const db = require('../../src/persistence'); const getItems = require('../../src/routes/getItems'); const ITEMS = [{ id: 12345 }]; jest.mock('../../src/persistence', () => ({ getItems: jest.fn(), })); test('it gets items correctly', async () => { const req = {}; const res = { send: jest.fn() }; db.getItems.mockReturnValue(Promise.resolve(ITEMS)); await getItems(req, res); expect(db.getItems.mock.calls.length).toBe(1); expect(res.send.mock.calls[0].length).toBe(1); expect(res.send.mock.calls[0][0]).toEqual(ITEMS); });