Greetings. So we are back with test cases and someone recently told me food > drinks, and why I am telling you this? Because test cases > functions, let's all hail to test case supremacy.

Enough of my nonsensical talk, let's dive straight into this!

JavaScript Testing with Jest

Now, don't get started on I didn't mentioned anything about jest or even javaScript before. That's how it goes here!

What is Jest?

Its an open-source JavaScript testing framework developed by Facebook. It has become a popular choice for testing JavaScript applications, offering a simple and powerful way to ensure the reliability and correctness of your code.

Few Key Features of jest:

Zero Configuration
Fast and Parallelised
Snapshot Testing
Mocking
Built-in Expectations
Support for Asynchronous Testing

Not, going deeper on these features in this blog, might cover them some other time.

Installing Jest

Getting Jest up and running is a breeze. If you haven't installed it yet, run the following command in your project directory:

npm install --save-dev jest

Writing Your First Test

Let's create a simple function and test it. In a file named math.js, write a function:

// math.js
function add(a, b) {
  return a + b;
}

module.exports = add;

Now, let's write a Jest test for this function. Create a file named math.test.js:

// math.test.js
const add = require('./math');

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

Running Jest

Run your tests with:

npx jest

Jest will execute your test, and you should see a delightful green check mark indicating success.

What's Next?

Test Cases for Dessert!

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Test Cases for Main Course!