knex-mock-client

import { createTracker, MockClient } from 'knex-mock-client'; import { knex } from 'knex'; // Peer dependency // Imagine this is your actual DB setup file that gets mocked const db = knex({ client: MockClient }); // A function that uses the knex instance async function getUsersOlderThan(age: number) { return db('users').where('age', '>', age).select(); } describe('User Service', () => { let tracker: ReturnType<typeof createTracker>; beforeEach(() => { tracker = createTracker(db); // Initialize a new tracker before each test }); afterEach(() => { tracker.reset(); // Clear all mock handlers and query history after each test }); it('should retrieve users older than a given age', async () => { const mockUsers = [ { id: 1, name: 'Alice', age: 30 }, { id: 2, name: 'Bob', age: 35 } ]; // Configure the tracker to respond to a specific query tracker.on.select('users').response(mockUsers); const users = await getUsersOlderThan(25); expect(users).toEqual(mockUsers); // Verify the query that was executed const selectHistory = tracker.history.select; expect(selectHistory).toHaveLength(1); expect(selectHistory[0].method).toEqual('select'); expect(selectHistory[0].sql).toContain('select * from `users` where `age` > ?'); expect(selectHistory[0].bindings).toEqual([25]); }); it('should handle no users found', async () => { tracker.on.select('users').responseOnce([]); const users = await getUsersOlderThan(40); expect(users).toEqual([]); expect(tracker.history.select).toHaveLength(1); }); });