Fix #2822: Respect files package content when using file: dependencies

CHANGELOG.md

@@ -2,6 +2,12 @@
 <!-- -->
 Please add one entry in this file for each change in Yarn's behavior. Use the same format for all entries, including the third-person verb. Make sure you don't add more than one line of text to keep it clean. Thanks!
 
+## Unreleased
+
+- Respects files array when referencing dependencies via `file:`
+
+  [#8249](https://github.com/yarnpkg/yarn/pull/8249) - [**Kav**](https://github.com/kav)
+
 ## 1.22.2
 
 - Sorts files when running `yarn pack` to produce identical layout on Windows and Unix systems
@@ -35,15 +41,15 @@ Please add one entry in this file for each change in Yarn's behavior. Use the sa
 - Allows some dots in binary names again
 
   [#7811](https://github.com/yarnpkg/yarn/pull/7811) - [**Valery Bugakov**](https://github.com/valerybugakov)
-  
+
 - Better error handling on `yarn set version`
 
   [#7848](https://github.com/yarnpkg/yarn/pull/7848) - [**Nick Olinger**](https://github.com/olingern)
 
 - Passes arguments following `--` when running a workspace script (`yarn workspace pkg run command -- arg`)
 
   [#7776](https://github.com/yarnpkg/yarn/pull/7776) - [**Jeff Valore**](https://twitter.com/rally25rs)
-  
+
 - Fixes an issue where the archive paths were incorrectly sanitized
 
   [#7831](https://github.com/yarnpkg/yarn/pull/7831) - [**Maël Nison**](https://twitter.com/arcanis)
@@ -65,7 +71,7 @@ Please add one entry in this file for each change in Yarn's behavior. Use the sa
 - Implements `yarn init --install <version>`
 
   [#7723](https://github.com/yarnpkg/yarn/pull/7723) - [**Maël Nison**](https://twitter.com/arcanis)
-  
+
 ## 1.19.2
 
 - Folders like `.cache` won't be pruned from the `node_modules` after each install.

__tests__/fetchers.js

@@ -39,11 +39,11 @@ test('BaseFetcher.fetch', async () => {
 });
 
 test('CopyFetcher.fetch', async () => {
-  const a = await mkdir('copy-fetcher-a');
+  const a = await mkdir('copy-fetcher-a-');
   await fs.writeFile(path.join(a, 'package.json'), '{}');
   await fs.writeFile(path.join(a, 'foo'), 'bar');
 
-  const b = await mkdir('copy-fetcher-b');
+  const b = await mkdir('copy-fetcher-b-');
   const fetcher = new CopyFetcher(
     b,
     {
@@ -61,6 +61,32 @@ test('CopyFetcher.fetch', async () => {
   expect(contentFoo).toBe('bar');
 });
 
+test('CopyFetcher.fetch[files]', async () => {
+  const a = await mkdir('copy-fetcher-a-');
+  await fs.writeFile(path.join(a, 'package.json'), '{"files":["include"]}');
+  await fs.writeFile(path.join(a, 'include'), 'bar');
+  await fs.writeFile(path.join(a, 'exclude'), 'baz');
+
+  const b = await mkdir('copy-fetcher-b-');
+  const fetcher = await new CopyFetcher(
+    b,
+    {
+      type: 'copy',
+      reference: a,
+      registry: 'npm',
+      hash: null,
+    },
+    await Config.create(),
+  );
+  await fetcher.fetch();
+  const content = await fs.readFile(path.join(b, 'package.json'));
+  expect(content).toBe('{"files":["include"]}');
+  const contentFoo = await fs.readFile(path.join(b, 'include'));
+  expect(contentFoo).toBe('bar');
+  const excludeExists = await fs.exists(path.join(b, 'exclude'));
+  expect(excludeExists).toBe(false);
+});
+
 test('GitFetcher.fetch', async () => {
   const dir = await mkdir('git-fetcher');
   const fetcher = new GitFetcher(

src/fetchers/copy-fetcher.js

@@ -1,11 +1,36 @@
 /* @flow */
 
+import path from 'path';
 import type {FetchedOverride} from '../types.js';
 import BaseFetcher from './base-fetcher.js';
 import * as fs from '../util/fs.js';
+import {MessageError} from '../errors.js';
 
 export default class CopyFetcher extends BaseFetcher {
   async _fetch(): Promise<FetchedOverride> {
+    try {
+      const {files} = await this.config.readManifest(this.reference, this.registry);
+      if (files) {
+        await Promise.all(
+          ['package.json'].concat(files).map(fileName => {
+            const source = path.join(this.reference, fileName);
+            const destination = path.join(this.dest, fileName);
+            return fs.copy(source, destination, this.reporter);
+          }),
+        );
+
+        return {
+          hash: this.hash || '',
+          resolved: null,
+        };
+      }
+    } catch (err) {
+      if (err instanceof MessageError) {
+        this.reporter.warn(err);
+      } else {
+        throw err;
+      }
+    }
     await fs.copy(this.reference, this.dest, this.reporter);
     return {
       hash: this.hash || '',