type: vi.spyOn(window.localStorage, 'getItem') inferred as never

[cexbrayat]

Describe the bug

vi.spyOn(window.localStorage, 'getItem') is wrongly inferred as never isntead of SpyInstance.

tests/composables/UserService.spec.ts:58:44 - error TS2339: Property 'mockReturnValue' does not exist on type 'never'.

58     vi.spyOn(window.localStorage, 'getItem').mockReturnValue(null));

Reproduction

This can be seen in the TS playground here

import { vi, SpyInstance } from 'vitest'

// does not compile when spying on Storage (spy inferred as never)
vi.spyOn(window.localStorage, 'getItem').mockReturnValue(null);
vi.spyOn(Storage.prototype, 'getItem').mockReturnValue(null);

// whereas it properly compiles on an object
const storage = {
    getItem(key: string): string | null { return null }
}
vi.spyOn(storage, 'getItem').mockReturnValue(null);

// workaround: explicit cast
(vi.spyOn(Storage.prototype, 'getItem') as SpyInstance<Array<string>, string | null>).mockReturnValue(null);

System Info

System:
    OS: macOS 12.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 15.84 GB / 64.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.13.2 - ~/.volta/tools/image/node/16.13.2/bin/node
    Yarn: 1.22.17 - ~/.volta/tools/image/yarn/1.22.17/bin/yarn
    npm: 8.3.2 - ~/.volta/tools/image/npm/8.3.2/bin/npm
  Browsers:
    Chrome: 97.0.4692.99
    Firefox: 96.0.2
    Safari: 15.2
  npmPackages:
    @vitejs/plugin-vue: 2.0.1 => 2.0.1
    vite: 2.7.13 => 2.7.13
    vitest: 0.2.3 => 0.2.3

Used Package Manager

npm

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