Initialize repository

.eslintrc

@@ -0,0 +1,19 @@
+{
+  "parserOptions": {
+    "ecmaVersion": 2017,
+    "ecmaFeatures": {
+      "experimentalObjectRestSpread": true
+    }
+  },
+  "plugins": [
+    "prettier"
+  ],
+  "rules": {
+    "prettier/prettier": ["error", {
+      "singleQuote": true,
+      "trailingComma": "all",
+      "bracketSpacing": false,
+      "jsxBracketSameLine": true
+    }]
+  }
+}

.gitignore

@@ -0,0 +1,4 @@
+node_modules
+npm-debug.log
+*.pem
+.env

.travis.yml

@@ -0,0 +1,12 @@
+dist: trusty
+sudo: false
+language: node_js
+node_js: 8.6.0
+before_install:
+  - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 1.2.0
+  - export PATH=$HOME/.yarn/bin:$PATH
+cache:
+  yarn: true
+before_install: yarn global add greenkeeper-lockfile@1
+before_script: greenkeeper-lockfile-update
+after_script: greenkeeper-lockfile-upload

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2017 Uber Technologies, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,15 @@
+# probot-app-pr-title
+
+> a GitHub App built with [probot](https://github.com/probot/probot) that enforces the format of PR titles/commits
+
+## Setup
+
+```
+# Install dependencies
+npm install
+
+# Run the bot
+npm start
+```
+
+See [docs/deploy.md](docs/deploy.md) if you would like to run your own instance of this app.

__tests__/validate-title.js

@@ -0,0 +1,44 @@
+const t = require('assert');
+
+const isValidTitle = require('../validate-title.js');
+
+test('valid commits pass', () => {
+  const valid = [
+    'Update subsystem X for readability',
+    'Refactor subsystem X for readability',
+    'Update getting started documentation',
+    'Remove deprecated methods',
+    'Release version 1.0.0',
+    'Merge pull request #123 from user/branch',
+    'Add tests for X',
+    'Delete thing',
+    'Revert whatever',
+  ];
+
+  valid.forEach(msg => {
+    t.equal(isValidTitle(msg), true);
+  });
+});
+
+test('invalid commits fail', () => {
+  const invalid = [
+    'Revert',
+    'fixed bug with Y',
+    'changing behavior of X',
+    'more fixes for broken stuff',
+    'sweet new API methods',
+    'UPDATE documentation',
+    'Add a cool thing!',
+    'I added tests for X',
+    'Adding tests for X',
+    'tea is good',
+    'bottle it up entirely',
+    'Add cool thing. Add another thing',
+    `potato doesn't work`,
+    'revert whatever',
+  ];
+
+  invalid.forEach(msg => {
+    t.equal(isValidTitle(msg), false);
+  });
+});

docs/deploy.md

@@ -0,0 +1,7 @@
+# Deploying
+
+If you would like to run your own instance of this app, see the [docs for deployment](https://probot.github.io/docs/deployment/).
+
+This app requires these **Permissions & events** for the GitHub App:
+
+> **TODO**: List permissions required for deployment here. See [probot/stale](https://github.com/probot/stale/blob/master/docs/deploy.md) for an example.

index.js

@@ -0,0 +1,33 @@
+const isValidTitle = require('./validate-title.js');
+
+module.exports = robot => {
+  robot.on('pull_request.opened', check);
+  robot.on('pull_request.edited', check);
+
+  async function check(context) {
+    const passed = isValidTitle(pr.title);
+    setStatus(context, passed);
+  }
+};
+
+function setStatus(context, passing) {
+  const {github} = context;
+
+  const status = passing
+    ? {
+        state: 'success',
+        description: 'PR title is valid',
+      }
+    : {
+        state: 'failure',
+        description: 'PR title is invalid',
+      };
+
+  github.repos.createStatus(
+    context.repo({
+      ...status,
+      sha: context.payload.pull_request.head.sha,
+      context: 'pr_title',
+    }),
+  );
+}

package.json

@@ -0,0 +1,29 @@
+{
+  "name": "probot-app-pr-title",
+  "version": "1.0.0",
+  "description": "GitHub App that enforces the format of PR titles/commits",
+  "author": "Ryan Tsao <[email protected]>",
+  "contributors": [],
+  "repository": "https://github.com/uber-web/probot-app-pr-title.git",
+  "scripts": {
+    "start": "probot run ./index.js",
+    "test": "npm run lint && jest",
+    "lint": "eslint .",
+    "fix": "eslint . --fix"
+  },
+  "dependencies": {
+    "compromise": "^10.7.2",
+    "probot": "^0.11.0"
+  },
+  "devDependencies": {
+    "eslint": "^4.8.0",
+    "eslint-plugin-prettier": "^2.3.1",
+    "jest": "^21.2.1",
+    "localtunnel": "^1.8.3",
+    "prettier": "^1.7.4"
+  },
+  "engines": {
+    "node": ">= 8.6.0"
+  },
+  "license": "MIT"
+}

validate-title.js

@@ -0,0 +1,60 @@
+const nlp = require('compromise');
+
+module.exports = function isValidTitle(text) {
+  const parsed = nlp(text);
+  return isValidSentence(parsed) && firstTermIsValidVerb(parsed);
+};
+
+// Validate text is a single sentence with no end punctuation
+function isValidSentence(parsed) {
+  const sentences = parsed.sentences();
+  // must be one and only one sentence
+  if (sentences.length !== 1) {
+    return false;
+  }
+  // must be at least two words long
+  if (parsed.terms().length < 2) {
+    return false;
+  }
+  // must not have any end punctuation
+  if (sentences.list[0].endPunctuation() !== null) {
+    return false;
+  }
+  return true;
+}
+
+// The following verbs starting with `re` are categorized as singular nouns
+// See: https://github.com/nlp-compromise/compromise/issues/412
+const nounWhitelist = new Set([
+  'refactor',
+  'release',
+  'revert',
+  'restore',
+  'recycle',
+  'repeat',
+  'rebuild',
+  'reconcile',
+  'record',
+  'redefine',
+  'recover',
+  'restructure',
+  'resolve',
+]);
+
+// Validate first word is a capitalized imperative mood verb
+function firstTermIsValidVerb(parsed) {
+  const term = parsed.terms().data()[0];
+  return isValidVerb(term) && isCapitalized(term);
+}
+
+function isValidVerb(term) {
+  return nounWhitelist.has(term.normal) || isInfinitiveVerb(term);
+}
+
+function isInfinitiveVerb(term) {
+  return term.tags.includes('Verb') && term.tags.includes('Infinitive');
+}
+
+function isCapitalized(term) {
+  return term.tags.includes('TitleCase');
+}