Vitest #99

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1. sheremet-va commented on Jul 18, 2022

   

   sheremet-va

   on Jul 18, 2022

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   Hello! I think one of the problems we will encounter, if we were to use esm, is mocking Module methods. As far as I know spec doesn't allow rewriting exported module variables?
2. sheremet-va commented on Jul 19, 2022

   

   sheremet-va

   on Jul 19, 2022

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   To fix some of the described problems we are thinking to add a loader that will only process aliasing inside node_modules, and to use our own module resolution for source files (to support jest-style module mocking, for example).

   • I found that we can actually define --conditions when firing up a worker, so it is not an issue. Apologies.
   • We have a single server instance in the main thread that is processing all requests, we do not want to create a new server for each loader. I see that you are planning to move loaders off thread - will there be a way or is there a way loader can communicate with the main thread? For reference: fix: apply Vite resolving algorithm to node_modules libraries vitest-dev/vitest#1673
3. JakobJingleheimer commented on Jul 19, 2022

   

   JakobJingleheimer

   on Jul 19, 2022

   Last edited by JakobJingleheimer

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   Hello! I think one of the problems we will encounter, if we were to use esm, is mocking Module methods. As far as I know spec doesn't allow rewriting exported module variables?

   It is possible with a loader. See https://dev.to/jakobjingleheimer/custom-esm-loaders-who-what-when-where-why-how-4i1o#all-together-now

   I see that you are planning to move loaders off thread - will there be a way or is there a way loader can communicate with the main thread?

   Yes, there is a test in node that does this via the globalPreload hook: nodejs/node#39240
4. sheremet-va commented on Jul 19, 2022

   

   sheremet-va

   on Jul 19, 2022

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   It is possible with a loader

   I don't see how it's possible with provided link? It's not possible to redefine property on Module object. This is how spying works, no? Compiling it to CJS will work, off, but I was thinking we are doing ESM here 😄

   Yes, there is a test in node that does this via the globalPreload hook.

   Can you point me to that? Our idea is:

   • Run script that fires up a Vite server and after that a worker with custom --loader
   • Inside resolve hook loader asks from Vite server how to resolve path

   I am struggling with the second one. We have a server in another thread, but I don't see how I can pass down a connection to the loader itself.
5. JakobJingleheimer commented on Jul 19, 2022

   

   JakobJingleheimer

   on Jul 19, 2022

   Last edited by JakobJingleheimer

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   It is possible with a loader

   I don't see how it's possible with provided link? It's not possible to redefine property on Module object.

   Ah, I think maybe I misunderstood. For that, you'd need to use a dynamic import in your test file before importing the implementation:

   const Module_mocked = await import('node:module')
     .then((original) => {
       // do whatever
       return {
         // your mock here
       };
     });
   const implementationToBeTested = await import('./whatever.mjs')
     .then((module) => module.default);

   Yes, there is a test in node that does this via the globalPreload hook.

   Can you point me to that?

   @sheremet-va yes, I just added it to my message as you posted yours 😅