feat: warn if envPrefix contains spaces

packages/vite/src/node/__tests__/config.spec.ts

@@ -1,7 +1,7 @@
 import http from 'node:http'
 import path from 'node:path'
 import fs from 'node:fs'
-import { afterEach, describe, expect, test } from 'vitest'
+import { afterEach, describe, expect, test, vi } from 'vitest'
 import type { InlineConfig, PluginOption } from '..'
 import type { UserConfig, UserConfigExport } from '../config'
 import { defineConfig, loadConfigFromFile, resolveConfig } from '../config'
@@ -632,9 +632,22 @@ describe('resolveEnvPrefix', () => {
     expect(() => resolveEnvPrefix(config)).toThrow()
   })
 
+  test(`show a warning message if envPrefix contains a whitespace`, () => {
+    const consoleWarnSpy = vi
+      .spyOn(console, 'warn')
+      .mockImplementation(() => {})
+    let config: UserConfig = { envPrefix: 'WITH SPACE' }
+    resolveEnvPrefix(config)
+    expect(consoleWarnSpy).toHaveBeenCalled()
+    config = { envPrefix: ['CUSTOM_', 'ANOTHER SPACE'] }
+    resolveEnvPrefix(config)
+    expect(consoleWarnSpy).toHaveBeenCalledTimes(2)
+    consoleWarnSpy.mockRestore()
+  })
+
   test('should work correctly for valid envPrefix value', () => {
-    const config: UserConfig = { envPrefix: [' ', 'CUSTOM_'] }
-    expect(resolveEnvPrefix(config)).toMatchObject([' ', 'CUSTOM_'])
+    const config: UserConfig = { envPrefix: ['CUSTOM_'] }
+    expect(resolveEnvPrefix(config)).toMatchObject(['CUSTOM_'])
   })
 })
 

packages/vite/src/node/env.ts

@@ -2,6 +2,7 @@ import fs from 'node:fs'
 import path from 'node:path'
 import { parse } from 'dotenv'
 import { type DotenvPopulateInput, expand } from 'dotenv-expand'
+import colors from 'picocolors'
 import { arraify, createDebugger, normalizePath, tryStatSync } from './utils'
 import type { UserConfig } from './config'
 
@@ -99,5 +100,13 @@ export function resolveEnvPrefix({
       `envPrefix option contains value '', which could lead unexpected exposure of sensitive information.`,
     )
   }
+  if (envPrefix.some((prefix) => /\s/.test(prefix))) {
+    // eslint-disable-next-line no-console
+    console.warn(
+      colors.yellow(
+        `[vite] Warning: envPrefix option contains values with whitespace, which does not work in practice.`,
+      ),
+    )
+  }
   return envPrefix
 }