automocking not working?

[cayter]

Hi guys, I'm trying to migrate my Jest tests over to Vitest, but somehow bumped into an issue where the mocked instance isn't being used in the actual code which leads to the expect().toBeCalledWith() failure. Is there any configuration I'm missing out? Thanks.

https://stackblitz.com/edit/vitest-dev-vitest-rmsdsh?file=src/getTodos.spec.js

Note: The above is an example from here.

[cayter]

@sheremet-va Any idea why the example on the doc doesn't work? Is that expected?

[cayter]

Thanks to @sheremet-va for the help on Discord and realised the main reason I wasn't able to get it working was due to I assumed Vitest's automocking works exactly the same as Jest but I was wrong.

At this point of time, when automock a class with Vitest, it doesn't automock the class prototype which we will need to do it manually.

Actual Code

handler.js

export function success(data) {}
export function failure(data) {}

getTodos.js

import { failure, success } from './handler.js';
import { Client } from 'pg';

export default async (event, context) => {
  const client = new Client({});

  await client.connect();

  try {
    const result = await client.query('SELECT * FROM todos;');
    client.end();

    return success({
      message: `${result.rowCount} item(s) returned`,
      data: result.rows,
      status: true,
    });
  } catch (e) {
    client.end();

    return failure({ message: e, status: false });
  }
};

Test Code

Jest

import { Client } from 'pg';
import getTodos from './getTodos.js';

jest.mock('pg');
jest.mock('./handler.js');

describe('get a list of todo items', () => {
  afterEach(() => {
    jest.clearAllMocks();
  });

  it('should return items successfully', async () => {
    await getTodos();

    expect(Client.prototype.connect).toHaveBeenCalledTimes(1);
    expect(Client.prototype.query).toHaveBeenCalledWith('SELECT * FROM todos;');
    expect(Client.prototype.end).toHaveBeenCalledTimes(2);
  });
});

Vitest

import { afterEach, describe, expect, it, vi } from 'vitest';
import { Client } from 'pg';
import getTodos from './getTodos.js';

vi.mock('pg', () => {
  const Client = vi.fn();
  Client.prototype.connect = vi.fn();
  Client.prototype.end = vi.fn();
  Client.prototype.query = vi.fn();

  return { Client };
});

vi.mock('./handler.js', () => {
  return {
    success: vi.fn(),
    failure: vi.fn(),
  };
});

describe('get a list of todo items', () => {
  afterEach(() => {
    vi.clearAllMocks();
  });

  it('should return items successfully', async () => {
    await getTodos();

    expect(Client.prototype.connect).toBeCalledTimes(1);
    expect(Client.prototype.query).toBeCalledWith('SELECT * FROM todos;');
    expect(Client.prototype.end).toBeCalledTimes(2);
  });
});