Add a way to diff the new tarball content with previously published v…

…ersion

This is intended to be used as part of our release process before publishing to NPM
--dry-run is a useful step, but can be fairly noisy, yarn run v1.21.1
to go along the fake deploy and more clearly shows what would be added and deleted

build/diff-tarball.js

@@ -0,0 +1,18 @@
+const packlist = require('npm-packlist')
+const npmContent = require('list-npm-contents');
+
+npmContent('mapbox-gl').then(function(last_version_files) {
+    packlist({ path: '.' }).then(function(new_version_files) {
+        new_version_files = new_version_files.map(file => file.replace(/\/\/+/g, '/'));
+        let diff_new = new_version_files.filter(x => !last_version_files.includes(x));
+        let diff_last = last_version_files.filter(x => !new_version_files.includes(x));
+        console.log(`${diff_new.length} files are about to be added in the new tarball`)
+        diff_new.forEach(file => {
+            console.log('+', file);
+        });
+        console.log(`${diff_last.length} files are about to be deleted in the new tarball`)
+        diff_last.forEach(file => {
+            console.log('-', file);
+        });
+    });
+});

package.json

@@ -73,11 +73,13 @@
     "jsdom": "^13.0.0",
     "json-stringify-pretty-compact": "^2.0.0",
     "jsonwebtoken": "^8.3.0",
+    "list-npm-contents": "^1.0.2",
     "lodash.template": "^4.5.0",
     "mapbox-gl-styles": "^2.0.2",
     "mock-geolocation": "^1.0.11",
     "node-notifier": "^5.4.3",
     "npm-font-open-sans": "^1.1.0",
+    "npm-packlist": "^2.1.1",
     "npm-run-all": "^4.1.5",
     "nyc": "^13.3.0",
     "pirates": "^4.0.1",
@@ -138,6 +140,7 @@
     "start-tests": "run-p build-token watch-css watch-query start-server",
     "start-bench": "run-p build-token watch-benchmarks start-server",
     "start-release": "run-s build-token build-prod-min build-css print-release-url start-server",
+    "diff-tarball": "build/run-node build/diff-tarball",
     "lint": "eslint --cache --ignore-path .gitignore src test bench debug/*.html",
     "lint-docs": "documentation lint src/index.js",
     "lint-css": "stylelint 'src/css/mapbox-gl.css'",