Testing helps us identify potential errors and ensures the system's stability at all stages of development. An application can only be deemed fully ready for use after tests have been written.

What is Backend Application Testing?

This is a part of development that many backend developers dislike, as it requires writing tests for almost all created code. This means checking every step of a specific method's operation to ensure its accuracy.

Example from Real Life When Tests are Beneficial

Let's consider an online store. When updating the code for the shopping cart, a developer might accidentally affect the discount calculation logic. Without tests, this error might only surface in production when customers notice incorrect pricing.

However, if tests for price and discount calculations are written, the error will be caught during the development phase, preventing issues in production and customer dissatisfaction.

What Happens if Tests aren't Written?

In 2012, Knight Capital suffered catastrophic consequences when a new application was deployed without proper testing.

Specializing in high-frequency trading, the company released software that contained bugs, leading to incorrect trades and losses of $440 million in just 45 minutes. This incident forced Knight Capital to seek emergency funding and ultimately resulted in its acquisition by another firm.

This case highlights how the lack of testing can lead to application failures and significant financial losses. Proper testing could have caught the errors during the development phase, potentially preventing the disaster.

Summary

Testing backend applications is a critical part of the development process that helps avoid errors and maintain high code quality. Unit tests check individual parts of the system, while integration tests verify how they interact. Both types are essential for building a reliable and stable product.