How to Ensure Testability of your Codebase

Do you want your software to be stable? You can achieve it by making your code more testable. This helps with catching bugs and errors early on, improving the development process in general, and building robust and reliable systems. Let’s get acquainted together with the meaning of testability, best practices for testable code, common challenges developers face, and the process of test automation implementing in your codebase!

1. What is testability?

Testability refers to the ease with which a piece of software can be tested and validated. A testable codebase is one that is structured and designed in such a way that it can be tested with minimal effort and minimal dependencies.

Some characteristics of testable codebase:

1. Modularity: codebase is segmented and decoupled, with understandable separation of concerns.?
2. Isolation: performance of individual functions is not dependent on each other.
3. Maintainability and readability: code is simple to understand, maintain, and update.
4. Flexibility: you can adapt your code to various scenarios and environments.?
5. Reusability: you can put code in other parts of the codebase without modification.

2. Why must you make your code testable?

Why should anyone make their code testable? This is not done to make the tester’s life uncomplicated. First, it is beneficial to the developers and a product owner. The main advantages of code testability:

1. Early bug detection: testability allows test automation implementation. You can add it at any stage of development. This saves time and effort in the long run as bugs are detected early on, but not in the production stage.
2. Improved development process: developers can change the code without breaking existing functionality. This allows for more efficient development and a faster time to market.
3. Better code quality: modularity improves code readability, making it maintainable, and less error-prone. The result is a higher-quality, reliable codebase.
4. Simple scalability: new features can be added without affecting existing functionality.?
5. Improved collaboration: developers can work together more efficiently as they can rely on automated tests to ensure that their changes don't break existing functionality. This allows for faster and more efficient development in a team setting.

3.?How do we make our code more testable?

How to make your code testable? There are many practices, and different companies develop their own as well. We will share those that are the most successful from our point of view.

1. SOLID design.?

S - Single responsibility. If the function only has a single purpose, then it won't require multiple modifications.

O - Open-closed. The code is designed to be expandable without changes to the existing codebase; you can incorporate new features but not make alterations to existing ones.?

L - Liskov substitution. A subclass should be able to substitute its parent class without compromising the correctness of the program output.

I - Interface segregation. The code follows the "many-small-interfaces" principle. Any interface is specific to certain functionality,

D - Dependency inversion. High-level modules are not dependent on low-level modules. However, both should depend on abstractions.

2. Dependency injection.?

The use of this technique gives you the ability to incorporate outside elements (such as databases, APIs, or other services) into your program instead of hard-coding them. This increases testability, as you can switch out the dependencies for simulated equivalents (such as mocks or stubs).

There are multiple ways to implement dependency injection, like constructor injection, property injection, and method injection. The key objective of these approaches is to clarify the required dependencies and keep them distinct from the code that utilizes them. By detaching the sections of code, we can make the whole thing more organized and easier to evaluate. This simplifies the testing process.

3. Tightly-coupled dependencies avoidance.

Tightly-coupled dependencies refer to the close level of interconnectedness and interdependence between multiple codebase parts. This complicates testing of individual code parts in isolation. Altering one area of the codebase can have an impact on other areas. Furthermore, this can make it tricky to comprehend the code and its intended purpose, resulting in potential glitches and mistakes.

Example: a class has a hard-coded dependency on a specific service or library. If the service or library is changed, it could cause the class to stop working. This makes it complicated to test the class in isolation, as the service or library has to be tested together with the class.

To enhance testability, reduce tight coupling and increase loose coupling.

4. Legacy code refactoring.

Refactoring legacy code involves restructuring the existing codebase without altering its external functioning.

Some techniques for legacy code refactoring are:

• Breaking up large classes or methods into smaller, more specific pieces.
• Defining interfaces for classes, which can assist in making the code more organized and loosely coupled.
• Using dependency injection.
• Removing duplicate code.
• Renaming variables, classes and methods.

Conclusion

Ensuring testability of your codebase is crucial for maintaining the integrity and stability of your software. By following best practices, such as SOLID design, dependency injection, and writing small, focused functions, you can make your code more testable. Automated testing is also an essential part of ensuring testability and catching. If you want to set up your QA processes from scratch and to learn how to make your code testable, contact Cherish DEV !