Added a mock DatabaseConnectionPool object for testing

lib/__mocks__/DatabaseConnectionPool.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const DatabaseConnectionPool = require('./DatabaseConnectionPool');
+
+const mockRunQuery = jest.fn((sql, params) => {
+	if (sql.slice(-1) !== ';')
+		throw new Error('Invalid query, needs ;');
+
+	// Execute as non-prepared if no params are supplied
+	if (typeof params === 'undefined') {
+		return {
+			sql: sql
+		};
+	}
+
+	return {
+		sql: sql,
+		params: params
+	};
+});
+
+jest.mock('./DatabaseConnectionPool', () => {
+	return jest.fn().mockImplementation(() => {
+		return { runQuery: mockRunQuery };
+	});
+});
+
+module.exports = DatabaseConnectionPool;