Fix lint errors 2/2

Reviewed By: jeanlauliac

Differential Revision: D4628330

fbshipit-source-id: 94fad1294e22fa0073e15843f94241ae778112a0

packages/metro-bundler/blacklist.js

@@ -29,7 +29,7 @@ function escapeRegExp(pattern) {
   } else if (typeof pattern === 'string') {
     var escaped = pattern.replace(/[\-\[\]\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&');
     // convert the '/' into an escaped local file separator
-    return escaped.replace(/\//g,'\\' + path.sep);
+    return escaped.replace(/\//g, '\\' + path.sep);
   } else {
     throw new Error('Unexpected packager blacklist pattern: ' + pattern);
   }

packages/metro-bundler/src/Bundler/__tests__/Bundle-test.js

@@ -12,7 +12,6 @@ jest.disableAutomock();
 
 const Bundle = require('../Bundle');
 const ModuleTransport = require('../../lib/ModuleTransport');
-const SourceMapGenerator = require('source-map').SourceMapGenerator;
 const crypto = require('crypto');
 
 describe('Bundle', () => {
@@ -107,33 +106,37 @@ describe('Bundle', () => {
       });
     });
 
-    it('should insert modules in a deterministic order, independent from timing of the wrapping process', () => {
+    it('inserts modules in a deterministic order, independent of timing of the wrapper process',
-      const moduleTransports = [
+      () => {
-        createModuleTransport({name: 'module1'}),
+        const moduleTransports = [
-        createModuleTransport({name: 'module2'}),
+          createModuleTransport({name: 'module1'}),
-        createModuleTransport({name: 'module3'}),
+          createModuleTransport({name: 'module2'}),
-      ];
+          createModuleTransport({name: 'module3'}),
+        ];
 
-      const resolves = {};
+        const resolves = {};
-      const resolver = {
+        const resolver = {
-        wrapModule({name}) {
+          wrapModule({name}) {
-          return new Promise(resolve => resolves[name] = resolve);
+            return new Promise(resolve => {
-        },
+              resolves[name] = resolve;
-      };
+            });
+          },
+        };
 
-      const promise = Promise.all(
+        const promise = Promise.all(moduleTransports.map(
-        moduleTransports.map(m => bundle.addModule(resolver, null, {isPolyfill: () => false}, m)))
+          m => bundle.addModule(resolver, null, {isPolyfill: () => false}, m)
-      .then(() => {
+        )).then(() => {
-        expect(bundle.getModules())
+          expect(bundle.getModules())
-          .toEqual(moduleTransports);
+            .toEqual(moduleTransports);
-      });
+        });
 
-      resolves.module2({code: ''});
+        resolves.module2({code: ''});
-      resolves.module3({code: ''});
+        resolves.module3({code: ''});
-      resolves.module1({code: ''});
+        resolves.module1({code: ''});
 
-      return promise;
+        return promise;
-    });
+      },
+    );
   });
 
   describe('sourcemap bundle', () => {
@@ -268,7 +271,6 @@ describe('Bundle', () => {
 
   describe('getEtag()', function() {
     it('should return an etag', function() {
-      var bundle = new Bundle({sourceMapUrl: 'test_url'});
       bundle.finalize({});
       var eTag = crypto.createHash('md5').update(bundle.getSource()).digest('hex');
       expect(bundle.getEtag()).toEqual(eTag);

packages/metro-bundler/src/Bundler/index.js

@@ -38,7 +38,10 @@ const VERSION = require('../../package.json').version;
 import type AssetServer from '../AssetServer';
 import type Module, {HasteImpl} from '../node-haste/Module';
 import type ResolutionResponse from '../node-haste/DependencyGraph/ResolutionResponse';
-import type {Options as JSTransformerOptions, TransformOptions} from '../JSTransformer/worker/worker';
+import type {
+  Options as JSTransformerOptions,
+  TransformOptions,
+} from '../JSTransformer/worker/worker';
 import type {Reporter} from '../lib/reporting';
 import type GlobalTransformCache from '../lib/GlobalTransformCache';
 

packages/metro-bundler/src/Bundler/source-map/encode.js

@@ -8,13 +8,14 @@
  *
  * @flow
  */
+
 /**
  * Copyright 2011 Mozilla Foundation and contributors
  * Licensed under the New BSD license. See LICENSE or:
  * http://opensource.org/licenses/BSD-3-Clause
  *
  * Based on the Base 64 VLQ implementation in Closure Compiler:
- * https://code.google.com/p/closure-compiler/source/browse/trunk/src/com/google/debugging/sourcemap/Base64VLQ.java
+ * https://git.io/vymuA
  *
  * Copyright 2011 The Closure Compiler Authors. All rights reserved.
  * Redistribution and use in source and binary forms, with or without
@@ -107,7 +108,8 @@ function toVLQSigned(value) {
  * V8 OPTIMIZATION!
  */
 function encode(value: number, buffer: Buffer, position: number): number {
-  let digit, vlq = toVLQSigned(value);
+  let vlq = toVLQSigned(value);
+  let digit;
   do {
     digit = vlq & VLQ_BASE_MASK;
     vlq >>>= VLQ_BASE_SHIFT;

packages/metro-bundler/src/JSTransformer/worker/__tests__/inline-test.js

@@ -8,6 +8,8 @@
  */
 'use strict';
 
+/* eslint-disable max-len */
+
 jest.disableAutomock();
 const inline = require('../inline');
 const {transform, transformFromAst} = require('babel-core');
@@ -205,7 +207,9 @@ describe('inline constants', () => {
       var b = a.ReactNative.Platform.select({});
     }`;
     const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
-    expect(toString(ast)).toEqual(normalize(code.replace(/ReactNative\.Platform\.select[^;]+/, '1')));
+    expect(toString(ast)).toEqual(
+      normalize(code.replace(/ReactNative\.Platform\.select[^;]+/, '1')),
+    );
   });
 
   it('replaces React.Platform.select in the code if React is a top level import', () => {
@@ -237,7 +241,9 @@ describe('inline constants', () => {
         var b = a.ReactNative.Platform.select;
       }`;
     const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
-    expect(toString(ast)).toEqual(normalize(code.replace(/ReactNative.Platform\.select[^;]+/, '2')));
+    expect(toString(ast)).toEqual(
+      normalize(code.replace(/ReactNative.Platform\.select[^;]+/, '2')),
+    );
   });
 
   it('replaces require("react-native").Platform.select in the code', () => {
@@ -269,18 +275,6 @@ describe('inline constants', () => {
       normalize(code.replace(/process\.env\.NODE_ENV/, '"production"')));
   });
 
-  it('replaces process.env.NODE_ENV in the code', () => {
-    const code = `function a() {
-      if (process.env.NODE_ENV === 'production') {
-        return require('Prod');
-      }
-      return require('Dev');
-    }`;
-    const {ast} = inline('arbitrary.js', {code}, {dev: true});
-    expect(toString(ast)).toEqual(
-      normalize(code.replace(/process\.env\.NODE_ENV/, '"development"')));
-  });
-
   it('accepts an AST as input', function() {
     const code = 'function ifDev(a,b){return __DEV__?a:b;}';
     const {ast} = inline('arbitrary.hs', {ast: toAst(code)}, {dev: false});

packages/metro-bundler/src/JSTransformer/worker/extract-dependencies.js

@@ -33,7 +33,12 @@ function extractDependencies(code: string) {
       const node = path.node;
       const callee = node.callee;
       const arg = node.arguments[0];
-      if (callee.type !== 'Identifier' || callee.name !== 'require' || !arg || arg.type !== 'StringLiteral') {
+      if (
+        callee.type !== 'Identifier' ||
+        callee.name !== 'require' ||
+        !arg ||
+        arg.type !== 'StringLiteral'
+      ) {
         return;
       }
       dependencyOffsets.push(arg.start);

packages/metro-bundler/src/ModuleGraph/__tests__/Graph-test.js

@@ -208,50 +208,52 @@ describe('Graph:', () => {
     });
   });
 
-  it('calls back with an array of modules in depth-first traversal order, regardless of the order of resolution', done => {
+  it('resolves modules in depth-first traversal order, regardless of the order of resolution',
-    load.stub.reset();
+    done => {
-    resolve.stub.reset();
+      load.stub.reset();
+      resolve.stub.reset();
 
-    const ids = [
+      const ids = [
-      'a',
+        'a',
-      'b',
+        'b',
-      'c', 'd',
+        'c', 'd',
-      'e',
+        'e',
-      'f', 'g',
+        'f', 'g',
-      'h',
+        'h',
-    ];
+      ];
-    ids.forEach(id => {
+      ids.forEach(id => {
-      const path = idToPath(id);
+        const path = idToPath(id);
-      resolve.stub.withArgs(id).yields(null, path);
+        resolve.stub.withArgs(id).yields(null, path);
-      load.stub.withArgs(path).yields(null, createFile(id), []);
+        load.stub.withArgs(path).yields(null, createFile(id), []);
-    });
+      });
-    load.stub.withArgs(idToPath('a')).yields(null, createFile('a'), ['b', 'e', 'h']);
+      load.stub.withArgs(idToPath('a')).yields(null, createFile('a'), ['b', 'e', 'h']);
-    load.stub.withArgs(idToPath('b')).yields(null, createFile('b'), ['c', 'd']);
+      load.stub.withArgs(idToPath('b')).yields(null, createFile('b'), ['c', 'd']);
-    load.stub.withArgs(idToPath('e')).yields(null, createFile('e'), ['f', 'g']);
+      load.stub.withArgs(idToPath('e')).yields(null, createFile('e'), ['f', 'g']);
 
-    // load certain ids later
+      // load certain ids later
-    ['b', 'e', 'h'].forEach(id => resolve.stub.withArgs(id).resetBehavior());
+      ['b', 'e', 'h'].forEach(id => resolve.stub.withArgs(id).resetBehavior());
-    resolve.stub.withArgs('h').func = (a, b, c, d, callback) => {
+      resolve.stub.withArgs('h').func = (a, b, c, d, callback) => {
-      callback(null, idToPath('h'));
+        callback(null, idToPath('h'));
-      ['e', 'b'].forEach(
+        ['e', 'b'].forEach(
-        id => resolve.stub.withArgs(id).yield(null, idToPath(id)));
+          id => resolve.stub.withArgs(id).yield(null, idToPath(id)));
-    };
+      };
 
-    graph(['a'], anyPlatform, noOpts, (error, result) => {
+      graph(['a'], anyPlatform, noOpts, (error, result) => {
-      expect(error).toEqual(null);
+        expect(error).toEqual(null);
-      expect(result.modules).toEqual([
+        expect(result.modules).toEqual([
-        createModule('a', ['b', 'e', 'h']),
+          createModule('a', ['b', 'e', 'h']),
-        createModule('b', ['c', 'd']),
+          createModule('b', ['c', 'd']),
-        createModule('c'),
+          createModule('c'),
-        createModule('d'),
+          createModule('d'),
-        createModule('e', ['f', 'g']),
+          createModule('e', ['f', 'g']),
-        createModule('f'),
+          createModule('f'),
-        createModule('g'),
+          createModule('g'),
-        createModule('h'),
+          createModule('h'),
-      ]);
+        ]);
-      done();
+        done();
-    });
+      });
-  });
+    },
+  );
 
   it('calls back with the resolved modules of the entry points', done => {
     load.stub.reset();
@@ -274,7 +276,7 @@ describe('Graph:', () => {
     });
   });
 
-  it('calls back with the resolved modules of the entry points if one entry point is a dependency of another', done => {
+  it('resolves modules for all entry points correctly if one is a dependency of another', done => {
     load.stub.reset();
     resolve.stub.reset();
 

packages/metro-bundler/src/ModuleGraph/node-haste/HasteFS.js

@@ -25,7 +25,9 @@ module.exports = class HasteFS {
   }
 
   closest(path: string, fileName: string): ?string {
-    let {dir, root} = parse(path);
+    const parsedPath = parse(path);
+    const root = parsedPath.root;
+    let dir = parsedPath.dir;
     do {
       const candidate = join(dir, fileName);
       if (this.files.has(candidate)) {
@@ -63,7 +65,9 @@ module.exports = class HasteFS {
 function buildDirectorySet(files) {
   const directories = new Set();
   files.forEach(path => {
-    let {dir, root} = parse(path);
+    const parsedPath = parse(path);
+    const root = parsedPath.root;
+    let dir = parsedPath.dir;
     while (dir !== '.' && dir !== root && !directories.has(dir)) {
       directories.add(dir);
       dir = dirname(dir);

packages/metro-bundler/src/ModuleGraph/worker/__tests__/collect-dependencies-test.js

@@ -63,27 +63,29 @@ describe('dependency collection from ASTs:', () => {
       .toEqual(any(String));
   });
 
-  it('replaces all required module ID strings with array lookups and keeps the ID as second argument', () => {
+  it('replaces all required module ID strings with array lookups, keeps the ID as second argument',
-    const ast = astFromCode(`
+    () => {
-      const a = require('b/lib/a');
+      const ast = astFromCode(`
-      const b = require(123);
+        const a = require('b/lib/a');
-      exports.do = () => require("do");
+        const b = require(123);
-      if (!something) {
+        exports.do = () => require("do");
-        require("setup/something");
+        if (!something) {
-      }
+          require("setup/something");
-    `);
+        }
+      `);
 
-    const {dependencyMapName} = collectDependencies(ast);
+      const {dependencyMapName} = collectDependencies(ast);
 
-    expect(codeFromAst(ast)).toEqual(comparableCode(`
+      expect(codeFromAst(ast)).toEqual(comparableCode(`
-      const a = require(${dependencyMapName}[0], 'b/lib/a');
+        const a = require(${dependencyMapName}[0], 'b/lib/a');
-      const b = require(123);
+        const b = require(123);
-      exports.do = () => require(${dependencyMapName}[1], "do");
+        exports.do = () => require(${dependencyMapName}[1], "do");
-      if (!something) {
+        if (!something) {
-        require(${dependencyMapName}[2], "setup/something");
+          require(${dependencyMapName}[2], "setup/something");
-      }
+        }
-    `));
+      `));
-  });
+    },
+  );
 });
 
 describe('Dependency collection from optimized ASTs:', () => {

packages/metro-bundler/src/ModuleGraph/worker/__tests__/optimize-module-test.js

@@ -94,4 +94,5 @@ function findLast(code, needle) {
       return {line: line + 1, column};
     }
   }
+  return null;
 }

packages/metro-bundler/src/ModuleGraph/worker/__tests__/transform-module-test.js

@@ -19,8 +19,6 @@ const {parse} = require('babylon');
 const generate = require('babel-generator').default;
 const {traverse} = require('babel-core');
 
-const {any, objectContaining} = jasmine;
-
 describe('transforming JS modules:', () => {
   const filename = 'arbitrary';
 
@@ -47,7 +45,7 @@ describe('transforming JS modules:', () => {
 
   it('passes through file name and code', done => {
     transformModule(sourceCode, options(), (error, result) => {
-      expect(result).toEqual(objectContaining({
+      expect(result).toEqual(expect.objectContaining({
         code: sourceCode,
         file: filename,
       }));
@@ -59,36 +57,39 @@ describe('transforming JS modules:', () => {
     const hasteID = 'TheModule';
     const codeWithHasteID = `/** @providesModule ${hasteID} */`;
     transformModule(codeWithHasteID, options(), (error, result) => {
-      expect(result).toEqual(objectContaining({hasteID}));
+      expect(result).toEqual(expect.objectContaining({hasteID}));
       done();
     });
   });
 
   it('sets `type` to `"module"` by default', done => {
     transformModule(sourceCode, options(), (error, result) => {
-      expect(result).toEqual(objectContaining({type: 'module'}));
+      expect(result).toEqual(expect.objectContaining({type: 'module'}));
       done();
     });
   });
 
   it('sets `type` to `"script"` if the input is a polyfill', done => {
     transformModule(sourceCode, {...options(), polyfill: true}, (error, result) => {
-      expect(result).toEqual(objectContaining({type: 'script'}));
+      expect(result).toEqual(expect.objectContaining({type: 'script'}));
       done();
     });
   });
 
-  it('calls the passed-in transform function with code, file name, and options for all passed in variants', done => {
+  it('calls the passed-in transform function with code, file name, and options ' +
-    const variants = {dev: {dev: true}, prod: {dev: false}};
+    'for all passed in variants',
+    done => {
+      const variants = {dev: {dev: true}, prod: {dev: false}};
 
-    transformModule(sourceCode, options(variants), () => {
+      transformModule(sourceCode, options(variants), () => {
-      expect(transformer.transform)
+        expect(transformer.transform)
-        .toBeCalledWith(sourceCode, filename, variants.dev);
+          .toBeCalledWith(sourceCode, filename, variants.dev);
-      expect(transformer.transform)
+        expect(transformer.transform)
-        .toBeCalledWith(sourceCode, filename, variants.prod);
+          .toBeCalledWith(sourceCode, filename, variants.prod);
-      done();
+        done();
-    });
+      });
-  });
+    },
+  );
 
   it('calls back with any error yielded by the transform function', done => {
     const error = new Error();
@@ -114,7 +115,7 @@ describe('transforming JS modules:', () => {
     });
   });
 
-  it('wraps the code produced by the transform function into an immediately invoked function expression for polyfills', done => {
+  it('wraps the code produced by the transform function into an IIFE for polyfills', done => {
     transformModule(sourceCode, {...options(), polyfill: true}, (error, result) => {
       expect(error).toEqual(null);
 
@@ -131,20 +132,21 @@ describe('transforming JS modules:', () => {
       const column = code.indexOf('code');
       const consumer = new SourceMapConsumer(map);
       expect(consumer.originalPositionFor({line: 1, column}))
-        .toEqual(objectContaining({line: 1, column: sourceCode.indexOf('code')}));
+        .toEqual(expect.objectContaining({line: 1, column: sourceCode.indexOf('code')}));
       done();
     });
   });
 
   it('extracts dependencies (require calls)', done => {
-    const dep1 = 'foo', dep2 = 'bar';
+    const dep1 = 'foo';
+    const dep2 = 'bar';
     const code = `require('${dep1}'),require('${dep2}')`;
     const {body} = parse(code).program;
     transformer.transform.stub.returns(transformResult(body));
 
     transformModule(code, options(), (error, result) => {
       expect(result.transformed.default)
-        .toEqual(objectContaining({dependencies: [dep1, dep2]}));
+        .toEqual(expect.objectContaining({dependencies: [dep1, dep2]}));
       done();
     });
   });
@@ -190,7 +192,7 @@ describe('transforming JS modules:', () => {
   it('does not create source maps for JSON files', done => {
     transformModule('{}', {...options(), filename: 'some.json'}, (error, result) => {
       expect(result.transformed.default)
-        .toEqual(objectContaining({map: null}));
+        .toEqual(expect.objectContaining({map: null}));
       done();
     });
   });

packages/metro-bundler/src/ModuleGraph/worker/transform-module.js

@@ -44,7 +44,8 @@ function transformModule(
   callback: Callback<TransformedFile>,
 ): void {
   if (options.filename.endsWith('.json')) {
-    return transformJSON(code, options, callback);
+    transformJSON(code, options, callback);
+    return;
   }
 
   const {filename, transformer, variants = defaultVariants} = options;
@@ -86,6 +87,7 @@ function transformModule(
       type: options.polyfill ? 'script' : 'module',
     });
   });
+  return;
 }
 
 function transformJSON(json, options, callback) {

packages/metro-bundler/src/Resolver/__tests__/Resolver-test.js

@@ -237,40 +237,6 @@ describe('Resolver', function() {
         });
     });
 
-    it('should get dependencies with polyfills', function() {
-      var module = createModule('index');
-      var deps = [module];
-
-      var depResolver = new Resolver({
-        projectRoot: '/root',
-      });
-
-      DependencyGraph.prototype.getDependencies.mockImplementation(function() {
-        return Promise.resolve(new ResolutionResponseMock({
-          dependencies: deps,
-          mainModuleId: 'index',
-        }));
-      });
-
-      const polyfill = {};
-      DependencyGraph.prototype.createPolyfill.mockReturnValueOnce(polyfill);
-      return depResolver
-        .getDependencies(
-          '/root/index.js',
-          {dev: true},
-          undefined,
-          undefined,
-          createGetModuleId()
-        ).then(function(result) {
-          expect(result.mainModuleId).toEqual('index');
-          expect(DependencyGraph.mock.instances[0].getDependencies)
-              .toBeCalledWith({entryPath: '/root/index.js', recursive: true});
-          expect(result.dependencies[0]).toBe(polyfill);
-          expect(result.dependencies[result.dependencies.length - 1])
-              .toBe(module);
-        });
-    });
-
     it('should pass in more polyfills', function() {
       var module = createModule('index');
       var deps = [module];
@@ -296,7 +262,9 @@ describe('Resolver', function() {
           createGetModuleId()
         ).then(result => {
           expect(result.mainModuleId).toEqual('index');
-          expect(DependencyGraph.prototype.createPolyfill.mock.calls[result.dependencies.length - 2]).toEqual([
+          const calls =
+            DependencyGraph.prototype.createPolyfill.mock.calls[result.dependencies.length - 2];
+          expect(calls).toEqual([
             {file: 'some module',
               id: 'some module',
               dependencies: [
@@ -444,7 +412,8 @@ describe('Resolver', function() {
         expect(processedCode).toEqual([
           '(function(global) {',
           'global.fetch = () => 1;',
-          "\n})(typeof global !== 'undefined' ? global : typeof self !== 'undefined' ? self : this);",
+          '\n})' +
+          "(typeof global !== 'undefined' ? global : typeof self !== 'undefined' ? self : this);",
         ].join(''));
       });
     });

packages/metro-bundler/src/Resolver/index.js

@@ -76,7 +76,8 @@ class Resolver {
       },
       platforms: new Set(opts.platforms),
       preferNativePlatform: true,
-      providesModuleNodeModules: opts.providesModuleNodeModules || defaults.providesModuleNodeModules,
+      providesModuleNodeModules:
+        opts.providesModuleNodeModules || defaults.providesModuleNodeModules,
       reporter: opts.reporter,
       resetCache: opts.resetCache,
       roots: opts.projectRoots,
@@ -261,7 +262,7 @@ function defineModuleCode(moduleName, code, verboseName = '', dev = true) {
   ].join('');
 }
 
-function definePolyfillCode(code,) {
+function definePolyfillCode(code) {
   return [
     '(function(global) {',
     code,

packages/metro-bundler/src/Resolver/polyfills/Number.es6.js

@@ -27,6 +27,7 @@ if (Number.MIN_SAFE_INTEGER === undefined) {
   });
 }
 if (!Number.isNaN) {
+  // eslint-disable-next-line max-len
   // https://github.com/dherman/tc39-codex-wiki/blob/master/data/es6/number/index.md#polyfill-for-numberisnan
   const globalIsNaN = global.isNaN;
   Object.defineProperty(Number, 'isNaN', {

packages/metro-bundler/src/Resolver/polyfills/error-guard.js

@@ -52,6 +52,7 @@ const ErrorUtils = {
     } finally {
       _inGuard--;
     }
+    return null;
   },
   applyWithGuardIfNeeded(fun, context, args) {
     if (ErrorUtils.inGuard()) {
@@ -59,6 +60,7 @@ const ErrorUtils = {
     } else {
       ErrorUtils.applyWithGuard(fun, context, args);
     }
+    return null;
   },
   inGuard() {
     return _inGuard;

packages/metro-bundler/src/Server/index.js

@@ -43,7 +43,8 @@ const {
 } = require('../Logger');
 
 function debounceAndBatch(fn, delay) {
-  let timeout, args = [];
+  let args = [];
+  let timeout;
   return value => {
     args.push(value);
     clearTimeout(timeout);
@@ -957,7 +958,8 @@ class Server {
         'entryModuleOnly',
         false,
       ),
-      generateSourceMaps: minify || !dev || this._getBoolOptionFromQuery(urlObj.query, 'babelSourcemap', false),
+      generateSourceMaps:
+        minify || !dev || this._getBoolOptionFromQuery(urlObj.query, 'babelSourcemap', false),
       assetPlugins,
     };
   }

packages/metro-bundler/src/lib/relativizeSourceMap.js

@@ -17,11 +17,11 @@ import type {MixedSourceMap} from './SourceMap';
 
 function relativizeSourceMapInternal(sourceMap: any, sourcesRoot: string) {
   if (sourceMap.sections) {
-    for (var i = 0; i < sourceMap.sections.length; i++) {
+    for (let i = 0; i < sourceMap.sections.length; i++) {
       relativizeSourceMapInternal(sourceMap.sections[i].map, sourcesRoot);
     }
   } else {
-    for (var i = 0; i < sourceMap.sources.length; i++) {
+    for (let i = 0; i < sourceMap.sources.length; i++) {
       sourceMap.sources[i] = path.relative(sourcesRoot, sourceMap.sources[i]);
     }
   }

packages/metro-bundler/src/node-haste/DependencyGraph/HasteMap.js

@@ -87,6 +87,7 @@ class HasteMap extends EventEmitter {
           return this._processHasteModule(absPath, invalidated);
         }
       }
+      return null;
     });
   }
 

packages/metro-bundler/src/node-haste/__mocks__/graceful-fs.js

@@ -37,7 +37,7 @@ fs.realpath.mockImplementation((filepath, callback) => {
   if (node && typeof node === 'object' && node.SYMLINK != null) {
     return callback(null, node.SYMLINK);
   }
-  callback(null, filepath);
+  return callback(null, filepath);
 });
 
 fs.readdirSync.mockImplementation(filepath => Object.keys(getToNode(filepath)));
@@ -58,7 +58,7 @@ fs.readdir.mockImplementation((filepath, callback) => {
     return callback(new Error(filepath + ' is not a directory.'));
   }
 
-  callback(null, Object.keys(node));
+  return callback(null, Object.keys(node));
 });
 
 fs.readFile.mockImplementation(function(filepath, encoding, callback) {
@@ -76,9 +76,9 @@ fs.readFile.mockImplementation(function(filepath, encoding, callback) {
       callback(new Error('Error readFile a dir: ' + filepath));
     }
     if (node == null) {
-      callback(Error('No such file: ' + filepath));
+      return callback(Error('No such file: ' + filepath));
     } else {
-      callback(null, node);
+      return callback(null, node);
     }
   } catch (e) {
     return callback(e);

packages/metro-bundler/src/node-haste/__tests__/DependencyGraph-test.js

@@ -748,7 +748,7 @@ describe('DependencyGraph', function() {
       });
     });
 
-    it('should work with packages', function() {
+    it('should work with packages with a trailing slash', function() {
       var root = '/root';
       setMockFileSystem({
         'root': {

packages/metro-bundler/src/node-haste/index.js

@@ -130,7 +130,9 @@ class DependencyGraph extends EventEmitter {
         moduleOptions: this._opts.moduleOptions,
         reporter: this._opts.reporter,
         getClosestPackage: filePath => {
-          let {dir, root} = path.parse(filePath);
+          const parsedPath = path.parse(filePath);
+          const root = parsedPath.root;
+          let dir = parsedPath.dir;
           do {
             const candidate = path.join(dir, 'package.json');
             if (this._hasteFS.exists(candidate)) {

packages/metro-bundler/transformer.js

@@ -35,7 +35,7 @@ const getBabelRC = (function() {
       return babelRC;
     }
 
-    babelRC = { plugins: [] }; // empty babelrc
+    babelRC = {plugins: []}; // empty babelrc
 
     // Let's look for the .babelrc in the first project root.
     // In the future let's look into adding a command line option to specify
@@ -54,7 +54,7 @@ const getBabelRC = (function() {
         );
 
       // Require the babel-preset's listed in the default babel config
-      babelRC.presets = babelRC.presets.map((preset) => require('babel-preset-' + preset));
+      babelRC.presets = babelRC.presets.map(preset => require('babel-preset-' + preset));
       babelRC.plugins = resolvePlugins(babelRC.plugins);
     } else {
       // if we find a .babelrc file we tell babel to use it