diff --git a/packages/metro/src/AssetServer/index.js b/packages/metro/src/AssetServer/index.js
index ecf34885..5cf28043 100644
--- a/packages/metro/src/AssetServer/index.js
+++ b/packages/metro/src/AssetServer/index.js
@@ -22,8 +22,7 @@ const path = require('path');
 const toLocalPath = require('../node-haste/lib/toLocalPath');
 
 const {isAssetTypeAnImage} = require('../Bundler/util');
-
-import type {AssetPath} from '../node-haste/lib/AssetPaths';
+const {findRoot, getAbsoluteAssetRecord, hashFiles} = require('./util');
 
 type AssetInfo = {|
   files: Array<string>,
@@ -46,10 +45,7 @@ export type AssetData = {|
   type: string,
 |};
 
-const stat = denodeify(fs.stat);
-const readDir = denodeify(fs.readdir);
 const readFile = denodeify(fs.readFile);
-const hashFiles = denodeify(hashFilesCb);
 
 class AssetServer {
   _roots: $ReadOnlyArray<string>;
@@ -160,149 +156,13 @@ class AssetServer {
     files: Array<string>,
     scales: Array<number>,
   |}> {
-    const filename = path.basename(assetPath);
+    const dir = await findRoot(this._roots, path.dirname(assetPath), assetPath);
 
-    const dir = await this._findRoot(
-      this._roots,
-      path.dirname(assetPath),
-      assetPath,
-    );
-
-    const files = await readDir(dir);
-
-    const assetData = AssetPaths.parse(
-      filename,
-      new Set(platform != null ? [platform] : []),
-    );
-
-    const map = this._buildAssetMap(dir, files, platform);
-
-    let record;
-    if (platform != null) {
-      record =
-        map.get(getAssetKey(assetData.assetName, platform)) ||
-        map.get(assetData.assetName);
-    } else {
-      record = map.get(assetData.assetName);
-    }
-
-    if (!record) {
-      throw new Error(
-        /* $FlowFixMe: platform can be null */
-        `Asset not found: ${assetPath} for platform: ${platform}`,
-      );
-    }
-
-    return record;
-  }
-
-  async _findRoot(
-    roots: $ReadOnlyArray<string>,
-    dir: string,
-    debugInfoFile: string,
-  ): Promise<string> {
-    const stats = await Promise.all(
-      roots.map(async root => {
-        // important: we want to resolve root + dir
-        // to ensure the requested path doesn't traverse beyond root
-        const absPath = path.resolve(root, dir);
-
-        try {
-          const fstat = await stat(absPath);
-
-          // keep asset requests from traversing files
-          // up from the root (e.g. ../../../etc/hosts)
-          if (!absPath.startsWith(path.resolve(root))) {
-            return {path: absPath, isValid: false};
-          }
-          return {path: absPath, isValid: fstat.isDirectory()};
-        } catch (_) {
-          return {path: absPath, isValid: false};
-        }
-      }),
-    );
-
-    for (let i = 0; i < stats.length; i++) {
-      if (stats[i].isValid) {
-        return stats[i].path;
-      }
-    }
-
-    const rootsString = roots.map(s => `'${s}'`).join(', ');
-    throw new Error(
-      `'${debugInfoFile}' could not be found, because '${dir}' is not a ` +
-        `subdirectory of any of the roots  (${rootsString})`,
+    return await getAbsoluteAssetRecord(
+      path.join(dir, path.basename(assetPath)),
+      platform,
     );
   }
-
-  _buildAssetMap(
-    dir: string,
-    files: $ReadOnlyArray<string>,
-    platform: ?string,
-  ): Map<
-    string,
-    {|
-      files: Array<string>,
-      scales: Array<number>,
-    |},
-  > {
-    const platforms = new Set(platform != null ? [platform] : []);
-    const assets = files.map(this._getAssetDataFromName.bind(this, platforms));
-    const map = new Map();
-    assets.forEach(function(asset, i) {
-      if (asset == null) {
-        return;
-      }
-      const file = files[i];
-      const assetKey = getAssetKey(asset.assetName, asset.platform);
-      let record = map.get(assetKey);
-      if (!record) {
-        record = {
-          scales: [],
-          files: [],
-        };
-        map.set(assetKey, record);
-      }
-
-      let insertIndex;
-      const length = record.scales.length;
-
-      for (insertIndex = 0; insertIndex < length; insertIndex++) {
-        if (asset.resolution < record.scales[insertIndex]) {
-          break;
-        }
-      }
-      record.scales.splice(insertIndex, 0, asset.resolution);
-      record.files.splice(insertIndex, 0, path.join(dir, file));
-    });
-
-    return map;
-  }
-
-  _getAssetDataFromName(platforms: Set<string>, file: string): ?AssetPath {
-    return AssetPaths.tryParse(file, platforms);
-  }
-}
-
-function getAssetKey(assetName, platform) {
-  if (platform != null) {
-    return `${assetName} : ${platform}`;
-  } else {
-    return assetName;
-  }
-}
-
-function hashFilesCb(files, hash, callback) {
-  if (!files.length) {
-    callback(null);
-    return;
-  }
-
-  fs
-    .createReadStream(files.shift())
-    .on('data', data => hash.update(data))
-    .once('end', () => hashFiles(files, hash, callback))
-    .once('error', error => callback(error));
 }
 
 module.exports = AssetServer;
diff --git a/packages/metro/src/AssetServer/util.js b/packages/metro/src/AssetServer/util.js
new file mode 100644
index 00000000..7590332f
--- /dev/null
+++ b/packages/metro/src/AssetServer/util.js
@@ -0,0 +1,178 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ * @format
+ */
+
+'use strict';
+
+const AssetPaths = require('../node-haste/lib/AssetPaths');
+
+const denodeify = require('denodeify');
+const fs = require('fs');
+const path = require('path');
+
+const stat = denodeify(fs.stat);
+const readDir = denodeify(fs.readdir);
+
+import type {AssetPath} from '../node-haste/lib/AssetPaths';
+
+function buildAssetMap(
+  dir: string,
+  files: $ReadOnlyArray<string>,
+  platform: ?string,
+): Map<
+  string,
+  {|
+    files: Array<string>,
+    scales: Array<number>,
+  |},
+> {
+  const platforms = new Set(platform != null ? [platform] : []);
+  const assets = files.map(getAssetDataFromName.bind(this, platforms));
+  const map = new Map();
+  assets.forEach(function(asset, i) {
+    if (asset == null) {
+      return;
+    }
+    const file = files[i];
+    const assetKey = getAssetKey(asset.assetName, asset.platform);
+    let record = map.get(assetKey);
+    if (!record) {
+      record = {
+        scales: [],
+        files: [],
+      };
+      map.set(assetKey, record);
+    }
+
+    let insertIndex;
+    const length = record.scales.length;
+
+    for (insertIndex = 0; insertIndex < length; insertIndex++) {
+      if (asset.resolution < record.scales[insertIndex]) {
+        break;
+      }
+    }
+    record.scales.splice(insertIndex, 0, asset.resolution);
+    record.files.splice(insertIndex, 0, path.join(dir, file));
+  });
+
+  return map;
+}
+
+function getAssetDataFromName(
+  platforms: Set<string>,
+  file: string,
+): ?AssetPath {
+  return AssetPaths.tryParse(file, platforms);
+}
+
+function getAssetKey(assetName, platform) {
+  if (platform != null) {
+    return `${assetName} : ${platform}`;
+  } else {
+    return assetName;
+  }
+}
+
+function hashFiles(files, hash, callback) {
+  if (!files.length) {
+    callback(null);
+    return;
+  }
+
+  fs
+    .createReadStream(files.shift())
+    .on('data', data => hash.update(data))
+    .once('end', () => hashFiles(files, hash, callback))
+    .once('error', error => callback(error));
+}
+
+async function getAbsoluteAssetRecord(
+  assetPath: string,
+  platform: ?string = null,
+): Promise<{|
+  files: Array<string>,
+  scales: Array<number>,
+|}> {
+  const filename = path.basename(assetPath);
+  const dir = path.dirname(assetPath);
+  const files = await readDir(dir);
+
+  const assetData = AssetPaths.parse(
+    filename,
+    new Set(platform != null ? [platform] : []),
+  );
+
+  const map = buildAssetMap(dir, files, platform);
+
+  let record;
+  if (platform != null) {
+    record =
+      map.get(getAssetKey(assetData.assetName, platform)) ||
+      map.get(assetData.assetName);
+  } else {
+    record = map.get(assetData.assetName);
+  }
+
+  if (!record) {
+    throw new Error(
+      /* $FlowFixMe: platform can be null */
+      `Asset not found: ${assetPath} for platform: ${platform}`,
+    );
+  }
+
+  return record;
+}
+
+async function findRoot(
+  roots: $ReadOnlyArray<string>,
+  dir: string,
+  debugInfoFile: string,
+): Promise<string> {
+  const stats = await Promise.all(
+    roots.map(async root => {
+      // important: we want to resolve root + dir
+      // to ensure the requested path doesn't traverse beyond root
+      const absPath = path.resolve(root, dir);
+
+      try {
+        const fstat = await stat(absPath);
+
+        // keep asset requests from traversing files
+        // up from the root (e.g. ../../../etc/hosts)
+        if (!absPath.startsWith(path.resolve(root))) {
+          return {path: absPath, isValid: false};
+        }
+        return {path: absPath, isValid: fstat.isDirectory()};
+      } catch (_) {
+        return {path: absPath, isValid: false};
+      }
+    }),
+  );
+
+  for (let i = 0; i < stats.length; i++) {
+    if (stats[i].isValid) {
+      return stats[i].path;
+    }
+  }
+
+  const rootsString = roots.map(s => `'${s}'`).join(', ');
+  throw new Error(
+    `'${debugInfoFile}' could not be found, because '${dir}' is not a ` +
+      `subdirectory of any of the roots  (${rootsString})`,
+  );
+}
+
+module.exports = {
+  findRoot,
+  getAbsoluteAssetRecord,
+  hashFiles: denodeify(hashFiles),
+};