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Use when writing or configuring Vitest tests - assertions, mocking, coverage, and workspace-aware testing for TypeScript projects
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| name | vitest |
| description | Use when writing or configuring Vitest tests - assertions, mocking, coverage, and workspace-aware testing for TypeScript projects |
import { describe, it, expect, vi, beforeEach } from 'vitest';
describe('Calculator', () => {
beforeEach(() => {
vi.clearAllMocks();
});
it('adds numbers correctly', () => {
expect(add(2, 3)).toBe(5);
});
it('handles async operations', async () => {
const result = await fetchData();
expect(result).toMatchObject({ id: 1 });
});
it('mocks dependencies', () => {
const mockFn = vi.fn().mockReturnValue(42);
expect(mockFn()).toBe(42);
expect(mockFn).toHaveBeenCalledOnce();
});
});
| Assertion | Purpose |
|---|---|
toBe(value) | Strict equality (===) |
toEqual(value) | Deep equality |
toMatchObject(obj) | Partial object match |
toContain(item) | Array/string contains |
toThrow(error?) | Function throws |
toMatchSnapshot() | Snapshot testing |
toHaveBeenCalledWith() | Mock call verification |
// Mock module
vi.mock('./api', () => ({ fetchUser: vi.fn() }));
// Spy on method
const spy = vi.spyOn(object, 'method');
// Mock implementation
mockFn.mockImplementation((x) => x * 2);
mockFn.mockResolvedValue({ data: [] });
mockFn.mockRejectedValue(new Error('fail'));
import { defineConfig } from 'vitest/config';
export default defineConfig({
test: {
globals: true,
environment: 'node',
include: ['**/*.test.ts'],
coverage: { provider: 'v8', reporter: ['text', 'html'] }
}
});
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