Nicolas Terray

Sorry I forgot to mention that it was to be able to mock getters in tests https://pinia.vuejs.org/cookbook/testing.html#mocking-getters

By the way TypeScript complains about this error for [Pinia's test file](https://github.com/vuejs/pinia/blob/pinia%402.0.21/packages/testing/src/testing.spec.ts) : ``` ➜ ./node_modules/.bin/tsc packages/testing/src/testing.spec.ts […] packages/testing/src/testing.spec.ts:217:11 - error TS2540: Cannot assign to 'double' because it is a...