feat(kit): `addBuildPlugin` for builder-agnostic implementation (#20587)

packages/kit/src/build.ts

@@ -136,3 +136,18 @@ export function addVitePlugin (pluginOrGetter: VitePlugin | VitePlugin[] | (() =
     }
   }, options)
 }
+
+interface AddBuildPluginFactory {
+  vite?: () => VitePlugin | VitePlugin[]
+  webpack?: () => WebpackPluginInstance | WebpackPluginInstance[]
+}
+
+export function addBuildPlugin (pluginFactory: AddBuildPluginFactory, options?: ExtendConfigOptions) {
+  if (pluginFactory.vite) {
+    addVitePlugin(pluginFactory.vite, options)
+  }
+
+  if (pluginFactory.webpack) {
+    addWebpackPlugin(pluginFactory.webpack, options)
+  }
+}

test/fixtures/basic/nuxt.config.ts

@@ -1,4 +1,4 @@
-import { addComponent, addVitePlugin, addWebpackPlugin } from 'nuxt/kit'
+import { addBuildPlugin, addComponent } from 'nuxt/kit'
 import type { NuxtPage } from 'nuxt/schema'
 import { createUnplugin } from 'unplugin'
 import { withoutLeadingSlash } from 'ufo'
@@ -104,8 +104,7 @@ export default defineNuxtConfig({
           if (id === 'virtual.css') { return ':root { --virtual: red }' }
         }
       }))
-      addVitePlugin(() => plugin.vite())
-      addWebpackPlugin(() => plugin.webpack())
+      addBuildPlugin(plugin)
     },
     function (_options, nuxt) {
       const routesToDuplicate = ['/async-parent', '/fixed-keyed-child-parent', '/keyed-child-parent', '/with-layout', '/with-layout2']