feat: automatically mock unresolved externals

packages/nitro/src/rollup/automock.ts

@@ -0,0 +1,16 @@
+import consola from 'consola'
+
+export function autoMock () {
+  return {
+    name: 'auto-mock',
+    resolveId (src: string) {
+      if (src && !src.startsWith('.') && !src.includes('?') && !src.includes('.js')) {
+        consola.info('Automatically mocking', src)
+        return {
+          id: require.resolve('@nuxt/un/runtime/mock/proxy')
+        }
+      }
+      return null
+    }
+  }
+}

packages/nitro/src/rollup/config.ts

@@ -19,6 +19,7 @@ import { resolvePath, MODULE_DIR } from '../utils'
 import { dynamicRequire } from './dynamic-require'
 import { externals } from './externals'
 import { timing } from './timing'
+import { autoMock } from './automock'
 
 export type RollupConfig = InputOptions & { output: OutputOptions }
 
@@ -179,6 +180,9 @@ export const getRollupConfig = (sigmaContext: SigmaContext) => {
     mainFields: ['main'] // Force resolve CJS (@vue/runtime-core ssrUtils)
   }))
 
+  // Automatically mock unresolved externals
+  rollupConfig.plugins.push(autoMock())
+
   // https://github.com/rollup/plugins/tree/master/packages/commonjs
   rollupConfig.plugins.push(commonjs({
     extensions: extensions.filter(ext => ext !== '.json')