Add dependency unification script

package.json

@@ -67,7 +67,8 @@
     "system-test": "npm run st -- --verbose system-test/**/*.test.js **/system-test/**/*.test.js",
     "system-cover": "npm run pretest && nyc --cache npm run system-test && nyc report --reporter=html",
     "all-test": "npm run st -- --no-power-assert bigquery/system-test/*.test.js test/**/*.test.js **/test/**/*.test.js system-test/**/*.test.js **/system-test/**/*.test.js",
-    "all-cover": "npm run pretest && nyc --cache npm run all-test && nyc report --reporter=html"
+    "all-cover": "npm run pretest && nyc --cache npm run all-test && nyc report --reporter=html",
+    "unify": "node scripts/unify"
   },
   "devDependencies": {
     "@google-cloud/bigquery": "0.6.0",

scripts/unify

@@ -0,0 +1,36 @@
+'use strict';
+
+// Copyright 2016, Google, Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+const fs = require(`fs`);
+const path = require(`path`);
+
+const PROJECT_ROOT = path.join(__dirname, `..`);
+
+// Get subdirectories with a `package.json` file
+const directories = fs.readdirSync(PROJECT_ROOT)
+                      .filter((dir) => fs.existsSync(path.join(PROJECT_ROOT, dir, `package.json`)));
+
+// Dedupe package.json dependencies
+// WARNING: This will fail if two different versions of the same package are required.
+const pkgSet = {};
+let pkgJson;
+directories.forEach((dir) => {
+  pkgJson = JSON.parse(fs.readFileSync(path.join(PROJECT_ROOT, dir, `package.json`)));
+  Object.assign(pkgSet, pkgJson.dependencies);
+});
+
+// Update root-level package.json (by shelling to npm)
+const spawn = require('child_process').spawn;
+spawn(`yarn`, [`add`].concat(Object.keys(pkgSet).map(pkg => `${pkg}@${pkgSet[pkg]}`)));