The Basics of Software Testing

Today, we'll explore one of the most annoying things for a Software Engineer. It's Software Testing!
No, I'll not make it complex. My goal is to simplify software testing.

Software testing means checking the software we have developed. It helps us catch mistakes before the users face those mistakes. Testing makes software more stable and safer to use.

Think about a food delivery app. If a food delivery app crashes when you place an order, or a banking app sends money to the wrong account, people will lose trust in it. Testing helps prevent those problems in the production environment

But Why Should I Do This Annoying Testing

Nobody writes perfect code the first time. You don't even know how many bugs you've developed. Testing finds bugs and errors early, before they turn into a bigger issue. It also saves time and effort later.

1. Unit Testing

Unit testing is the process of testing small parts of your code. Suppose you have a single function, method, or class. In unit testing, you will test those functions, classes are properly working or not

For example, you have developed an e-commerce app. Now, you might test a function called calculateDiscount(price, percent). If the price is 100 and the discount is 10%, the result should be 90.

If that test passes, your calculation works fine. Unit tests are quick to run and help catch bugs early before they spread.

Common tools we use in unit testing are JUnit (Java), Testify (Go), PyTest (Python), Jest (JavaScript)

2. Integration Testing

Integration testing is the tests that checks how different parts of your app work when they are connected. Even if each part works fine by itself, they can fail when connected. Don't get confused. It's very simple.

If we take an example of a food delivery app. In a food delivery app, the order system talks to the payment system. Integration testing makes sure that when a user orders food, payment is processed and a confirmation is sent. So, our integration test checks that the order system and payment system work together.

This kind of test finds problems with data exchange between parts of your app or the database connections.

Common tools:
JUnit (Java), Go’s httptest package, Postman, Spring Boot Test

3. End-to-End (E2E) Testing

In End-to-End testing, we mimic the behavior of the software. In E2E, the tests are written like a user were using the software.

Again, we'll see the example of an e-commerce. What type of feature do you expect to see in an e-commerce app? You’ll test signing in, adding an item to the cart, paying, and receiving confirmation. If all steps work perfectly, then the E2E test is passed.

E2E testing makes sure the full system is perfect.

Common tools:
Cypress, Selenium, Playwright, Puppeteer

Difference Between Unit, Integration, and End-to-End Testing

Type	What It Tests	Example	Scope
Unit Test	One small part of code	Checking if calculateDiscount() returns the right value	Small
Integration Test	How parts work together	Order system and payment system working together	Medium
End-to-End Test	The full user flow	From login to checkout in an e-commerce app	Large

You can think of it like building a car:

• Unit testing checks if each part (like the engine or brakes) works properly on its own.
• Integration testing checks if the engine connects correctly with the transmission.
• End-to-end testing takes the car for a drive to see if everything works together smoothly.

Other Useful Types of Testing

• Performance Testing: Checks how fast your app runs under load. For example, how your website performs when 10,000 users visit at once.
• Security Testing: Looks for vulnerabilities that attackers might exploit. For example, checking if users can access data they shouldn’t.
• Usability Testing: Ensures your app is easy to use. Real users try it and share feedback.
• Regression Testing: Makes sure new changes don’t break existing features.
• Smoke Testing: A quick check to see if basic features work after deployment.

Conclusion

A well-tested software is very important. If a software fails in production, it makes a negative impact on a company. So, software testing is a must.