refactor: use require.resolve instead of fs.exists (#238)

Author: atian25

.github/workflows/nodejs.yml

@@ -35,7 +35,7 @@ jobs:
         node-version: ${{ matrix.node-version }}
 
     - name: Install Dependencies
-      run: npm i -g npminstall && npminstall
+      run: npm i -g npminstall@5 && npminstall
 
     - name: Continuous Integration
       run: npm run ci

lib/loader/mixin/plugin.js

@@ -334,39 +334,31 @@ module.exports = {
     const name = plugin.package || plugin.name;
     const lookupDirs = new Set();
 
-    // try to locate the plugin in the following directories
-    //  -> {APP_PATH}/node_modules
-    //    -> {EGG_PATH}/node_modules
-    //      -> $CWD/node_modules
-    lookupDirs.add(path.join(this.options.baseDir, 'node_modules'));
+    // try to locate the plugin in the following directories's node_modules
+    // -> {APP_PATH} -> {EGG_PATH} -> $CWD
+    lookupDirs.add(this.options.baseDir);
 
     // try to locate the plugin at framework from upper to lower
     for (let i = this.eggPaths.length - 1; i >= 0; i--) {
       const eggPath = this.eggPaths[i];
-      lookupDirs.add(path.join(eggPath, 'node_modules'));
+      lookupDirs.add(eggPath);
     }
 
-    // should find the $cwd/node_modules when test the plugins under npm3
-    lookupDirs.add(path.join(process.cwd(), 'node_modules'));
+    // should find the $cwd when test the plugins under npm3
+    lookupDirs.add(process.cwd());
 
-    // should find the siblings directory of framework when using pnpm
-    for (let i = this.eggPaths.length - 1; i >= 0; i--) {
-      const eggPath = this.eggPaths[i];
+    try {
+      // should find the plugin directory
+      // pnpm will lift the node_modules to the sibling directory
       // 'node_modules/.pnpm/yadan@2.0.0/node_modules/yadan/node_modules',
       // 'node_modules/.pnpm/yadan@2.0.0/node_modules',  <- this is the sibling directory
       // 'node_modules/.pnpm/egg@2.33.1/node_modules/egg/node_modules',
       // 'node_modules/.pnpm/egg@2.33.1/node_modules', <- this is the sibling directory
-      lookupDirs.add(path.dirname(eggPath));
-    }
-
-    for (let dir of lookupDirs) {
-      dir = path.join(dir, name);
-      if (fs.existsSync(dir)) {
-        return fs.realpathSync(dir);
-      }
+      const filePath = require.resolve(`${name}/package.json`, { paths: [ ...lookupDirs ] });
+      return path.dirname(filePath);
+    } catch (_) {
+      throw new Error(`Can not find plugin ${name} in "${[ ...lookupDirs ].join(', ')}"`);
     }
-
-    throw new Error(`Can not find plugin ${name} in "${[ ...lookupDirs ].join(', ')}"`);
   },
 
   _extendPlugins(target, plugins) {