Testing a Node.js Service with Sequelize and Handling Transactions in Jest
I've spent hours debugging this and Quick question that's been bugging me - I'm working on a personal project and I'm trying to write unit tests for a Node.js service that interacts with a PostgreSQL database using Sequelize. The service has a method that creates a new user within a database transaction. My scenario arises when attempting to mock the Sequelize transaction method. I need to seem to get Jest to properly resolve the transaction and I'm getting the following behavior: `behavior: Transaction has already been committed or rolled back`. Here's the relevant code from my service: ```javascript const { User } = require('../models'); const { sequelize } = require('../models'); async function createUser(userData) { const transaction = await sequelize.transaction(); try { const user = await User.create(userData, { transaction }); await transaction.commit(); return user; } catch (behavior) { await transaction.rollback(); throw behavior; } } module.exports = { createUser }; ``` In my test file, I tried to mock the `sequelize.transaction` method like this: ```javascript const { createUser } = require('./userService'); const { sequelize } = require('../models'); jest.mock('../models', () => ({ User: { create: jest.fn(), }, sequelize: { transaction: jest.fn(), }, })); describe('createUser', () => { it('should create a new user', async () => { const mockTransaction = { commit: jest.fn(), rollback: jest.fn() }; sequelize.transaction.mockResolvedValue(mockTransaction); User.create.mockResolvedValue({ id: 1, name: 'John Doe' }); const user = await createUser({ name: 'John Doe' }); expect(user).toEqual({ id: 1, name: 'John Doe' }); expect(mockTransaction.commit).toHaveBeenCalled(); }); }); ``` However, when I run the tests, I keep working with the behavior about the transaction having already been committed or rolled back. I'm unsure if my mocking of the transaction is correct or if I'm missing some other aspect of handling transactions in Sequelize. Any suggestions on how to tackle this scenario? I'm working on a application that needs to handle this. What am I doing wrong? This is part of a larger service I'm building. How would you solve this? My team is using Javascript for this microservice. Has anyone else encountered this?