Add comprehensive tests for role middleware and fix package dependencies

node_modules/mysql2/lib/pool.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const BasePool = require('./base/pool.js');
+
+class Pool extends BasePool {
+  promise(promiseImpl) {
+    const PromisePool = require('./promise/pool.js');
+    return new PromisePool(this, promiseImpl);
+  }
+}
+
+module.exports = Pool;