Implements the enable-meta-folder (#3367)

* Implements the enable-meta-folder

* Adds enable-meta-folder support to yarn-error.log

.gitignore

@@ -20,3 +20,4 @@ test/fixtures/**/.fbkpm
 /__tests__/fixtures/**/_*
 /__tests__/fixtures/request-cache/GET/localhost/.bin
 .idea
+.yarn-meta

__tests__/commands/check.js

@@ -258,3 +258,11 @@ test.concurrent('--integrity should fail if integrity file have different linked
     expect(getStdout()).toContain('Integrity check: Linked modules don\'t match');
   });
 });
+
+test('--integrity should create the integrity file under the meta folder if enabled', async (): Promise<void> => {
+  await runInstall({}, path.join('..', 'check', 'integrity-meta-folder'),
+  async (config, reporter, install, getStdout): Promise<void> => {
+    await checkCmd.run(config, reporter, {integrity: true}, []);
+    expect(await fs.exists(path.join(config.cwd, '.yarn-meta', '.yarn-integrity'))).toEqual(true);
+  });
+});

__tests__/fixtures/check/integrity-meta-folder/.yarnrc

@@ -0,0 +1 @@
+enable-meta-folder true

__tests__/fixtures/check/integrity-meta-folder/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "a",
+  "version": "1.0.0"
+}

src/cli/index.js

@@ -287,7 +287,9 @@ function onUnexpectedError(err: Error) {
 }
 
 function writeErrorReport(log) : ?string {
-  const errorReportLoc = path.join(config.cwd, 'yarn-error.log');
+  const errorReportLoc = config.enableMetaFolder
+    ? path.join(config.cwd, constants.META_FOLDER, 'yarn-error.log')
+    : path.join(config.cwd, 'yarn-error.log');
 
   try {
     fs.writeFileSync(errorReportLoc, log.join('\n\n') + '\n');

src/config.js

@@ -30,6 +30,7 @@ export type ConfigOptions = {
   offline?: boolean,
   preferOffline?: boolean,
   pruneOfflineMirror?: boolean,
+  enableMetaFolder?: boolean,
   captureHar?: boolean,
   ignoreScripts?: boolean,
   ignorePlatform?: boolean,
@@ -89,6 +90,7 @@ export default class Config {
   offline: boolean;
   preferOffline: boolean;
   pruneOfflineMirror: boolean;
+  enableMetaFolder: boolean;
   disableLockfileVersions: boolean;
   ignorePlatform: boolean;
   binLinks: boolean;
@@ -266,6 +268,7 @@ export default class Config {
     );
 
     this.pruneOfflineMirror = Boolean(this.getOption('yarn-offline-mirror-pruning'));
+    this.enableMetaFolder = Boolean(this.getOption('enable-meta-folder'));
     this.disableLockfileVersions = Boolean(this.getOption('yarn-disable-lockfile-versions'));
 
     //init & create cacheFolder, tempFolder

src/constants.js

@@ -64,6 +64,7 @@ export const CONFIG_DIRECTORY = getDirectory('config');
 export const LINK_REGISTRY_DIRECTORY = path.join(CONFIG_DIRECTORY, 'link');
 export const GLOBAL_MODULE_DIRECTORY = path.join(CONFIG_DIRECTORY, 'global');
 
+export const META_FOLDER = '.yarn-meta';
 export const INTEGRITY_FILENAME = '.yarn-integrity';
 export const LOCKFILE_FILENAME = 'yarn.lock';
 export const METADATA_FILENAME = '.yarn-metadata.json';

src/integrity-checker.js

@@ -69,37 +69,46 @@ export default class InstallationIntegrityChecker {
    */
 
   async _getIntegrityHashLocation(usedRegistries?: Set<RegistryNames>): Promise<IntegrityHashLocation> {
-    // build up possible folders
-    let registries = registryNames;
-    if (usedRegistries && usedRegistries.size > 0) {
-      registries = usedRegistries;
-    }
-    const possibleFolders = [];
-    if (this.config.modulesFolder) {
-      possibleFolders.push(this.config.modulesFolder);
-    }
+    let locationFolder;
+
+    if (this.config.enableMetaFolder) {
+      locationFolder = path.join(this.config.cwd, constants.META_FOLDER);
+    } else {
+      // build up possible folders
+      let registries = registryNames;
+      if (usedRegistries && usedRegistries.size > 0) {
+        registries = usedRegistries;
+      }
+      const possibleFolders = [];
+      if (this.config.modulesFolder) {
+        possibleFolders.push(this.config.modulesFolder);
+      }
 
-    // ensure we only write to a registry folder that was used
-    for (const name of registries) {
-      const loc = path.join(this.config.cwd, this.config.registries[name].folder);
-      possibleFolders.push(loc);
-    }
+      // ensure we only write to a registry folder that was used
+      for (const name of registries) {
+        const loc = path.join(this.config.cwd, this.config.registries[name].folder);
+        possibleFolders.push(loc);
+      }
 
-    // if we already have an integrity hash in one of these folders then use it's location otherwise use the
-    // first folder
-    let loc;
-    for (const possibleLoc of possibleFolders) {
-      if (await fs.exists(path.join(possibleLoc, constants.INTEGRITY_FILENAME))) {
-        loc = possibleLoc;
-        break;
+      // if we already have an integrity hash in one of these folders then use it's location otherwise use the
+      // first folder
+      let loc;
+      for (const possibleLoc of possibleFolders) {
+        if (await fs.exists(path.join(possibleLoc, constants.INTEGRITY_FILENAME))) {
+          loc = possibleLoc;
+          break;
+        }
       }
+      locationFolder = loc || possibleFolders[0];
     }
-    const locationFolder = loc || possibleFolders[0];
+
     const locationPath = path.join(locationFolder, constants.INTEGRITY_FILENAME);
+    const exists = await fs.exists(locationPath);
+
     return {
       locationFolder,
       locationPath,
-      exists: !!loc,
+      exists,
     };
   }