The Pros and Cons of Test-Driven Development

Posted in: Quality assurance testing, Web and software development by: Simon Hill on:

Over the last decade, Agile development methodology has grown dominant. Developers are increasingly focusing on speed-to-market and looking to boost the frequency of software releases. The trend towards continuous delivery requires greater efficiency in the process. Many developers are relying on automated unit tests, or pushing further into Test-Driven Development (TDD).

The idea behind Test-Driven Development is to write the tests before writing the code. This helps to encourage the developers to not lose focus on their goal, only building the functionality to pass the test. This approach has potential advantages and pitfalls.


Pros of Test-Driven Development

Proponents of TDD suggest that it leads to higher quality software in less time. Which is effectively saving money from a management point-of-view. If we drill down, there are various pros to TDD, such as:

  • It can lead to simple, elegant, modular code.
  • It can help developers find defects and bugs earlier than they otherwise would. It’s a common belief that a bug is cheaper to fix the earlier you find it.
  • The tests can serve as a kind of live documentation and make the code much easier to understand.
  • It’s easier to maintain and refactor code, your own and other programmer’s code.
  • It can speed up development in the long-term.
  • It can encourage developers to think from an end user point-of-view.

Cons of Test-Driven Development

In the absence of a lot of statistical evidence, it’s tough to say TDD definitely delivers. There’s no such thing as a one-size-fits-all solution in software development. Now, let’s take a look at some of the potential disadvantages:

  • It necessitates a lot of time and effort up front, which can make development feel slow to begin with.
  • Focusing on the simplest design now and not thinking ahead can mean major refactoring requirements.
  • It’s difficult to write good tests that cover the essentials and avoid the superfluous.
  • It takes time and effort to maintain the test suite – it must be reconfigured for maximum value.
  • If the design is changing rapidly, you’ll need to keep changing your tests. You could end up wasting a lot of time writing tests for features that are quickly dropped.

Make Sure TDD is the Right Fit

TDD can boost confidence, but it can also create a false sense of security. Pushing TDD further to cover acceptance criteria is another possibility, but, as we’ve discussed before, automated testing isn’t a substitute for real testers. You always need a mix of the two.

Ultimately, you really need to take the time to ensure that test-driven development is the right approach for your project. If you decide that it is, then ensure that everyone is on board with it. With legacy systems and older apps that lack a unit-testing framework, it’s not always going to be an easy fit. However, if you’re starting a new project and the design is nailed down, it could be your fastest and cheapest route to a quality product.


Simon Hill

Simon is an experienced freelance technology journalist covering mobile technology, software, and videogames for a wide variety of clients in print and online. He regularly contributes to Digital Trends, Tech Radar, and Android Authority, and he ghostwrites for CEOs in the technology space. After completing a Masters in Scottish History at Edinburgh University, he began his career as a games tester, progressing to lead tester, game designer, and finally producer, before leaving the industry to write full time. He is passionate about the potential for good software and hardware to improve our lives, and strongly believes that thorough testing is a vital prerequisite for greatness.