[build] Add build that verifies the submodule pin is up-to-date

circle.yml

@@ -4,6 +4,7 @@ workflows:
   version: 2
   default:
     jobs:
+      - nitpick
       - clang-tidy:
           filters:
             branches:
@@ -217,6 +218,31 @@ step-library:
         destination: render-tests
 
 jobs:
+  nitpick:
+    docker:
+      - image: mbgl/7d2403f42e:base
+    working_directory: /src
+    environment:
+      LIBSYSCONFCPUS: 4
+      JOBS: 4
+      BUILDTYPE: Debug
+    steps:
+      - checkout
+      - *generate-cache-key
+      - *restore-cache
+      - run:
+          name: Initialize submodule
+          command: git submodule update --init mapbox-gl-js
+      - run:
+          name: npm install
+          command: npm install --ignore-scripts
+      - *save-cache
+      - run:
+          name: Verify submodule pin
+          command: scripts/nitpick/submodule-pin.js
+          when: always
+
+
 # ------------------------------------------------------------------------------
   clang-tidy:
     docker:

scripts/nitpick/index.js

@@ -0,0 +1,28 @@
+var failed = false;
+
+process.on('exit', function() {
+    if (failed) {
+        process.exitCode = 1;
+    }
+});
+
+module.exports = function(status, str, desc) {
+    if (status) {
+        console.warn(`\x1b[1m\x1b[32m✔︎ ${str}\x1b[0m`);
+    } else {
+        console.warn(`\x1b[1m\x1b[31m✘ ${str}\x1b[0m`);
+        failed = true;
+    }
+
+    if (desc) {
+        console.warn(`${desc.split('\n').map((line) => '|   ' + line).join('\n')}\n`);
+    }
+};
+
+module.exports.ok = function(str, desc) {
+    module.exports(true, str, desc);
+};
+
+module.exports.fail = function(str, desc) {
+    module.exports(false, str, desc);
+};

scripts/nitpick/submodule-pin.js

@@ -0,0 +1,13 @@
+#!/usr/bin/env node
+const nitpick = require('.');
+const child_process = require('child_process');
+
+// Make sure that the mapbox-gl-js submodule pin is up to date
+const head = child_process.execSync('git -C mapbox-gl-js rev-parse HEAD').toString().trim();
+const revs = child_process.execSync(`git -C mapbox-gl-js branch -a --contains ${head}`).toString().split('\n');
+
+if (revs.indexOf('  remotes/origin/master') >= 0) {
+    nitpick.ok(`mapbox-gl-js submodule pin is merged to master`);
+} else {
+    nitpick.fail(`mapbox-gl-js submodule is pinned to ${head}, which isn't merged to master`);
+}