feat: add vi.setConfig helper

docs/api/index.md

@@ -2598,6 +2598,12 @@ Vitest provides utility functions to help you out through it's **vi** helper. Yo
 
   Will call [`.mockReset()`](/api/#mockreset) on all spies. This will clear mock history and reset its implementation to an empty function (will return `undefined`).
 
+### vi.resetConfig
+
+- **Type**: `RuntimeConfig`
+
+  If [`vi.setConfig`](/api/#vi-setconfig) was called before, this will reset config to the original state.
+
 ### vi.resetModules
 
 - **Type**: `() => Vitest`
@@ -2691,6 +2697,12 @@ Vitest provides utility functions to help you out through it's **vi** helper. Yo
   vi.useRealTimers()
   ```
 
+### vi.setConfig
+
+- **Type**: `RuntimeConfig`
+
+  Updates config for the current test file. You can only affect values that are used, when executing tests.
+
 ### vi.spyOn
 
 - **Type:** `<T, K extends keyof T>(object: T, method: K, accessType?: 'get' | 'set') => MockInstance`

packages/vitest/src/integrations/vi.ts

@@ -1,6 +1,7 @@
 import type { FakeTimerInstallOpts } from '@sinonjs/fake-timers'
 import { parseStacktrace } from '../utils/source-map'
 import type { VitestMocker } from '../runtime/mocker'
+import type { ResolvedConfig, RuntimeConfig } from '../types'
 import { getWorkerState, resetModules, setTimeout } from '../utils'
 import { FakeTimers } from './mock/timers'
 import type { EnhancedSpy, MaybeMocked, MaybeMockedDeep, MaybePartiallyMocked, MaybePartiallyMockedDeep } from './spy'
@@ -260,6 +261,28 @@ class VitestUtils {
     // like in import('./example').then(...)
     await new Promise(resolve => setTimeout(resolve, 1)).then(() => Promise.resolve())
   }
+
+  private _config: null | ResolvedConfig = null
+
+  /**
+   * Updates runtime config. You can only change values that are used when executing tests.
+   */
+  public setConfig(config: RuntimeConfig) {
+    const state = getWorkerState()
+    if (!this._config)
+      this._config = { ...state.config }
+    Object.assign(state.config, config)
+  }
+
+  /**
+   * If config was changed with `vi.setConfig`, this will reset it to the original state.
+   */
+  public resetConfig() {
+    if (this._config) {
+      const state = getWorkerState()
+      state.config = { ...this._config }
+    }
+  }
 }
 
 export const vitest = new VitestUtils()

packages/vitest/src/runtime/entry.ts

@@ -1,6 +1,7 @@
 import { promises as fs } from 'fs'
 import type { EnvironmentOptions, ResolvedConfig, VitestEnvironment } from '../types'
 import { getWorkerState, resetModules } from '../utils'
+import { vi } from '../integrations/vi'
 import { envs } from '../integrations/env'
 import { setupGlobalEnv, withEnv } from './setup'
 import { startTests } from './run'
@@ -75,6 +76,9 @@ export async function run(files: string[], config: ResolvedConfig): Promise<void
           await startTests([file], config)
 
           workerState.filepath = undefined
+
+          // reset after tests, because user might call `vi.setConfig` in setupFile
+          vi.resetConfig()
         }
       })
     }

packages/vitest/src/types/config.ts

@@ -558,3 +558,15 @@ export interface ResolvedConfig extends Omit<Required<UserConfig>, 'config' | 'f
 
   typecheck: TypecheckConfig
 }
+
+export type RuntimeConfig = Pick<
+  UserConfig,
+  | 'allowOnly'
+  | 'testTimeout'
+  | 'hookTimeout'
+  | 'clearMocks'
+  | 'mockReset'
+  | 'restoreMocks'
+  | 'fakeTimers'
+  | 'maxConcurrency'
+>

test/core/test/vi.spec.ts

@@ -4,6 +4,7 @@
 
 import type { MockedFunction, MockedObject } from 'vitest'
 import { describe, expect, test, vi } from 'vitest'
+import { getWorkerState } from 'vitest/src/utils'
 
 const expectType = <T>(obj: T) => obj
 
@@ -64,6 +65,18 @@ describe('testing vi utils', () => {
     })
   })
 
+  test('can change config', () => {
+    const state = getWorkerState()
+    expect(state.config.hookTimeout).toBe(10000)
+    expect(state.config.clearMocks).toBe(false)
+    vi.setConfig({ hookTimeout: 6000, clearMocks: true })
+    expect(state.config.hookTimeout).toBe(6000)
+    expect(state.config.clearMocks).toBe(true)
+    vi.resetConfig()
+    expect(state.config.hookTimeout).toBe(10000)
+    expect(state.config.clearMocks).toBe(false)
+  })
+
   // TODO: it's unstable in CI, skip until resolved
   test.skip('loads unloaded module', async () => {
     let mod: any