vitest

import { defineConfig } from 'vitest/config'; import { describe, it, expect, vi } from 'vitest'; // vitest.config.ts export default defineConfig({ test: { environment: 'jsdom', // or 'node', 'happy-dom' globals: true, setupFiles: ['./vitest.setup.ts'], }, }); // vitest.setup.ts (optional) // This file runs before all tests console.log('Vitest setup running...'); // my-utils.ts export const sum = (a: number, b: number) => a + b; export const fetchData = async () => { // In a real app, this would fetch data return Promise.resolve({ data: 'Hello Vitest' }); }; // my-utils.test.ts describe('my-utils', () => { it('sums two numbers', () => { expect(sum(1, 2)).toBe(3); }); it('fetches data correctly', async () => { // Mock fetchData to avoid actual network requests vi.spyOn(global, 'fetch').mockResolvedValue({ json: () => Promise.resolve({ data: 'Mocked Data' }) } as any); const result = await fetchData(); expect(result).toEqual({ data: 'Hello Vitest' }); // Note: Still testing fetchData's *internal* mock of fetch, not the actual global fetch. expect(vi.spyOn(global, 'fetch')).toHaveBeenCalledTimes(0); // My specific example of fetchData doesn't use global.fetch directly. // If fetchData *did* use global.fetch, the above spyOn would work. // For this specific example, let's mock the module itself for simplicity. vi.restoreAllMocks(); const mockFetch = vi.fn().mockResolvedValue({ data: 'Mocked Data' }); vi.mock('./my-utils', () => ({ fetchData: mockFetch })); const { fetchData: mockedFetchData } = await import('./my-utils'); const data = await mockedFetchData(); expect(data).toEqual({ data: 'Mocked Data' }); expect(mockFetch).toHaveBeenCalled(); }); it('creates snapshots', () => { const user = { id: 1, name: 'Vitest User' }; expect(user).toMatchSnapshot(); }); });