Fix for yarnpkg#1214

__tests__/commands/install.js

@@ -775,3 +775,14 @@ test.concurrent('install uses OS line endings when lockfile doesn\'t exist', asy
       assert(lockfile.indexOf(os.EOL) >= 0);
     });
 });
+
+test.concurrent('install will not overwrite files in symlinked scoped directories', async (): Promise<void> => {
+  await runInstall({}, 'install-dont-overwrite-linked-scoped', async (config): Promise<void> => {
+    const dependencyPath = path.join(config.cwd, 'node_modules', '@fakescope', 'fake-dependency');
+    assert.equal(
+      'Symlinked scoped package test',
+      (await fs.readJson(path.join(dependencyPath, 'package.json'))).description,
+    );
+    assert.ok(!(await fs.exists(path.join(dependencyPath, 'index.js'))));
+  });
+});

__tests__/commands/remove.js

@@ -135,7 +135,7 @@ test.concurrent('removes multiple installed packages', (): Promise<void> => {
 
 test.concurrent('removes scoped packages', (): Promise<void> => {
   return runRemove({}, ['@scoped/package'], 'scoped-package', async (config): Promise<void> => {
-    assert(!await fs.exists(path.join(config.cwd, 'node_modules/@scoped')));
+    assert(!await fs.exists(path.join(config.cwd, 'node_modules/@scoped/package')));
 
     assert.deepEqual(
       JSON.parse(await fs.readFile(path.join(config.cwd, 'package.json'))).dependencies,

__tests__/fixtures/install/install-dont-overwrite-linked-scoped/.npmrc

@@ -0,0 +1 @@
+yarn-offline-mirror=./mirror-for-offline

__tests__/fixtures/install/install-dont-overwrite-linked-scoped/.yarn-link/@fakescope/fake-dependency

@@ -0,0 +1 @@
+../../dir-to-link/

__tests__/fixtures/install/install-dont-overwrite-linked-scoped/dir-to-link/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "@fakescope/fake-dependency",
+  "description": "Symlinked scoped package test",
+  "version": "1.0.1",
+  "dependencies": {},
+  "license": "MIT"
+}

__tests__/fixtures/install/install-dont-overwrite-linked-scoped/package.json

@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "@fakescope/fake-dependency": "1.0.1"
+  }
+}

__tests__/fixtures/install/install-dont-overwrite-linked-scoped/yarn.lock

@@ -0,0 +1,5 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+"@fakescope/fake-dependency@1.0.1":
+  version "1.0.1"
+  resolved "@fakescope-fake-dependency-1.0.1.tgz#477dafd486d856af0b3faf5a5f1c895001221609"

src/config.js

@@ -179,7 +179,20 @@ export default class Config {
     await fs.mkdirp(this.tempFolder);
 
     await fs.mkdirp(this.linkFolder);
-    this.linkedModules = await fs.readdir(this.linkFolder);
+
+    this.linkedModules = [];
+
+    const maybeLinkedModules = await fs.readdir(this.linkFolder);
+
+    for (const maybeLinked of maybeLinkedModules) {
+      // handle scoped modules separately
+      if (maybeLinked.indexOf('@') === 0) {
+        const scopedLinked = await fs.readdir(path.join(this.linkFolder, maybeLinked));
+        this.linkedModules.push(...scopedLinked.map((dir) => path.join(maybeLinked, dir)));
+      } else {
+        this.linkedModules.push(maybeLinked);
+      }
+    }
 
     for (const key of Object.keys(registries)) {
       const Registry = registries[key];

src/package-linker.js

@@ -115,6 +115,7 @@ export default class PackageLinker {
   }
 
   async copyModules(patterns: Array<string>): Promise<void> {
+
     let flatTree = await this.getFlatHoistedTree(patterns);
 
     // sorted tree makes file creation and copying not to interfere with each other
@@ -158,7 +159,16 @@ export default class PackageLinker {
       if (await fs.exists(loc)) {
         const files = await fs.readdir(loc);
         for (const file of files) {
-          possibleExtraneous.add(path.join(loc, file));
+          const filePath = path.join(loc, file);
+          // scoped packages are a nested one level deeper
+          if (file.indexOf('@') === 0) {
+            const scopedFiles = await fs.readdir(filePath);
+            for (const scoped of scopedFiles) {
+              possibleExtraneous.add(path.join(filePath, scoped));
+            }
+          } else {
+            possibleExtraneous.add(filePath);
+          }
         }
       }
     }