add modularity integration test

js/tests/integration/rollup.bundle-modularity.js

@@ -0,0 +1,17 @@
+/* eslint-env node */
+
+const commonjs = require('rollup-plugin-commonjs')
+const configRollup = require('./rollup.bundle')
+
+const config = {
+  ...configRollup,
+  input: 'js/tests/integration/bundle-modularity.js',
+  output: {
+    file: 'js/coverage/bundle-modularity.js',
+    format: 'iife'
+  }
+}
+
+config.plugins.unshift(commonjs())
+
+module.exports = config