Test Structure & Basics in Jest
From the Jest cheat sheet · Basic Testing · verified Jul 2026
Test Structure & Basics
Organizing tests with describe, it, and test blocks
javascript
// Basic test structure
describe('Calculator', () => {
test('adds 1 + 2 to equal 3', () => {
expect(1 + 2).toBe(3)
})
it('subtracts 5 - 2 to equal 3', () => {
expect(5 - 2).toBe(3)
})
})
// Setup and teardown
describe('User Service', () => {
let service
beforeEach(() => {
service = new UserService()
})
afterEach(() => {
service.cleanup()
})
beforeAll(async () => {
await database.connect()
})
afterAll(async () => {
await database.disconnect()
})
})💡 Use describe blocks to group related tests logically
⚡ beforeEach/afterEach run for every test, beforeAll/afterAll run once
📌 test and it are aliases - use whichever reads better
🟢 Use test.only to focus on a single test during development
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