Test lifecycle hooks (before, after) in Node.js - Mini Project: Build & Apply

Test lifecycle hooks (before, after) in Node.js

📖 Scenario: You are writing tests for a simple calculator module in Node.js. You want to prepare some setup before tests run and clean up after all tests finish.

🎯 Goal: Build a test file using before and after hooks to initialize and reset a variable around your tests.

📋 What You'll Learn

Create a variable counter initialized to 0

Use a before hook to set counter to 5 before tests

Write a test that checks counter equals 5

Use an after hook to reset counter to 0 after tests

💡 Why This Matters

🌍 Real World

Test lifecycle hooks help prepare and clean up resources like database connections or test data before and after tests run.

💼 Career

Understanding test hooks is essential for writing reliable automated tests in Node.js projects, a common skill in software development jobs.

1

DATA SETUP: Create a variable counter initialized to 0

Create a variable called counter and set it to 0.

Node.js

// Create a variable called counter and set it to 0
// Your code here

Need a hint?

Use let counter = 0; to create the variable.

2

CONFIGURATION: Add a before hook to set counter to 5

Add a before hook that sets counter to 5 before tests run.

Node.js

let counter = 0;

// Add a before hook to set counter to 5
// Your code here

Need a hint?

Use before(() => { counter = 5; }); to set up before tests.

3

CORE LOGIC: Write a test that checks counter equals 5

Write a test using it named 'counter should be 5' that asserts counter === 5 using strictEqual from assert.

Node.js

let counter = 0;

before(() => {
    counter = 5;
});

// Write a test named 'counter should be 5' that checks counter === 5
// Your code here

Need a hint?

Use it('counter should be 5', () => { assert.strictEqual(counter, 5); }); to write the test.

4

COMPLETION: Add an after hook to reset counter to 0

Add an after hook that resets counter to 0 after all tests run.

Node.js

import assert from 'assert';

let counter = 0;

before(() => {
    counter = 5;
});

it('counter should be 5', () => {
    assert.strictEqual(counter, 5);
});

// Add an after hook to reset counter to 0
// Your code here

Need a hint?

Use after(() => { counter = 0; }); to clean up after tests.