Improve linting

.eslintrc

@@ -1,10 +1,15 @@
 {
+  "extends": "eslint:recommended",
   "parserOptions": {
     "ecmaVersion": 2017,
     "ecmaFeatures": {
       "experimentalObjectRestSpread": true
     }
   },
+  "env": {
+    "node": true,
+    "es6": true
+  },
   "plugins": [
     "prettier"
   ],

__tests__/index.js

@@ -4,6 +4,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/* eslint-env jest */
+
 const t = require('assert');
 
 test('dummy test', () => {

index.js

@@ -13,17 +13,26 @@ module.exports = robot => {
   async function check(context) {
     const {github} = context;
     const pr = context.payload.pull_request;
-    const issues = pr.body.match(issueRegex());
-    const status =
-      issues === null
-        ? {
-            state: 'failure',
-            description: 'PR does not reference an issue',
-          }
-        : {
-            state: 'success',
-            description: 'PR references an issue',
-          };
+
+    function hasIssue() {
+      const issues = pr.body.match(issueRegex());
+      if (issues !== null) {
+        return true;
+      }
+      const repo = context.payload.repository.full_name;
+      const urlRegex = new RegExp(`${repo}/issues/\\d+`, 'g');
+      return pr.body.match(urlRegex) !== null;
+    }
+
+    const status = hasIssue()
+      ? {
+          state: 'success',
+          description: 'PR references an issue',
+        }
+      : {
+          state: 'failure',
+          description: 'PR does not reference an issue',
+        };
 
     setStatus(status);
 

package.json

@@ -13,7 +13,7 @@
   },
   "dependencies": {
     "issue-regex": "^1.0.0",
-    "probot": "^0.11.0"
+    "probot": "^3.0.0"
   },
   "devDependencies": {
     "eslint": "^4.8.0",