing tests for React, you'd use findBy... type queries or the waitFor helper to wait until the DOM changed accordingly, so it's not important to be accurate to a scpecific ping.