feat: allow reassigning define globals

packages/vitest/src/node/plugins/index.ts

@@ -1,12 +1,11 @@
 import type { Plugin as VitePlugin } from 'vite'
 import { configDefaults } from '../../defaults'
-import type { UserConfig } from '../../types'
+import type { ResolvedConfig, UserConfig } from '../../types'
 import { deepMerge, ensurePackageInstalled, notNullish } from '../../utils'
 import { resolveApiConfig } from '../config'
 import { Vitest } from '../core'
 import { GlobalSetupPlugin } from './globalSetup'
 import { MocksPlugin } from './mock'
-import { EnvReplacerPlugin } from './envReplacer'
 
 export async function VitestPlugin(options: UserConfig = {}, ctx = new Vitest()): Promise<VitePlugin[]> {
   let haveStarted = false
@@ -27,6 +26,39 @@ export async function VitestPlugin(options: UserConfig = {}, ctx = new Vitest())
         const preOptions = deepMerge({}, options, viteConfig.test ?? {})
         preOptions.api = resolveApiConfig(preOptions)
 
+        // store defines for globalThis to make them
+        // reassignable when running in worker in src/runtime/setup.ts
+        const defines: Record<string, any> = {}
+
+        for (const key in viteConfig.define) {
+          const val = viteConfig.define[key]
+          let replacement: any
+          try {
+            replacement = typeof val === 'string' ? JSON.parse(val) : val
+          }
+          catch {
+            // probably means it contains reference to some variable,
+            // like this: "__VAR__": "process.env.VAR"
+            continue
+          }
+          if (key.startsWith('import.meta.env.')) {
+            const envKey = key.slice('import.meta.env.'.length)
+            process.env[envKey] = replacement
+            delete viteConfig.define[key]
+          }
+          else if (key.startsWith('process.env.')) {
+            const envKey = key.slice('process.env.'.length)
+            process.env[envKey] = replacement
+            delete viteConfig.define[key]
+          }
+          else if (!key.includes('.')) {
+            defines[key] = replacement
+            delete viteConfig.define[key]
+          }
+        }
+
+        (options as ResolvedConfig).defines = defines
+
         return {
           // we are setting NODE_ENV when running CLI to 'test',
           // but it can be overridden
@@ -37,6 +69,14 @@ export async function VitestPlugin(options: UserConfig = {}, ctx = new Vitest())
             // setting this option can bypass that and fallback to cjs version
             mainFields: [],
           },
+          define: {
+            'process.env.NODE_ENV': 'process.env.NODE_ENV',
+            'global.process.env.NODE_ENV': 'global.process.env.NODE_ENV',
+            'globalThis.process.env.NODE_ENV': 'globalThis.process.env.NODE_ENV',
+            // so people can reassign envs at runtime
+            // import.meta.env.VITE_NAME = 'app' -> process.env.VITE_NAME = 'app'
+            'import.meta.env': 'process.env',
+          },
           server: {
             ...preOptions.api,
             open: preOptions.ui && preOptions.open
@@ -74,15 +114,6 @@ export async function VitestPlugin(options: UserConfig = {}, ctx = new Vitest())
 
         for (const name in envs)
           process.env[name] ??= envs[name]
-
-        // account for user env defines
-        for (const key in viteConfig.define) {
-          if (key.startsWith('import.meta.env.')) {
-            const val = viteConfig.define[key]
-            const envKey = key.slice('import.meta.env.'.length)
-            process.env[envKey] = typeof val === 'string' ? JSON.parse(val) : val
-          }
-        }
       },
       async configureServer(server) {
         if (haveStarted)
@@ -97,7 +128,6 @@ export async function VitestPlugin(options: UserConfig = {}, ctx = new Vitest())
           await server.watcher.close()
       },
     },
-    EnvReplacerPlugin(),
     MocksPlugin(),
     GlobalSetupPlugin(ctx),
     options.ui

packages/vitest/src/runtime/setup.ts

@@ -8,6 +8,10 @@ import { rpc } from './rpc'
 
 let globalSetup = false
 export async function setupGlobalEnv(config: ResolvedConfig) {
+  // should be redeclared for each test
+  // if run with "threads: false"
+  setupDefines(config.defines)
+
   if (globalSetup)
     return
 
@@ -20,6 +24,11 @@ export async function setupGlobalEnv(config: ResolvedConfig) {
     (await import('../integrations/globals')).registerApiGlobally()
 }
 
+function setupDefines(defines: Record<string, any>) {
+  for (const key in defines)
+    (globalThis as any)[key] = defines[key]
+}
+
 export function setupConsoleLogSpy() {
   const stdout = new Writable({
     write(data, encoding, callback) {

packages/vitest/src/types/config.ts

@@ -324,5 +324,7 @@ export interface ResolvedConfig extends Omit<Required<UserConfig>, 'config' | 'f
 
   reporters: (Reporter | BuiltinReporters)[]
 
+  defines: Record<string, any>
+
   api?: ApiConfig
 }

test/core/test/define.test.ts

@@ -0,0 +1,55 @@
+import { afterAll, expect, test } from 'vitest'
+
+declare let __DEFINE__: string
+declare let __JSON__: any
+declare let __MODE__: string
+declare let SOME: {
+  VARIABLE: string
+  SOME: {
+    VARIABLE: string
+  }
+}
+
+// functions to test that they are not statically replaced
+const get__DEFINE__ = () => __DEFINE__
+const get__JSON__ = () => __JSON__
+const get__MODE__ = () => __MODE__
+
+const MODE = process.env.MODE
+
+afterAll(() => {
+  process.env.MODE = MODE
+})
+
+test('process.env.HELLO_PROCESS is defined on "defined" but exists on process.env', () => {
+  expect('HELLO_PROCESS' in process.env).toBe(true)
+  expect(process.env.HELLO_PROCESS).toBe('hello process')
+})
+
+test('can redeclare standard define', () => {
+  expect(get__DEFINE__()).toBe('defined')
+  __DEFINE__ = 'new defined'
+  expect(get__DEFINE__()).toBe('new defined')
+})
+
+test('can redeclare json object', () => {
+  expect(get__JSON__()).toEqual({ hello: 'world' })
+  __JSON__ = { hello: 'test' }
+  const name = '__JSON__'
+  expect(get__JSON__()).toEqual({ hello: 'test' })
+  expect((globalThis as any)[name]).toEqual({ hello: 'test' })
+})
+
+test('reassigning __MODE__', () => {
+  const env = process.env.MODE
+  expect(get__MODE__()).toBe(env)
+  process.env.MODE = 'development'
+  expect(get__MODE__()).toBe('development')
+})
+
+test('dotted defines are processed by Vite, but cannot be reassigned', () => {
+  expect(SOME.VARIABLE).toBe('variable')
+  expect(SOME.SOME.VARIABLE).toBe('nested variable')
+  SOME.VARIABLE = 'new variable'
+  expect(SOME.VARIABLE).not.toBe('new variable')
+})

test/core/vitest.config.ts

@@ -19,6 +19,16 @@ export default defineConfig({
   ],
   define: {
     'import.meta.env.TEST_NAME': '"hello world"',
+    'process.env.HELLO_PROCESS': '"hello process"',
+    // can reassign
+    '__DEFINE__': '"defined"',
+    '__JSON__': JSON.stringify({ hello: 'world' }),
+    // edge cases
+    // should not be available for reassigning as __MODE__ = 'test2'
+    // but can reassign with process.env.MODE = 'test2'
+    '__MODE__': 'process.env.MODE',
+    'SOME.VARIABLE': '"variable"',
+    'SOME.SOME.VARIABLE': '"nested variable"',
   },
   test: {
     testTimeout: 2000,