fix(ci): use github API to patch CI env

.circleci/config.yml

@@ -43,6 +43,10 @@ common_settings:
       - venia-concept/node_modules
     key: 'v1-npm-cache-{{ .Branch }}'
 
+  patch_environment_for_pr: &patch_environment_for_pr
+    name: Patch CircleCI environment to help detect pull requests
+    command: node .circleci/patch_circleci_environment.js >> $BASH_ENV
+
   # Greenkeeper Lockfile wants to use the latest lockfile format at all times,
   # and therefore the latest NPM at all times.
   install_latest_npm: &install_latest_npm
@@ -70,7 +74,6 @@ common_settings:
   test_result_path: &test_result_path
     path: "test-results"
 
-
   coveralls: &coveralls
     name: Coveralls Coverage Analysis
     command: npm run coveralls

.circleci/patch_circleci_environment.js

@@ -0,0 +1,67 @@
+(async env => {
+    const url = require('url');
+    const qs = require('querystring');
+    const fetch = require('node-fetch');
+
+    const repo = process.env.CIRCLE_PROJECT_REPONAME;
+    const owner = process.env.CIRCLE_PROJECT_USERNAME;
+    const branch = process.env.CIRCLE_BRANCH;
+    const token = process.env.GH_TOKEN;
+
+    const query = `query getPR($owner: String!, $name: String!, $ref: String!) {
+        repository(owner: $owner, name: $name) {
+          ref(qualifiedName: $ref) {
+            associatedPullRequests(last: 1) {
+              nodes {
+                url
+                number
+              }
+            }
+          }
+        }
+      }
+      `;
+
+    const response = await fetch('https://api.github.com/graphql', {
+        method: 'POST',
+        credentials: 'include',
+        headers: {
+            Authorization: `bearer ${token}`
+        },
+        body: JSON.stringify({
+            query,
+            variables: {
+                owner,
+                name: repo,
+                ref: `/refs/heads/${branch}`
+            }
+        })
+    });
+
+    const responseBody = await response.text();
+
+    try {
+        const prs = JSON.parse(responseBody).data.repository.ref
+            .associatedPullRequests.nodes;
+        if (prs.length === 0) {
+            const { url, number } = prs[0];
+            return `
+CI_PULL_REQUEST="${url}"
+CI_PULL_REQUESTS="${url}"
+CIRCLE_PULL_REQUEST="${url}"
+CIRCLE_PULL_REQUESTS="${url}"
+CIRCLE_PR_NUMBER="${number}"
+`;
+        }
+    } catch (e) {
+        throw new Error(responseBody);
+    }
+})(process).then(
+    out => {
+        console.log(out);
+    },
+    e => {
+        console.error('Failed to retrieve pull request from GitHub', e);
+        process.exit(1);
+    }
+);

package.json

@@ -59,6 +59,7 @@
     "junit-report-builder": "^1.3.1",
     "lerna": "^3.0.0-beta.21",
     "mkdirp": "^0.5.1",
+    "node-fetch": "^2.2.0",
     "nodemon": "^1.18.3",
     "prettier": "^1.13.5",
     "prettier-check": "^2.0.0",