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feat(vitest): add return type and promisable mockFactory (#6139)
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Co-authored-by: Vladimir Sheremet <sleuths.slews0s@icloud.com>
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syi0808 and sheremet-va authored Aug 12, 2024
1 parent 5932a7f commit f5e0b98
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8 changes: 5 additions & 3 deletions docs/api/vi.md
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Expand Up @@ -17,7 +17,7 @@ This section describes the API that you can use when [mocking a module](/guide/m
### vi.mock

- **Type**: `(path: string, factory?: (importOriginal: () => unknown) => unknown) => void`
- **Type**: `<T>(path: Promise<T>, factory?: (importOriginal: () => T) => unknown) => void`
- **Type**: `<T>(path: Promise<T>, factory?: (importOriginal: () => T) => T | Promise<T>) => void`

Substitutes all imported modules from provided `path` with another module. You can use configured Vite aliases inside a path. The call to `vi.mock` is hoisted, so it doesn't matter where you call it. It will always be executed before all imports. If you need to reference some variables outside of its scope, you can define them inside [`vi.hoisted`](#vi-hoisted) and reference them inside `vi.mock`.

Expand All @@ -31,7 +31,9 @@ Vitest will not mock modules that were imported inside a [setup file](/config/#s

If `factory` is defined, all imports will return its result. Vitest calls factory only once and caches results for all subsequent imports until [`vi.unmock`](#vi-unmock) or [`vi.doUnmock`](#vi-dounmock) is called.

Unlike in `jest`, the factory can be asynchronous. You can use [`vi.importActual`](#vi-importactual) or a helper with the factory passed in as the first argument, and get the original module inside. Vitest also supports a module promise instead of a string in `vi.mock` method for better IDE support (when file is moved, path will be updated, `importOriginal` also inherits the type automatically).
Unlike in `jest`, the factory can be asynchronous. You can use [`vi.importActual`](#vi-importactual) or a helper with the factory passed in as the first argument, and get the original module inside.

Vitest also supports a module promise instead of a string in the `vi.mock` and `vi.doMock` methods for better IDE support. When the file is moved, the path will be updated, and `importOriginal` also inherits the type automatically. Using this signature will also enforce factory return type to be compatible with the original module (but every export is optional).

```ts twoslash
// @filename: ./path/to/module.js
Expand Down Expand Up @@ -143,7 +145,7 @@ If there is no `__mocks__` folder or a factory provided, Vitest will import the
### vi.doMock

- **Type**: `(path: string, factory?: (importOriginal: () => unknown) => unknown) => void`
- **Type**: `<T>(path: Promise<T>, factory?: (importOriginal: () => T) => unknown) => void`
- **Type**: `<T>(path: Promise<T>, factory?: (importOriginal: () => T) => T | Promise<T>) => void`

The same as [`vi.mock`](#vi-mock), but it's not hoisted to the top of the file, so you can reference variables in the global file scope. The next [dynamic import](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import) of the module will be mocked.

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6 changes: 4 additions & 2 deletions packages/vitest/src/types/mocker.ts
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@@ -1,6 +1,8 @@
type Promisable<T> = T | Promise<T>

export type MockFactoryWithHelper<M = unknown> = (
importOriginal: <T extends M>() => Promise<T>
) => any
importOriginal: <T extends M = M>() => Promise<T>
) => Promisable<Partial<M>>
export type MockFactory = () => any

export type MockMap = Map<string, Record<string, string | null | MockFactory>>
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1 change: 1 addition & 0 deletions test/config/test/workers-option.test.ts
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Expand Up @@ -4,6 +4,7 @@ import { getWorkersCountByPercentage } from 'vitest/src/utils/workers.js'
import * as testUtils from '../../test-utils'

vi.mock(import('node:os'), async importOriginal => ({
...(await importOriginal()),
default: {
...(await importOriginal()).default,
availableParallelism: () => 10,
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2 changes: 1 addition & 1 deletion test/core/test/mocking/factory.test.ts
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Expand Up @@ -54,7 +54,7 @@ vi.mock('../../src/mocks/log.ts', async () => {
},
}
})

// @ts-expect-error null is not allowed to mocked implementation
vi.mock('../../src/mocks/default.ts', () => null)

describe('mocking with factory', () => {
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