feat: change runtime config using ipc signal

examples/module/test/basic.test.ts

@@ -1,26 +1,48 @@
 import { fileURLToPath } from 'node:url'
 import { describe, expect, it } from 'vitest'
-import { $fetch, setRuntimeConfig, setup } from '@nuxt/test-utils/e2e'
+import { $fetch, getBrowser, setRuntimeConfig, setup, url } from '@nuxt/test-utils/e2e'
 
 describe('ssr', async () => {
   await setup({
     rootDir: fileURLToPath(new URL('./fixtures/basic', import.meta.url)),
+    browser: true,
   })
 
   it('renders the index page', async () => {
     // Get response to a server-rendered page with `$fetch`.
     const html = await $fetch('/')
-    expect(html).toContain('<div>basic <span>original value</span></div>')
+    expect(html).toContain('<span id="runtime">original value</span></div>')
   })
 
-  it('changes runtime config and restarts', async () => {
-    const restoreConfig = await setRuntimeConfig({ public: { myValue: 'overwritten by test!' } })
+  it('changes runtime config client-side', async () => {
+    const browser = await getBrowser()
+    const page = await browser.newPage()
+    await page.goto(url('/'))
 
-    const html = await $fetch('/')
-    expect(html).toContain('<div>basic <span>overwritten by test!</span></div>')
+    const el = page.locator('#runtime')
+    expect(await el.innerText()).to.equal('original value')
+
+    await page.evaluate(() => {
+      window.__NUXT_TEST_RUNTIME_CONFIG_SETTER__({ public: { myValue: 'overwritten by test!' } })
+    })
+
+    expect(await el.innerText()).to.equal('overwritten by test!')
+  })
+
+  it('changes runtime config in server route', async () => {
+    const originalConfig = await $fetch('/api/config')
+    expect(originalConfig.public.myValue).to.equal('original value')
 
-    await restoreConfig()
-    const htmlRestored = await $fetch('/')
-    expect(htmlRestored).toContain('<div>basic <span>original value</span></div>')
+    await setRuntimeConfig({ public: { myValue: 'overwritten by test!' } })
+
+    const newConfig = await $fetch('/api/config')
+    expect(newConfig.public.myValue).to.equal('overwritten by test!')
+  })
+
+  it('changes runtime config', async () => {
+    await setRuntimeConfig({ public: { myValue: 'overwritten by test!' } })
+
+    const html = await $fetch('/')
+    expect(html).toContain('<span id="runtime">overwritten by test!</span></div>')
   })
 })

examples/module/test/fixtures/basic/app.vue

@@ -1,7 +1,9 @@
 <template>
-  <div>basic <span>{{ config.public.myValue }}</span></div>
+  <div>
+    basic <span id="runtime">{{ config.public.myValue }}</span>
+  </div>
 </template>
 
 <script setup>
-const config = useRuntimeConfig();
+const config = useRuntimeConfig()
 </script>

examples/module/test/fixtures/basic/plugins/ipc-listener.ts

@@ -0,0 +1,30 @@
+import defu from 'defu'
+import { defineNuxtPlugin } from 'nuxt/app'
+
+declare global {
+  interface Window {
+    __NUXT_TEST_RUNTIME_CONFIG_SETTER__: (env: { public: Record<string, unknown> }) => void
+  }
+}
+
+export default defineNuxtPlugin(() => {
+  const config = useRuntimeConfig()
+
+  if (process.client) {
+    window.__NUXT_TEST_RUNTIME_CONFIG_SETTER__ ??= (env: { public: Record<string, unknown> }) => {
+      config.public = defu(env.public, config.public)
+    }
+  }
+
+  if (process.server) {
+    process.on('message', (msg: { type: string; value: Record<string, string> }) => {
+      if (msg.type === 'update:runtime-config') {
+        for (const [key, value] of Object.entries(msg.value)) {
+          process.env[key] = value
+        }
+
+        process!.send!({ type: 'confirm:runtime-config' })
+      }
+    })
+  }
+})

examples/module/test/fixtures/basic/server/api/config.ts

@@ -0,0 +1,4 @@
+export default defineEventHandler(async (event) => {
+  const config = useRuntimeConfig(event)
+  return config
+})

src/core/runtime-config.ts

@@ -1,5 +1,5 @@
 import { snakeCase } from 'scule'
-import { startServer } from './server'
+import { useTestContext } from './context'
 
 export function flattenObject(obj: Record<string, unknown> = {}) {
   const flattened: Record<string, unknown> = {}
@@ -26,20 +26,36 @@ export function flattenObject(obj: Record<string, unknown> = {}) {
 
 export function convertObjectToConfig(obj: Record<string, unknown>, envPrefix: string) {
   const makeEnvKey = (str: string) => `${envPrefix}${snakeCase(str).toUpperCase()}`
-  
+
   const env: Record<string, unknown> = {}
   const flattened = flattenObject(obj)
   for (const key in flattened) {
     env[makeEnvKey(key)] = flattened[key]
   }
-  
+
   return env
 }
 
 export async function setRuntimeConfig(config: Record<string, unknown>, envPrefix = 'NUXT_') {
   const env = convertObjectToConfig(config, envPrefix)
-  await startServer({ env })
+  const ctx = useTestContext()
+
+  let updatedConfig = false
+  ctx.serverProcess?.once('message', (msg: { type: string }) => {
+    if (msg.type === 'confirm:runtime-config') {
+      updatedConfig = true
+    }
+  })
 
-  // restore
-  return async () => startServer()
+  ctx.serverProcess?.send({ type: 'update:runtime-config', value: env })
+
+  // Wait for confirmation to ensure
+  for (let i = 0; i < 10; i++) {
+    if (updatedConfig) break
+    await new Promise((resolve) => setTimeout(resolve, 1000))
+  }
+
+  if (!updatedConfig) {
+    throw new Error('Missing confirmation of runtime config update!')
+  }
 }