How Test Driven Development (TDD) Helps You Cut Development Costs

  • 7 min
  • Jan 16, 2017
Maryna Z.

Maryna Z.


Dmitriy G.

Dmitriy G.

Head of BA Office



Test driven development (TDD) is one of the best ways to ensure software quality.

By following a TDD methodology, developers create maintainable code and reduce bugs.

But it’s not only programmers who reap the benefits of test driven development; entrepreneurs and product owners stand to benefit as well. In this article we’ll talk about how you can use a TDD approach to reduce time and save money on your software project.

What is test driven development?

In a nutshell, TDD is realized through short development cycles that follow the rule “first write unit tests, then write the code, then refactor, then repeat.” Unit tests are automated tests that check whether functions work as expected. Your very first unit test should fail, since it’s written before you even have any codebase. This measure prevents developers from writing unnecessary code that doesn’t comply with the given test. After the code is written, it must pass the unit test. But even if it passes the test, code often requires polishing ‒ refactoring is the more technical term ‒ to get it to a point where it’s truly elegant. TDD fits perfectly into commonly accepted, iterative Agile methodologies of project management.

Despite TDD’s  large community of advocates, however, some developers are sceptical about this approach. Some developers claim, for instance, that test driven development consumes too much time and effort on the writing of tests in place of doing actual work. There’s some truth in this, of course. TDD takes time at the initial stage of development. But over time, TDD effectively lowers the resource requirements of your development team. Here are a few reasons why TDD is a must for your next software project.

What are the benefits of test driven development for my software project?

TDD Helps You Avoid Scope Creep

The nightmare of any project manager is scope creep – any unexpected growth in the scope of work which leads to delays in project delivery. Scope creep can happen for various reasons: poorly defined tasks, misinterpretation of project requirements, lack of documentation, etc. There are many methods aimed at mitigating scope creep, and TDD is one of them.

As we just mentioned, one common reason why scope creep occurs is lack of documentation with clearly defined requirements. This problem can be mitigated through test driven development. In a TDD environment, developers write unit tests to test particular segments ‒ units ‒ of code. Unit tests serve as specifications that describe the precise features that should be implemented. Therefore, well-specified tests prevent developers from writing superfluous code. TDD helps developers focus on what’s necessary and prevents gold plating ‒ adding unnecessary or unwanted features that weren’t specified in the project requirements.

TDD Helps You Achieve a Maintainable Codebase

Part of the TDD methodology is refactoring,  or restructuring working code to improve its readability and optimize its implementation. Refactoring contributes to a well-designed system architecture ‒ in some cases with very well-written code, even non-programmers can read it and get an idea of what’s happening.

Moreover, TDD promotes good coding principles including DRY, KISS, YAGNI and SOLID.

  • The DRY (Don’t Repeat Yourself) principle tells developers to avoid repeating the same code in different parts of the same system, which is why it’s also sometimes called the DIE principle (Duplication Is Evil). DRY recommends that developers use classes and functions to encapsulate system functionality and maintain a consistent codebase.
  • The KISS (Keep it Simple, Stupid!) principle advises developers not to reinvent the wheel, but to build simple and clear architectures. The essence of KISS is to avoid over-engineered solutions.
  • The YAGNI (You Ain’t Gonna Need It) principle fights gold plating. Gold plating might seem harmless, especially if a developer is eager to enhance existing functionality to delight a customer. However, it results in extra development time which might cause a project delay or a disgruntled customer. YAGNI makes it clear: a developer should implement only assigned tasks and avoid adding excessive functionality.
  • SOLID consists of five principles in one: single responsibility, open-closed, Liskov substitution, interface segregation, and dependency inversion. To be brief, SOLID states that following these principles makes applications easier to maintain and test.

You might read this and wonder: “Developers care about well-written, clean code, but what do I get out of it?” As a matter of fact, elegant code that is easy to modify, extend, test, and maintain has a direct bearing on a project’s success. The tidier your code, the less effort your team must put into adding new features or modifying the existing codebase.

TDD Helps You Prevent Bugs

TDD is a unique approach that ‒ when followed strictly ‒ ensures 100% test coverage. Sounds impressive? Since the primary focus of TDD is on running tests, you can be sure that your application will work as expected and require few fixes. It’s important to point out that in a TDD environment, developers focus on running tests to prevent bugs rather than to remove them after the code is written. With TDD, developers create entire test suites ‒ collections of tests ‒ which benefit projects in a number of ways.

First, test suites ensure comprehensive test coverage of the codebase, so bugs are less likely to pop up unnoticed. Second, test suites allow developers to work out potential issues before the application is ready to go into production. Finally, because test suites are constantly maintained, they guarantee software quality. Test suites must be constantly updated because new features or modifications to existing functionality mean that previously written tests will fail. Therefore, developers must continuously update test suites to ensure quality throughout the development process.

TDD Helps You Cut Development Costs

While TDD takes a lot of time and effort from developers in the very beginning, over time this process results in continuous maintenance. Thanks to 100% test coverage, you shouldn’t be afraid that your codebase will break when adding new functionality or changing existing features. Fewer issues equals fewer developer hours, which directly impact project costs.

Moreover, developers themselves say that test driven development is a more conscientious approach to building software than the conventional method of coding first and looking for bugs later. Developers admit that previously they used to write lines of code, realize that their solutions were irrelevant, and then start coding again from scratch. Unlike outdated coding practices, TDD allows developers go back to the drawing board and concentrate on designing a lightweight, flexible architecture upfront.

If we don’t practice test driven development, we still have to check our codebase, which we’ll end up doing by hand. This takes plenty of time. With TDD, developers write automated tests and run them after each new update or change to the code without having to do additional work. Besides, since manual testing is done by humans, it doesn’t guarantee full test coverage. TDD does.

TDD allows developers to focus on creating quality solutions instead of tinkering with code. Well-built architecture and comprehensive test coverage positively influence the overall project timeline, which translates into lower costs.

In spite of the controversy among developers about the advantages of test driven development, we take the side of the TDD disciples. Our team of developers believes that TDD is the promising future of software development. Here at RubyGarage, we design consistent software architectures and ensure top quality software. TDD helps us accomplish this. However, we also try to walk in our clients’ shoes – and when we do that we realize that TDD is great for business as well. Time is one of the entrepreneur’s most valuable assets, and TDD makes sure that it’s used efficiently. We would love to hear your ideas about TDD and ‒ if necessary ‒ provide you with a few additional reasons why you should hire a team who loves TDD as much as we do!




Maryna Z.

Maryna Z.


Dmitriy G.

Dmitriy G.

Head of BA Office

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