✨ Add minimal watch example. API to be simplified in the future.

Concept taken from comment by <hi-ogawa, Hiroshi Ogawa> - vitest-dev/vitest#6457 (comment) and their example at https://stackblitz.com/edit/vitest-dev-vitest-qq31nt?file=vite.config.ts

Author: klondikemarlen

src/plugin.ts

@@ -1,11 +1,25 @@
 import { Plugin } from "rollup"
 
-export function guardLikeWatch(): Plugin {
+export type Watch = {
+  pattern: RegExp | string
+  action: (match: RegExpMatchArray, id: string) => string[]
+}
+
+export function guardLikeWatch(watches: Watch[]): Plugin {
   return {
     name: "vite-plugin-guard-like-watch",
     transform(_code, id) {
-      console.log(`id:`, id)
-    }
+      for (const watch of watches) {
+        const regexp = new RegExp(watch.pattern)
+        const match = id.match(regexp)
+        if (match === null || match === undefined) return
+
+        const filesToWatch = watch.action(match, id)
+        for (const file of filesToWatch) {
+          this.addWatchFile(file)
+        }
+      }
+    },
   }
 }
 

vite.config.mts

@@ -12,7 +12,14 @@ export default defineConfig({
       root: ".",
       projects: ["./tsconfig.json", "./tests/tsconfig.json"],
     }),
-    guardLikeWatch(),
+    guardLikeWatch([
+      {
+        pattern: /(.*\/example)\.ts/,
+        action(match) {
+          return [`${match[1]}.html`, `${match[1]}.txt`]
+        },
+      },
+    ]),
   ],
   test: {
     globals: true,