Adds danger_js with an initial rule for warning about large PRs

Signed-off-by: Anandaroop Roy <roop@artsymail.com>

Author: Orta Therox

dangerfile.js

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2013-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.
+ */
+
+'use strict';
+
+const { danger, markdown, warn } = require('danger');
+
+// Tags big PRs
+var bigPRThreshold = 600;
+if (danger.git.modified_files + danger.git.added_files + danger.git.deleted_files > bigPRThreshold) {
+  const title = ':exclamation: Big PR';
+  const files = danger.git.modified_files + danger.git.added_files + danger.git.deleted_files;
+  const idea = `This PR is extremely unlikely to get reviewed because it touches ${files} files.`;
+  warn(`${title} - <i>${idea}</i>`);
+
+  markdown('@facebook-github-bot large-pr');  
+}

package.json

@@ -47,6 +47,7 @@
     "coveralls": "^2.11.6",
     "create-react-class": "^15.6.2",
     "cross-env": "^5.1.1",
+    "danger": "^2.1.5",
     "del": "^2.0.2",
     "derequire": "^2.0.3",
     "escape-string-regexp": "^1.0.5",

scripts/circleci/test_entry_point.sh

@@ -24,6 +24,7 @@ fi
 if [ $((2 % CIRCLE_NODE_TOTAL)) -eq "$CIRCLE_NODE_INDEX" ]; then
   COMMANDS_TO_RUN+=('./scripts/circleci/build.sh')
   COMMANDS_TO_RUN+=('yarn test-build --runInBand')
+  COMMANDS_TO_RUN+=('node ./scripts/tasks/danger')
   COMMANDS_TO_RUN+=('yarn test-build-prod --runInBand')
   COMMANDS_TO_RUN+=('./scripts/circleci/upload_build.sh')
 fi

scripts/tasks/danger.js

@@ -0,0 +1,32 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+var path = require('path');
+var spawn = require('child_process').spawn;
+
+var extension = process.platform === 'win32' ? '.cmd' : '';
+
+// This came from React Native's circle.yaml
+const token = 'e622517d9f1136ea8900' + '07c6373666312cdfaa69';
+spawn(path.join('node_modules', '.bin', 'danger' + extension), [], {
+  // Allow colors to pass through
+  stdio: 'inherit',
+  env: {
+    ...process.env, 
+    DANGER_GITHUB_API_TOKEN: token,
+  },
+}).on('close', function(code) {
+  if (code !== 0) {
+    console.error('Danger failed');
+  } else {
+    console.log('Danger passed');
+  }
+
+  process.exit(code);
+});