Usage with @aws-amplify next/SSR

Hi there,

🚀 Feature Proposal

While using withSSRContext from @aws-amplify (https://github.com/aws-amplify/amplify-js) in getServerSideProps we get ReferenceError: window is not defined

Should we mock getServerSideProps ?

[toomuchdesign]

A fix is available in #73 which is blocked until Jest v27 gets released.

[Meemaw]

I looked into this and its caused by a very annoying issue we are facing in this library: external modules eagerly evaluating document | window existence on top level (on import). This happens before next-page-tester is in “control” of things and could “wire” it correctly.

@toomuchdesign:

@aws-amplify first checks if its browser environment upon import and that evaluates to true because of JSDOM, and then tries to access localStorage in getServerSideProps which is not available.

I expect this will cause problems with many external libraries and we probably need to find some solution for this. I though about just deleting window and document in our initTestHelpers and then restoring them in getPage which would help in this example, but will break other libraries, e.g. react-hook-form which then won’t work correctly because it will assume its not in JSDOM.

This is not a problem for NextJS where code is executed in 2 different environments (Node + Browser). I think in our case we need to find a reliable way to wipe require.cache after initial “SSR” render and then let JSDOM take over. Unfortunately I don’t know if there is a reliable way to do this since test frameworks are using hacks to “re-implement” require mechanism.

If there is not a reliable cross-framework way we could consider implementing framework specific ones like this:

import { initTestHelpers } from 'next-page-tester/jest'

☝️ in there we could call jest.resetModules() which wipes the cache.