Integration testing patterns in Node.js - Mini Project: Build & Apply

Integration Testing Patterns in Node.js

📖 Scenario: You are building a simple Node.js service that manages a list of users. You want to write integration tests to check how different parts of your service work together.

🎯 Goal: Build a basic integration test setup using Node.js and a testing framework. You will create a simple user data array, configure a test helper, write a test that checks user retrieval, and complete the test file with proper exports.

📋 What You'll Learn

Create an array called users with three user objects with exact names and ids

Add a helper variable called testUserId with the value 2

Write a function called getUserById that returns a user object by matching id

Export the getUserById function and users array for testing

💡 Why This Matters

🌍 Real World

Integration testing is used to check how different parts of a Node.js application work together, such as data retrieval and business logic.

💼 Career

Understanding integration testing patterns is essential for backend developers to ensure their services behave correctly when components interact.

1

DATA SETUP: Create the user data array

Create an array called users with these exact user objects: { id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }, and { id: 3, name: 'Charlie' }.

Node.js

// Create the users array with three user objects
// Your code here

Need a hint?

Use const users = [ ... ] and include the exact objects inside the array.

2

CONFIGURATION: Add a test user ID variable

Add a constant variable called testUserId and set it to the number 2.

Node.js

const users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' },
  { id: 3, name: 'Charlie' }
];

// Add testUserId variable below
// Your code here

Need a hint?

Use const testUserId = 2; to create the variable.

3

CORE LOGIC: Write a function to get user by ID

Write a function called getUserById that takes an id parameter and returns the user object from users where user.id === id.

Node.js

const users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' },
  { id: 3, name: 'Charlie' }
];

const testUserId = 2;

// Write getUserById function below
// Your code here

Need a hint?

Use users.find() to locate the user with matching id.

4

COMPLETION: Export the function and data for testing

Add module.exports to export both getUserById and users so they can be used in integration tests.

Node.js

const users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' },
  { id: 3, name: 'Charlie' }
];

const testUserId = 2;

function getUserById(id) {
  return users.find(user => user.id === id);
}

// Export getUserById and users below
// Your code here

Need a hint?

Use module.exports = { getUserById, users }; to export both.