vi.mock ignored if module is imported in setup file

[MaartenPetiet]

Describe the bug

Registration of vi.mock on a module will not work if that module is imported in a file added to the setupFiles array in vite.config.ts.

Use case

We use Vue 3 with global component registration (this is needed because of the way our CMS works). To accomplish this in our tests, we register these components in vitest.setup.ts to the @vue/test-utils config as the example below.

import { config } from '@vue/test-utils';

config.global.components[name] = component;

This causes the mocks set on the imports of these components to be ignored. Although this is our use case, this issue is unrelated to Vue. See the minimal reproduction for more details.

Reproduction

Here is a minimal repo: https://stackblitz.com/edit/vitest-dev-vitest-etmse4?file=vitest.setup.ts

In test/foo.test.ts a mock is used. This fails, unless I remove the only line in vitest.setup.ts.

System Info

System:
    OS: Windows 10 10.0.17763
    CPU: (4) x64 Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
    Memory: 4.85 GB / 16.00 GB
  Binaries:
    Node: 14.17.6 - C:\Program Files\nodejs\node.EXE
    npm: 6.14.15 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 102.0.5005.63
    Internet Explorer: 11.0.17763.2145
  npmPackages:
    @vitejs/plugin-vue: ^2.3.3 => 2.3.3
    vite: ^2.9.9 => 2.9.9
    vitest: 0.14.1 => 0.14.1

Used Package Manager

npm

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[sheremet-va]

I found the problem, but I am not sure it's possible to fix without losing performance.

For now, you can call vi.resetModules() before any imports in a test file.

[MaartenPetiet]

Thanks, I have added vi.resetModules() at the end of vitest.setup.ts to only call it once and that seems to work too.

[sheremet-va]

Module was already evaluated and cached with code that you provided in setup, so when it is imported next time, it uses this cached version. I don't think there is a good way for us to clear that cache automatically, so you need to use vi.resetModules.