feat: add vi.resetModules (#1102)

docs/api/index.md

@@ -1483,6 +1483,31 @@ Vitest provides utility functions to help you out through it's **vi** helper. Yo
 
   Imports a module with all of its properties (including nested properties) mocked. Follows the same rules that [`vi.mock`](#vi-mock) follows. For the rules applied, see [algorithm](/guide/mocking#automocking-algorithm).
 
+### vi.resetModules
+
+- **Type**: `() => Vitest`
+
+  Resets modules registry by clearing cache of all modules. Might be useful to isolate modules where local state conflicts between tests.
+
+  ```ts
+  import { vi } from 'vitest'
+
+  beforeAll(() => {
+    vi.resetModules()
+  })
+
+  test('change state', async() => {
+    const mod = await import('./some/path')
+    mod.changeLocalState('new value')
+    expect(mod.getlocalState()).toBe('new value')
+  })
+
+  test('module has old state', async() => {
+    const mod = await import('./some/path')
+    expect(mod.getlocalState()).toBe('old value')
+  })
+  ```
+
 ### vi.restoreCurrentDate
 
 - **Type**: `() => void`

packages/vitest/src/integrations/vi.ts

@@ -2,6 +2,7 @@
 
 import { parseStacktrace } from '../utils/source-map'
 import type { VitestMocker } from '../runtime/mocker'
+import { resetModules } from '../utils'
 import { FakeTimers } from './timers'
 import type { EnhancedSpy, MaybeMocked, MaybeMockedDeep } from './spy'
 import { fn, isMockFunction, spies, spyOn } from './spy'
@@ -210,6 +211,11 @@ class VitestUtils {
 
     return this
   }
+
+  public resetModules() {
+    resetModules()
+    return this
+  }
 }
 
 export const vitest = new VitestUtils()

packages/vitest/src/runtime/entry.ts

@@ -1,6 +1,6 @@
 import { promises as fs } from 'fs'
 import type { BuiltinEnvironment, ResolvedConfig } from '../types'
-import { getWorkerState } from '../utils'
+import { getWorkerState, resetModules } from '../utils'
 import { setupGlobalEnv, withEnv } from './setup'
 import { startTests } from './run'
 
@@ -9,10 +9,10 @@ export async function run(files: string[], config: ResolvedConfig): Promise<void
 
   const workerState = getWorkerState()
 
-  // reset mock state
-  workerState.mockMap.clear()
-
   for (const file of files) {
+    workerState.mockMap.clear()
+    resetModules()
+
     const code = await fs.readFile(file, 'utf-8')
 
     const env = code.match(/@(?:vitest|jest)-environment\s+?([\w-]+)\b/)?.[1] || config.environment || 'node'

packages/vitest/src/utils/index.ts

@@ -2,6 +2,7 @@ import c from 'picocolors'
 import { isPackageExists } from 'local-pkg'
 import { resolve } from 'pathe'
 import type { Suite, Task } from '../types'
+import { getWorkerState } from '../utils/global'
 import { getNames } from './tasks'
 
 export * from './tasks'
@@ -32,6 +33,23 @@ export function partitionSuiteChildren(suite: Suite) {
   return tasksGroups
 }
 
+export function resetModules() {
+  const modules = getWorkerState().moduleCache
+  const vitestPaths = [
+    // Vitest
+    /\/vitest\/dist\//,
+    // yarn's .store folder
+    /vitest-virtual-\w+\/dist/,
+    // cnpm
+    /@vitest\/dist/,
+  ]
+  modules.forEach((_, path) => {
+    if (vitestPaths.some(re => re.test(path)))
+      return
+    modules.delete(path)
+  })
+}
+
 export function getFullName(task: Task) {
   return getNames(task).join(c.dim(' > '))
 }

test/core/test/vi.spec.ts

@@ -12,4 +12,20 @@ describe('testing vi utils', () => {
     expect(window.IntersectionObserver).toBe(IntersectionObserverMock)
     expect(IntersectionObserver).toBe(IntersectionObserverMock)
   })
+
+  test('reseting modules', async() => {
+    const mod1 = await import('../src/env')
+    vi.resetModules()
+    const mod2 = await import('../src/env')
+    const mod3 = await import('../src/env')
+    expect(mod1).not.toBe(mod2)
+    expect(mod2).toBe(mod3)
+  })
+
+  test('reseting modules doesnt reset vitest', async() => {
+    const v1 = await import('vitest')
+    vi.resetModules()
+    const v2 = await import('vitest')
+    expect(v1).toBe(v2)
+  })
 })