Forem: Ndoma Precious

9 Best AI Job Application Tools in 2025

Ndoma Precious — Thu, 24 Jul 2025 09:22:11 +0000

Let’s be real for a second: looking for a job is soul-crushing.

You pour hours into polishing your resume until your eyes glaze over. You write cover letters so personalized they feel like love letters to a corporation. You fill out the same information on a hundred different forms. And for what? To be ghosted. The silence is deafening, and most of the time, you’re just shouting into the void.

I was stuck in that cycle for months. Then I found something that felt like cheating: AI tools that don’t just help you apply, they do it for you. I'm not talking about asking a chatbot to rephrase a bullet point. I’m talking about software that finds jobs, tailors your resume for each one, and applies on your behalf while you’re making coffee or, you know, sleeping.

Suddenly, the numbers started to shift. I wasn’t just getting more replies; I was getting more interviews. And it’s not just me. People using these tools are seeing way more callbacks because they can play the numbers game without sacrificing quality.

If you’re still dragging and dropping your resume into one application at a time, you’re fighting a battle you can’t win. The smartest people on the job hunt in 2025 have handed the grunt work over to AI so they can focus on what a robot can’t do: acing the interview and making real connections.

This is my breakdown of the best tools out there that will completely overhaul your job search.

The Game is Rigged. Here’s How to Fight Back.

The job market is a beast. Companies post a job and get swamped with hundreds of applicants. To cope, they use Applicant Tracking Systems (ATS)—robots that scan your resume and toss it in the virtual trash before a human ever lays eyes on it. It’s not personal; it’s just code.

You have two options: keep playing their game and hope for the best, or get your own robots to fight on your side.

This is where AI application tools come in. They fix the three biggest headaches of the job hunt:

You can go for both quality AND quantity. The old way forced a choice: send out a generic resume to 50 places or spend a whole day perfecting three applications. AI kills that dilemma. It customizes everything for every single job, in seconds.
Your application actually lands on someone’s desk. More than 90% of big companies rely on ATS. These systems are picky, rejecting resumes for silly things like the wrong file format or missing keywords. AI tools are built specifically to get past these digital gatekeepers.
You get your time back. Seriously, a single manual application can take an hour or more. An AI tool can fire off dozens in that same amount of time, freeing you up to do literally anything else.

Look, your competition is already doing this. If you’re not, you’re starting every race a lap behind.

How to Use These Tools Without Sounding Like a Bot

Most people get this wrong. They dump a few bullet points from their old resume into the AI and expect a miracle. That’s not how this works. The AI is only as smart as the information you give it.

To get results that actually sound like you, you need to feed the machine properly. Here's what I learned the hard way:

Give it the whole job description, not just the link. Copy and paste everything: the weird corporate jargon, the list of "nice-to-haves," the company's "about us" spiel. Context is everything.
Brag about yourself with numbers. Don't say you were "responsible for sales." Say you "grew the Midwest sales territory by 40% in six months." Give it concrete achievements it can use.
Dump your entire skill set in there. Every piece of software you’ve ever touched, every language you speak, every certification you’ve earned. The AI will cherry-pick the right ones for each job.
Tell it what you actually want. Be specific about your salary goals, the kind of company culture you thrive in, and what you want to do next. This stops it from applying to jobs you’d hate.
Add some industry flavor. What are the buzzwords? What are the big challenges in your field right now? Sprinkling this in makes you sound like an insider, not a random applicant.

The trick is to build a detailed "master profile" with all this info. Spend an hour on it once, and you’ll save a hundred hours down the road.

The 10 Best AI Job Application Tools for 2025

1. FastApply - The One I Wish I'd Found Sooner

Honestly, FastApply feels like the tool someone built after getting completely fed up with the job hunting process. It doesn't just help you write—it takes over the entire application process for you. It felt like I’d hired a personal assistant whose only job was to get me interviews.

What makes it the clear winner for me:

It applies everywhere, nonstop. It connects to LinkedIn, Indeed, and other major boards and just goes to work, submitting over 150 targeted applications a day based on the criteria you set. There are no weird daily caps.
It creates genuinely unique resumes. This is the key. It doesn't just slot keywords into a template. It rewrites your resume from the ground up for every single job, so each one looks like you spent hours on it.
The cover letters don't suck. The AI actually reads the job description and the company’s website to write a cover letter that speaks to what they’re looking for.
You can see everything in one place. No more messy spreadsheets. A single dashboard shows you every job it applied to, who’s responded, and where your interviews are.
It's smart. The AI learns from your preferences and gets better over time, so you're not wasting applications on jobs that aren't a good fit.

They're also adding Glassdoor and ZipRecruiter automation soon, plus a feature to cold-email companies directly. The setup is dead simple: you log in, fill out your profile with all that good info we talked about, set your filters, and let it run. That’s it.

2. ResumeGenius AI - For Getting Past the Corporate Robots

If you're aiming for a Fortune 500 company, your biggest enemy is the ATS. ResumeGenius AI is a specialist tool laser-focused on winning that one fight. It dissects job descriptions and tells you exactly what keywords and phrases you need to add to your resume. It also handles all the formatting to make sure the scanning software can read it perfectly. This is your tool if you're tired of getting filtered out by a machine.

3. CoverLetterBot - For People Who Hate Writing Cover Letters

This one is clever. Instead of making you fill out a form, CoverLetterBot chats with you to create a cover letter. It asks smart questions about the role and your experience, and its conversational style helps it capture your voice. The letters come out sounding surprisingly natural and tailored to the company's vibe. It’s perfect if you find yourself staring at a blank page.

4. Sonara - The Market Blitz

Sonar is built for one thing: speed and saturation. If your strategy is to blanket the market and see what bites, this is your tool. It's designed for high-volume applications and is particularly good at sniffing out postings on smaller, niche job boards that other platforms might miss. The customization is lighter than the premium tools, but for pure, unadulterated exposure, it’s hard to beat.

5. JobHunter AI - The Strategist

This tool is for more than just applying; it’s for career planning. JobHunter AI analyzes your background and goals against current market trends to help you figure out which jobs you should be targeting for long-term growth. Then, it automates the application process for those strategic roles. It's a great fit for mid-career folks who are thinking about their next five years, not just their next job.

6. QuickApply Suite - Simple and Solid

No frills, no fuss. QuickApply Suite does the basics and does them well. It handles resume tweaking and submitting applications on the big job boards. The interface is clean and simple. If you want automation without a steep learning curve or a million features you won't use, this is a reliable choice.

7. [SmartResume Builder](https://www.smartresume.com/ - For When Looks Matter

If you’re in a creative field like design or marketing, a boring black-and-white resume won't cut it. SmartResume Builder uses AI to generate the content but puts a heavy emphasis on professional, visually striking templates. It creates resumes that look good to a human while still being readable by the ATS robots.

8. JobBot Express - The Budget-Friendly Option

Want to see what this is all about without a big financial commitment? JobBot Express offers the core features—AI-driven resume tailoring and automated applications—at a lower price. It's not as powerful as the premium options, but it's a great starting point for students, recent grads, or anyone watching their wallet.

9. Pathfinder AI - The Career Navigator

This tool starts a step before everyone else. Pathfinder AI is for when you're not just looking for a job, but trying to figure out what's next. It analyzes your skills and experience to suggest new career paths you might not have considered and identifies any skill gaps. Once you have a direction, then it starts automating applications for roles that fit the new plan. It’s part career coach, part application machine.

So, What Now?

Trying to find a job in 2025 without using AI is like trying to build a house with a hand saw. You can do it, but you're making it way, way harder on yourself.

The question isn't if you should use these tools, but which one fits you.

For my money, FastApply is the most complete solution because it solves the main problem: getting enough high-quality, personalized applications out the door to actually make a difference. The other tools are great for specific needs, but FastApply is the one that covers all the bases for most people.

You can set it up in about 15 minutes. Within a day, you’ll see applications going out. Most people start getting interview requests within the first week.

The job market is a tough place, but for the first time, we have tools that can level the playing field. Your competition is already on board. It’s time you were, too.

Testing Asynchronous Code in Node.js

Ndoma Precious — Sat, 18 May 2024 00:00:20 +0000

Testing asynchronous code is crucial in Node.js applications since they rely heavily on non-blocking operations. Let's explore how to test callbacks, promises, async/await, handle timeouts, race conditions, and event-driven code using Jest.

In this tutorial, We'll cover:

Testing callbacks, promises, and async/await
Handling timeouts and race conditions
Testing event-driven code

We'll use Jest as our testing framework throughout.

Setting Up the Project

First, we'll set up our Node.js project and install Jest. Create a new directory for the project and initialize it:

mkdir async-testing
cd async-testing
npm init -y

Install Jest as a development dependency:

npm install --save-dev jest

Update the package.json to add a test script:

"scripts": {
  "test": "jest"
}

Testing Callbacks

Creating the Callback Function

Let's start by creating a simple function that uses a callback. This function will simulate fetching data asynchronously. Create a new file named async.js:

// async.js
function fetchData(callback) {
  setTimeout(() => {
    callback('peanut butter');
  }, 1000);
}

module.exports = fetchData;

This fetchData function waits for 1 second before calling the provided callback with the string "peanut butter".

Writing Tests for Callbacks

Create a new file named async.test.js:

// async.test.js
const fetchData = require('./async');

test('the data is peanut butter', (done) => {
  function callback(data) {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  }

  fetchData(callback);
});

In this test, we use Jest’s done callback to handle the asynchronous test. The done callback signals to Jest that the test is complete, allowing us to verify that fetchData calls the provided callback with the expected value.

Testing Promises

Creating the Promise Function

Next, we'll convert our fetchData function to use promises. Update async.js to include the promise-based function:

// async.js
function fetchData(callback) {
  setTimeout(() => {
    callback('peanut butter');
  }, 1000);
}

function fetchDataPromise() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve('peanut butter');
    }, 1000);
  });
}

module.exports = { fetchData, fetchDataPromise };

The fetchDataPromise function returns a promise that resolves to "peanut butter" after 1 second.

Writing Tests for Promises

Update async.test.js to include tests for the promise-based function:

// async.test.js
const { fetchData, fetchDataPromise } = require('./async');

test('the data is peanut butter', (done) => {
  function callback(data) {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  }

  fetchData(callback);
});

test('the data is peanut butter (promise)', () => {
  return fetchDataPromise().then(data => {
    expect(data).toBe('peanut butter');
  });
});

Here, we return the promise from our test. Jest waits for the promise to resolve before it considers the test complete.

Using async/await

Update async.test.js to include a test using async/await:

// async.test.js
const { fetchData, fetchDataPromise } = require('./async');

test('the data is peanut butter', (done) => {
  function callback(data) {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  }

  fetchData(callback);
});

test('the data is peanut butter (promise)', () => {
  return fetchDataPromise().then(data => {
    expect(data).toBe('peanut butter');
  });
});

test('the data is peanut butter (async/await)', async () => {
  const data = await fetchDataPromise();
  expect(data).toBe('peanut butter');
});

With async/await, the test code becomes cleaner and easier to read. The await keyword pauses the function execution until the promise resolves.

Handling Timeouts and Race Conditions

Creating a Function with a Timeout

Let's add a timeout to our promise-based function to simulate a longer-running task.

Update async.js to include the timeout function:

// async.js
function fetchData(callback) {
  setTimeout(() => {
    callback('peanut butter');
  }, 1000);
}

function fetchDataPromise() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve('peanut butter');
    }, 1000);
  });
}

function fetchDataWithTimeout() {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve('peanut butter');
    }, 1000);

    setTimeout(() => {
      reject(new Error('timeout'));
    }, 2000);
  });
}

module.exports = { fetchData, fetchDataPromise, fetchDataWithTimeout };

The fetchDataWithTimeout function resolves after 1 second but will reject if not resolved within 2 seconds.

Writing Tests for Timeouts and Race Conditions

Update async.test.js to include tests for the timeout function:

// async.test.js
const { fetchData, fetchDataPromise, fetchDataWithTimeout } = require('./async');

test('the data is peanut butter', (done) => {
  function callback(data) {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  }

  fetchData(callback);
});

test('the data is peanut butter (promise)', () => {
  return fetchDataPromise().then(data => {
    expect(data).toBe('peanut butter');
  });
});

test('the data is peanut butter (async/await)', async () => {
  const data = await fetchDataPromise();
  expect(data).toBe('peanut butter');
});

test('the data is peanut butter (timeout)', async () => {
  await expect(fetchDataWithTimeout()).resolves.toBe('peanut butter');
});

test('throws an error if it times out', async () => {
  jest.useFakeTimers();

  const promise = fetchDataWithTimeout();

  jest.advanceTimersByTime(2000);

  await expect(promise).rejects.toThrow('timeout');
  jest.useRealTimers();
});

In the timeout test, we use Jest's timer mocks to simulate the passage of time.

Testing Event-Driven Code

Creating the Event-Driven Function

Let's create a function that uses Node.js's EventEmitter. Update async.js to include the event-driven function:

// async.js
const EventEmitter = require('events');

class MyEmitter extends EventEmitter {}

const myEmitter = new MyEmitter();

function emitEvent() {
  setTimeout(() => {
    myEmitter.emit('event', 'peanut butter');
  }, 1000);
}

module.exports = { myEmitter, emitEvent, fetchData, fetchDataPromise, fetchDataWithTimeout };

Here, we have an EventEmitter that emits an event after 1 second.

Writing Tests for Event-Driven Code

Update async.test.js to include tests for the event-driven function:

// async.test.js
const { myEmitter, emitEvent, fetchData, fetchDataPromise, fetchDataWithTimeout } = require('./async');

test('the data is peanut butter', (done) => {
  function callback(data) {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  }

  fetchData(callback);
});

test('the data is peanut butter (promise)', () => {
  return fetchDataPromise().then(data => {
    expect(data).toBe('peanut butter');
  });
});

test('the data is peanut butter (async/await)', async () => {
  const data = await fetchDataPromise();
  expect(data).toBe('peanut butter');
});

test('the data is peanut butter (timeout)', async () => {
  await expect(fetchDataWithTimeout()).resolves.toBe('peanut butter');
});

test('throws an error if it times out', async () => {
  jest.useFakeTimers();

  const promise = fetchDataWithTimeout();

  jest.advanceTimersByTime(2000);

  await expect(promise).rejects.toThrow('timeout');
  jest.useRealTimers();
});

test('event emits with peanut butter', (done) => {
  myEmitter.once('event', (data) => {
    try {
      expect(data).toBe('peanut butter');
      done();
    } catch (error) {
      done(error);
    }
  });

  emitEvent();
});

In this test, we listen for the event using once, ensuring the callback is called only once. When the event is emitted, we check that the data matches the expected value.

Conclusion

Testing asynchronous code in Node.js is crucial for ensuring your applications work correctly. In this guide, we covered how to test callbacks, promises, async/await, handle timeouts, race conditions, and event-driven code. By following these examples and writing comprehensive tests, you can make your Node.js applications more robust and reliable. Happy testing!

End-to-End Testing with Node.js

Ndoma Precious — Fri, 17 May 2024 23:25:53 +0000

End-to-End (E2E) testing is like walking through your application as a user would. It helps you ensure that everything works together as expected. In this tutorial, we'll set up E2E testing for a Node.js application using Jest and Puppeteer. Let’s get started!

Creating a New Node.js Project

First, we'll create a new directory for our project and initialize a new Node.js project.

Open your terminal and run the following commands:

mkdir e2e-testing
cd e2e-testing
npm init -y

This will create a new directory named e2e-testing and initialize a Node.js project inside it.

Installing Express

Next, we'll install Express, a popular Node.js framework for building web applications.

npm install express

Creating a Simple Express Server

Now, let's create a simple Express server. Create a file named app.js and add the following code:

const express = require('express');
const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.send('Hello, world!');
});

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`);
});

This code sets up a basic server that responds with "Hello, world!" when you visit the root URL.

Running Your Server

Run your server by executing the following command in your terminal:

node app.js

You should see a message saying Example app listening at http://localhost:3000. Open your browser and navigate to http://localhost:3000 to see the message.

Installing Jest and Puppeteer

We need Jest for our testing framework and Puppeteer to control a headless browser for our E2E tests.

npm install --save-dev jest puppeteer

Configuring Jest

We'll configure Jest to use Puppeteer. In your package.json file, add the following Jest configuration:

"scripts": {
  "test": "jest"
},
"jest": {
  "preset": "jest-puppeteer"
}

Installing Jest-Puppeteer Preset

We need to install the Jest-Puppeteer preset to integrate Jest with Puppeteer seamlessly.

npm install --save-dev jest-puppeteer

Creating a Jest Configuration File

Create a file named jest-puppeteer.config.js with the following content:

module.exports = {
  launch: {
    headless: true, // set to false if you want to see the browser while testing
  },
};

This configuration tells Puppeteer to run in headless mode (without a visible browser).

Creating a Test Directory

Create a directory named tests to store our test files.

mkdir tests

Creating a Test File

Inside the tests directory, create a file named app.test.js and add the following code:

const puppeteer = require('puppeteer');

describe('App', () => {
  let browser;
  let page;

  beforeAll(async () => {
    browser = await puppeteer.launch();
    page = await browser.newPage();
  });

  afterAll(async () => {
    await browser.close();
  });

  test('should display "Hello, world!" on the home page', async () => {
    await page.goto('http://localhost:3000');
    await page.waitForSelector('body');
    const text = await page.$eval('body', (e) => e.textContent);
    expect(text).toContain('Hello, world!');
  });
});

Running Your Test

Run your test by executing the following command:

npm test

Jest will start Puppeteer, open a browser, navigate to http://localhost:3000, and check if the text "Hello, world!" is present on the page. If everything is set up correctly, the test should pass.

Advanced Testing

Now, let's add more functionality to our application and write tests for it.

Update Your Express Server

Modify app.js to include a simple form that greets the user:

const express = require('express');
const app = express();
const port = 3000;

app.use(express.urlencoded({ extended: true }));

app.get('/', (req, res) => {
  res.send(`
    <form action="/greet" method="post">
      <input type="text" name="name" placeholder="Enter your name" />
      <button type="submit">Submit</button>
    </form>
  `);
});

app.post('/greet', (req, res) => {
  const name = req.body.name;
  res.send(`Hello, ${name}!`);
});

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`);
});

Writing a Test for the Form

Add a new test in app.test.js:

test('should submit the form and display a greeting', async () => {
  await page.goto('http://localhost:3000');
  await page.type('input[name=name]', 'John');
  await page.click('button[type=submit]');
  await page.waitForSelector('body');
  const text = await page.$eval('body', (e) => e.textContent);
  expect(text).toBe('Hello, John!');
});

Running Your Tests Again

Run your tests by executing the command:

npm test

Puppeteer will open the form, type a name into the input field, submit the form, and check if the greeting message is displayed correctly.

Conclusion

You've successfully set up and run End-to-End tests for a Node.js application using Jest and Puppeteer! We covered:

Introduction to Testing in Node.js

Ndoma Precious — Fri, 17 May 2024 22:36:13 +0000

Testing is an inevitable part of the software development process, and it's no more a surprise when it comes to Node. js applications. Testing gives you an opportunity to make sure that your code does exactly what it is supposed to do, detects bugs and regressions early in the development process, and improves the quality and ease of your code base maintenance.

In this tutorial, we'll cover the importance of testing, different types of tests, and the concepts of Test-Driven Development (TDD) and Behavior-Driven Development (BDD).

Importance of Testing

Testing is essential for several reasons:

Catch Bugs Early: The tests will help you find the bugs and problems in your code before the production phase, thus saving you from expensive fixes and maintenance efforts in the future.
Ensure Code Quality: Well-written tests not only act as the documentation for the code but also guide you to understand the code and keep it well-maintained. The unit tests also serve as an example of good coding practices and help to avoid regressions when implementing new features or refactoring the existing code.
Improve Collaboration: Tests give the safety net for the developers working on the same codebase, and if one person introduces the change, it won't break the existing functionality.
Facilitate Refactoring: When you have a well-defined test case, you can easily refactor your code without fearing that the tests will not catch changes in behavior

Types of Tests

There are several types of tests that you might encounter in a Node.js project:

Unit Tests: Unit tests focus on testing individual functions or modules in isolation. They verify that a particular piece of code works as expected under various conditions and inputs.
Integration Tests: Integration tests verify that different modules or components of your application work together correctly. They test the interactions between different parts of the system.
End-to-End (E2E) Tests: End-to-End tests simulate real-world scenarios and test your application from the user's perspective. These tests are essential for ensuring that your application functions as expected from start to finish.

Test-Driven Development (TDD)

Test-Driven Development (TDD) is a software development technique in which you write the test cases before writing the actual code. The TDD cycle consists of the following steps:The TDD cycle consists of the following steps:

Write a failing test: Begin by creating a test for the feature that you would like to implement. First observation should show the test failure because there is no code yet.
Write the minimal code to pass the test: Write a minimal amount of code which is enough to make a test pass. At this time, you don’t worry about edge cases or optimizations.
Refactor: After the test is over, refactor the code to enhance the design, readability and performance, but make sure that all present tests still pass.
Repeat: Repeat the cycle by having a new test written for the next function.

When you are using the TDD approach, you end up with a strong and well-tested code base built from the ground.

Behavior-Driven Development (BDD)

Behavior-driven development (BDD) is a TDD extension that puts more emphasis on the behavior of your application and uses a domain-specific language (DSL). BDD tests are written using a more human-readable format, so they are less difficult to understand for both developers and non-technical stakeholders.
BDD tests are typically structured using the "Given, When, Then" syntax:BDD tests are typically structured using the "Given, When, Then" syntax:

Given: The starting position or conditions for the test scenario.
When: The stimulus is the action or the event which evokes the behavior that is being measured.
Then: The specific response or response of the behavior.

This structure makes it easy to articulate the functionality of your application and facilitates the interaction between developers, testers, and business stakeholders.

Testing in a Node.js

Let's look at some code examples to illustrate the concepts we've discussed so far. We'll be using the popular testing framework Jest for our examples.

Writing Unit Tests

Here's an example of a simple unit test for a function that calculates the sum of two numbers:

function sum(a, b) {
  return a + b;
}

module.exports = sum;
javascriptCopy code// sum.test.js
const sum = require('./sum');

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

In this example, we define a function sum that takes two numbers as arguments and returns their sum. The test file sum.test.js imports the sum function and uses Jest's test function to define a test case. The expect function is used to assert that the result of calling sum(1, 2) is equal to 3.

Writing a TDD Test

Here's an example of how you might implement the TDD cycle for a simple function that checks if a given number is even:

Write a failing test:

const isEven = require('./isEven');

test('returns true for even numbers', () => {
  expect(isEven(4)).toBe(true);
});

test('returns false for odd numbers', () => {
  expect(isEven(3)).toBe(false);
});

Write the minimal code to pass the test:

function isEven(num) {
  return true;
}

module.exports = isEven;

Now refactor the code:

function isEven(num) {
  return num % 2 === 0;
}
module.exports = isEven;

Repeat: Add more tests for edge cases or additional functionality.

Writing a BDD Test

Here is an example of how you can structure a BDD test using Jest and the Gherkin syntax:

function add(a, b) {
  return a + b;
}

function subtract(a, b) {
  return a - b;
}

module.exports = { add, subtract };

const { add, subtract } = require('./calculator');

describe('Calculator', () => {
  describe('Addition', () => {
    test('Given two positive numbers, when added, then returns the sum', () => {
      // Given
      const a = 3;
      const b = 5;

      // When
      const result = add(a, b);

      // Then
      expect(result).toBe(8);
    });

    // Add more tests for addition here
  });

  describe('Subtraction', () => {
    test('Given two positive numbers, when subtracted, then returns the difference', () => {
      // Given
      const a = 10;
      const b = 3;

      // When
      const result = subtract(a, b);

      // Then
      expect(result).toBe(7);
    });

    // Add more tests for subtraction here
  });
});

In this example, we use Jest's describe function to group related tests. The outer describe block is for the "Calculator" feature, and the inner describe blocks group tests for the "Addition" and "Subtraction" behaviors. Each test follows the "Given, When, Then" structure, making it easy to understand the context and expected behavior.

These examples should give you a basic understanding of testing in Node.js and how to get started with unit tests, TDD, and BDD. As you progress further, you can explore more advanced topics, such as integration testing, end-to-end testing, and testing asynchronous code.