diff --git a/packages/metro-bundler/src/node-haste/__mocks__/fs.js b/packages/metro-bundler/src/node-haste/__mocks__/fs.js
index 2036e6ea..41ad4f1c 100644
--- a/packages/metro-bundler/src/node-haste/__mocks__/fs.js
+++ b/packages/metro-bundler/src/node-haste/__mocks__/fs.js
@@ -8,4 +8,301 @@
  */
 'use strict';
 
-module.exports = require('graceful-fs');
+const {EventEmitter} = require('events');
+const {dirname} = require.requireActual('path');
+const fs = jest.genMockFromModule('fs');
+const path = require('path');
+const stream = require.requireActual('stream');
+
+const noop = () => {};
+
+function asyncCallback(cb) {
+  return function() {
+    setImmediate(() => cb.apply(this, arguments));
+  };
+}
+
+const mtime = {
+  getTime: () => Math.ceil(Math.random() * 10000000),
+};
+
+fs.realpath.mockImplementation((filepath, callback) => {
+  callback = asyncCallback(callback);
+  let node;
+  try {
+    node = getToNode(filepath);
+  } catch (e) {
+    return callback(e);
+  }
+  if (node && typeof node === 'object' && node.SYMLINK != null) {
+    return callback(null, node.SYMLINK);
+  }
+  return callback(null, filepath);
+});
+
+fs.readdirSync.mockImplementation(filepath => Object.keys(getToNode(filepath)));
+
+fs.readdir.mockImplementation((filepath, callback) => {
+  callback = asyncCallback(callback);
+  let node;
+  try {
+    node = getToNode(filepath);
+    if (node && typeof node === 'object' && node.SYMLINK != null) {
+      node = getToNode(node.SYMLINK);
+    }
+  } catch (e) {
+    return callback(e);
+  }
+
+  if (!(node && typeof node === 'object' && node.SYMLINK == null)) {
+    return callback(new Error(filepath + ' is not a directory.'));
+  }
+
+  return callback(null, Object.keys(node));
+});
+
+fs.readFile.mockImplementation(function(filepath, encoding, callback) {
+  callback = asyncCallback(callback);
+  if (arguments.length === 2) {
+    callback = encoding;
+    encoding = null;
+  }
+
+  let node;
+  try {
+    node = getToNode(filepath);
+    // dir check
+    if (node && typeof node === 'object' && node.SYMLINK == null) {
+      callback(new Error('Error readFile a dir: ' + filepath));
+    }
+    if (node == null) {
+      return callback(Error('No such file: ' + filepath));
+    } else {
+      return callback(null, node);
+    }
+  } catch (e) {
+    return callback(e);
+  }
+});
+
+fs.readFileSync.mockImplementation(function(filepath, encoding) {
+  const node = getToNode(filepath);
+  // dir check
+  if (node && typeof node === 'object' && node.SYMLINK == null) {
+    throw new Error('Error readFileSync a dir: ' + filepath);
+  }
+  return node;
+});
+
+function makeStatResult(node) {
+  const isSymlink = node != null && node.SYMLINK != null;
+  return {
+    isBlockDevice: () => false,
+    isCharacterDevice: () => false,
+    isDirectory: () => node != null && typeof node === 'object' && !isSymlink,
+    isFIFO: () => false,
+    isFile: () => node != null && typeof node === 'string',
+    isSocket: () => false,
+    isSymbolicLink: () => isSymlink,
+    mtime,
+  };
+}
+
+function statSync(filepath) {
+  const node = getToNode(filepath);
+  if (node != null && node.SYMLINK) {
+    return statSync(node.SYMLINK);
+  }
+  return makeStatResult(node);
+}
+
+fs.stat.mockImplementation((filepath, callback) => {
+  callback = asyncCallback(callback);
+  let result;
+  try {
+    result = statSync(filepath);
+  } catch (e) {
+    callback(e);
+    return;
+  }
+  callback(null, result);
+});
+
+fs.statSync.mockImplementation(statSync);
+
+function lstatSync(filepath) {
+  const node = getToNode(filepath);
+  return makeStatResult(node);
+}
+
+fs.lstat.mockImplementation((filepath, callback) => {
+  callback = asyncCallback(callback);
+  let result;
+  try {
+    result = lstatSync(filepath);
+  } catch (e) {
+    callback(e);
+    return;
+  }
+  callback(null, result);
+});
+
+fs.lstatSync.mockImplementation(lstatSync);
+
+fs.open.mockImplementation(function(filepath) {
+  const callback = arguments[arguments.length - 1] || noop;
+  let data, error, fd;
+  try {
+    data = getToNode(filepath);
+  } catch (e) {
+    error = e;
+  }
+
+  if (error || data == null) {
+    error = Error(`ENOENT: no such file or directory, open ${filepath}`);
+  }
+  if (data != null) {
+    /* global Buffer: true */
+    fd = {buffer: new Buffer(data, 'utf8'), position: 0};
+  }
+
+  callback(error, fd);
+});
+
+fs.read.mockImplementation((fd, buffer, writeOffset, length, position, callback = noop) => {
+  let bytesWritten;
+  try {
+    if (position == null || position < 0) {
+      ({position} = fd);
+    }
+    bytesWritten = fd.buffer.copy(buffer, writeOffset, position, position + length);
+    fd.position = position + bytesWritten;
+  } catch (e) {
+    callback(Error('invalid argument'));
+    return;
+  }
+  callback(null, bytesWritten, buffer);
+});
+
+fs.close.mockImplementation((fd, callback = noop) => {
+  try {
+    fd.buffer = fs.position = undefined;
+  } catch (e) {
+    callback(Error('invalid argument'));
+    return;
+  }
+  callback(null);
+});
+
+let filesystem;
+
+fs.createReadStream.mockImplementation(filepath => {
+  if (!filepath.startsWith('/')) {
+    throw Error('Cannot open file ' + filepath);
+  }
+
+  const parts = filepath.split('/').slice(1);
+  let file = filesystem;
+
+  for (const part of parts) {
+    file = file[part];
+    if (!file) {
+      break;
+    }
+  }
+
+  if (typeof file !== 'string') {
+    throw Error('Cannot open file ' + filepath);
+  }
+
+  return new stream.Readable({
+    read() {
+      this.push(file, 'utf8');
+      this.push(null);
+    },
+  });
+});
+
+fs.createWriteStream.mockImplementation(file => {
+  let node;
+  try {
+    node = getToNode(dirname(file));
+  } finally {
+    if (typeof node === 'object') {
+      const writeStream = new stream.Writable({
+        write(chunk) {
+          this.__chunks.push(chunk);
+        },
+      });
+      writeStream.__file = file;
+      writeStream.__chunks = [];
+      writeStream.end = jest.fn(writeStream.end);
+      fs.createWriteStream.mock.returned.push(writeStream);
+      return writeStream;
+    } else {
+      throw new Error('Cannot open file ' + file);
+    }
+  }
+});
+fs.createWriteStream.mock.returned = [];
+
+fs.__setMockFilesystem = object => (filesystem = object);
+
+const watcherListByPath = new Map();
+
+fs.watch.mockImplementation((filename, options, listener) => {
+  if (options.recursive) {
+    throw new Error('recursive watch not implemented');
+  }
+  let watcherList = watcherListByPath.get(filename);
+  if (watcherList == null) {
+    watcherList = [];
+    watcherListByPath.set(filename, watcherList);
+  }
+  const fsWatcher = new EventEmitter();
+  fsWatcher.on('change', listener);
+  fsWatcher.close = () => {
+    watcherList.splice(watcherList.indexOf(fsWatcher), 1);
+    fsWatcher.close = () => { throw new Error('FSWatcher is already closed'); };
+  };
+  watcherList.push(fsWatcher);
+});
+
+fs.__triggerWatchEvent = (eventType, filename) => {
+  const directWatchers = watcherListByPath.get(filename) || [];
+  directWatchers.forEach(wtc => wtc.emit('change', eventType));
+  const dirPath = path.dirname(filename);
+  const dirWatchers = watcherListByPath.get(dirPath) || [];
+  dirWatchers.forEach(wtc => wtc.emit('change', eventType, path.relative(dirPath, filename)));
+};
+
+function getToNode(filepath) {
+  // Ignore the drive for Windows paths.
+  if (filepath.match(/^[a-zA-Z]:\\/)) {
+    filepath = filepath.substring(2);
+  }
+
+  if (filepath.endsWith(path.sep)) {
+    filepath = filepath.slice(0, -1);
+  }
+  const parts = filepath.split(/[\/\\]/);
+  if (parts[0] !== '') {
+    throw new Error('Make sure all paths are absolute.');
+  }
+  let node = filesystem;
+  parts.slice(1).forEach(part => {
+    if (node && node.SYMLINK) {
+      node = getToNode(node.SYMLINK);
+    }
+    node = node[part];
+    if (node == null) {
+      const err = new Error('ENOENT: no such file or directory');
+      err.code = 'ENOENT';
+      throw err;
+    }
+  });
+
+  return node;
+}
+
+module.exports = fs;
diff --git a/packages/metro-bundler/src/node-haste/__mocks__/graceful-fs.js b/packages/metro-bundler/src/node-haste/__mocks__/graceful-fs.js
index 41ad4f1c..71b31aa2 100644
--- a/packages/metro-bundler/src/node-haste/__mocks__/graceful-fs.js
+++ b/packages/metro-bundler/src/node-haste/__mocks__/graceful-fs.js
@@ -8,301 +8,4 @@
  */
 'use strict';
 
-const {EventEmitter} = require('events');
-const {dirname} = require.requireActual('path');
-const fs = jest.genMockFromModule('fs');
-const path = require('path');
-const stream = require.requireActual('stream');
-
-const noop = () => {};
-
-function asyncCallback(cb) {
-  return function() {
-    setImmediate(() => cb.apply(this, arguments));
-  };
-}
-
-const mtime = {
-  getTime: () => Math.ceil(Math.random() * 10000000),
-};
-
-fs.realpath.mockImplementation((filepath, callback) => {
-  callback = asyncCallback(callback);
-  let node;
-  try {
-    node = getToNode(filepath);
-  } catch (e) {
-    return callback(e);
-  }
-  if (node && typeof node === 'object' && node.SYMLINK != null) {
-    return callback(null, node.SYMLINK);
-  }
-  return callback(null, filepath);
-});
-
-fs.readdirSync.mockImplementation(filepath => Object.keys(getToNode(filepath)));
-
-fs.readdir.mockImplementation((filepath, callback) => {
-  callback = asyncCallback(callback);
-  let node;
-  try {
-    node = getToNode(filepath);
-    if (node && typeof node === 'object' && node.SYMLINK != null) {
-      node = getToNode(node.SYMLINK);
-    }
-  } catch (e) {
-    return callback(e);
-  }
-
-  if (!(node && typeof node === 'object' && node.SYMLINK == null)) {
-    return callback(new Error(filepath + ' is not a directory.'));
-  }
-
-  return callback(null, Object.keys(node));
-});
-
-fs.readFile.mockImplementation(function(filepath, encoding, callback) {
-  callback = asyncCallback(callback);
-  if (arguments.length === 2) {
-    callback = encoding;
-    encoding = null;
-  }
-
-  let node;
-  try {
-    node = getToNode(filepath);
-    // dir check
-    if (node && typeof node === 'object' && node.SYMLINK == null) {
-      callback(new Error('Error readFile a dir: ' + filepath));
-    }
-    if (node == null) {
-      return callback(Error('No such file: ' + filepath));
-    } else {
-      return callback(null, node);
-    }
-  } catch (e) {
-    return callback(e);
-  }
-});
-
-fs.readFileSync.mockImplementation(function(filepath, encoding) {
-  const node = getToNode(filepath);
-  // dir check
-  if (node && typeof node === 'object' && node.SYMLINK == null) {
-    throw new Error('Error readFileSync a dir: ' + filepath);
-  }
-  return node;
-});
-
-function makeStatResult(node) {
-  const isSymlink = node != null && node.SYMLINK != null;
-  return {
-    isBlockDevice: () => false,
-    isCharacterDevice: () => false,
-    isDirectory: () => node != null && typeof node === 'object' && !isSymlink,
-    isFIFO: () => false,
-    isFile: () => node != null && typeof node === 'string',
-    isSocket: () => false,
-    isSymbolicLink: () => isSymlink,
-    mtime,
-  };
-}
-
-function statSync(filepath) {
-  const node = getToNode(filepath);
-  if (node != null && node.SYMLINK) {
-    return statSync(node.SYMLINK);
-  }
-  return makeStatResult(node);
-}
-
-fs.stat.mockImplementation((filepath, callback) => {
-  callback = asyncCallback(callback);
-  let result;
-  try {
-    result = statSync(filepath);
-  } catch (e) {
-    callback(e);
-    return;
-  }
-  callback(null, result);
-});
-
-fs.statSync.mockImplementation(statSync);
-
-function lstatSync(filepath) {
-  const node = getToNode(filepath);
-  return makeStatResult(node);
-}
-
-fs.lstat.mockImplementation((filepath, callback) => {
-  callback = asyncCallback(callback);
-  let result;
-  try {
-    result = lstatSync(filepath);
-  } catch (e) {
-    callback(e);
-    return;
-  }
-  callback(null, result);
-});
-
-fs.lstatSync.mockImplementation(lstatSync);
-
-fs.open.mockImplementation(function(filepath) {
-  const callback = arguments[arguments.length - 1] || noop;
-  let data, error, fd;
-  try {
-    data = getToNode(filepath);
-  } catch (e) {
-    error = e;
-  }
-
-  if (error || data == null) {
-    error = Error(`ENOENT: no such file or directory, open ${filepath}`);
-  }
-  if (data != null) {
-    /* global Buffer: true */
-    fd = {buffer: new Buffer(data, 'utf8'), position: 0};
-  }
-
-  callback(error, fd);
-});
-
-fs.read.mockImplementation((fd, buffer, writeOffset, length, position, callback = noop) => {
-  let bytesWritten;
-  try {
-    if (position == null || position < 0) {
-      ({position} = fd);
-    }
-    bytesWritten = fd.buffer.copy(buffer, writeOffset, position, position + length);
-    fd.position = position + bytesWritten;
-  } catch (e) {
-    callback(Error('invalid argument'));
-    return;
-  }
-  callback(null, bytesWritten, buffer);
-});
-
-fs.close.mockImplementation((fd, callback = noop) => {
-  try {
-    fd.buffer = fs.position = undefined;
-  } catch (e) {
-    callback(Error('invalid argument'));
-    return;
-  }
-  callback(null);
-});
-
-let filesystem;
-
-fs.createReadStream.mockImplementation(filepath => {
-  if (!filepath.startsWith('/')) {
-    throw Error('Cannot open file ' + filepath);
-  }
-
-  const parts = filepath.split('/').slice(1);
-  let file = filesystem;
-
-  for (const part of parts) {
-    file = file[part];
-    if (!file) {
-      break;
-    }
-  }
-
-  if (typeof file !== 'string') {
-    throw Error('Cannot open file ' + filepath);
-  }
-
-  return new stream.Readable({
-    read() {
-      this.push(file, 'utf8');
-      this.push(null);
-    },
-  });
-});
-
-fs.createWriteStream.mockImplementation(file => {
-  let node;
-  try {
-    node = getToNode(dirname(file));
-  } finally {
-    if (typeof node === 'object') {
-      const writeStream = new stream.Writable({
-        write(chunk) {
-          this.__chunks.push(chunk);
-        },
-      });
-      writeStream.__file = file;
-      writeStream.__chunks = [];
-      writeStream.end = jest.fn(writeStream.end);
-      fs.createWriteStream.mock.returned.push(writeStream);
-      return writeStream;
-    } else {
-      throw new Error('Cannot open file ' + file);
-    }
-  }
-});
-fs.createWriteStream.mock.returned = [];
-
-fs.__setMockFilesystem = object => (filesystem = object);
-
-const watcherListByPath = new Map();
-
-fs.watch.mockImplementation((filename, options, listener) => {
-  if (options.recursive) {
-    throw new Error('recursive watch not implemented');
-  }
-  let watcherList = watcherListByPath.get(filename);
-  if (watcherList == null) {
-    watcherList = [];
-    watcherListByPath.set(filename, watcherList);
-  }
-  const fsWatcher = new EventEmitter();
-  fsWatcher.on('change', listener);
-  fsWatcher.close = () => {
-    watcherList.splice(watcherList.indexOf(fsWatcher), 1);
-    fsWatcher.close = () => { throw new Error('FSWatcher is already closed'); };
-  };
-  watcherList.push(fsWatcher);
-});
-
-fs.__triggerWatchEvent = (eventType, filename) => {
-  const directWatchers = watcherListByPath.get(filename) || [];
-  directWatchers.forEach(wtc => wtc.emit('change', eventType));
-  const dirPath = path.dirname(filename);
-  const dirWatchers = watcherListByPath.get(dirPath) || [];
-  dirWatchers.forEach(wtc => wtc.emit('change', eventType, path.relative(dirPath, filename)));
-};
-
-function getToNode(filepath) {
-  // Ignore the drive for Windows paths.
-  if (filepath.match(/^[a-zA-Z]:\\/)) {
-    filepath = filepath.substring(2);
-  }
-
-  if (filepath.endsWith(path.sep)) {
-    filepath = filepath.slice(0, -1);
-  }
-  const parts = filepath.split(/[\/\\]/);
-  if (parts[0] !== '') {
-    throw new Error('Make sure all paths are absolute.');
-  }
-  let node = filesystem;
-  parts.slice(1).forEach(part => {
-    if (node && node.SYMLINK) {
-      node = getToNode(node.SYMLINK);
-    }
-    node = node[part];
-    if (node == null) {
-      const err = new Error('ENOENT: no such file or directory');
-      err.code = 'ENOENT';
-      throw err;
-    }
-  });
-
-  return node;
-}
-
-module.exports = fs;
+module.exports = require('./fs');