Developed as an agile development technique in the late 1990s, test-driven development (TDD) presented itself as an ideal solution for limiting bugs, reducing bug-fixing costs, and accelerating software agile software development.
A study by Microsoft and IBM dating back to 2008 pointed out that initial development with TDD incurred 15-35% more development time than conventional techniques. However, the study’s authors theorized that TDD pays off in the long term by reducing debugging time and encouraging incremental and iterative development.
Fast forward to today, and TDD is, well and truly, driving agile software development. This article serves as an introduction to what is TDD and how it benefits businesses in end-to-end product development.
An overview of TDD
TDD meaning Test-Driven Development. The most basic premise of TDD is to write a test case for a simple, functional component. This test is generally a failure test of the most straightforward function that requires implementation.
Subsequently, you write the most basic code to accommodate the test case scenario, i.e., pass the test. This way, the code is “refactored” to suffice the required functionality.
This means that TDD supports writing test cases first and adjusting the code accordingly. Thus, in essence, tests drive the code, not the other way around.
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The many business benefits of TDD
TDD has grown to a point where it is now a mainstream development practice. It’s only natural for businesses to convert to this practice. That said, it helps derive a plethora of business benefits.
A focus on requirements right from the start
As elucidated above, TDD is about writing tests first and everything else second. As a result, this practice helps capturing requirements right at the beginning of the project. This ensures that the code is written in a manner that:
- It does not contain any underlying assumptions about the critical functional requirements
- It entirely focuses on the outlined test case scenario
The coding phase is inevitably much more refined and business-focused with this as a baseline.
Reduced programming sophistication
When serving varying demographics, your application incorporates a certain degree of complexity. And the underlying architecture and code handle this complexity.
But with TDD, such sophistication doesn’t come in the way of the test creation process. Moreover, the extensive focus on test cases ensures that the code evolves structurally. It’s noteworthy that such orderly evolution in code would also result in a more refined and stable architecture.
Consider this; the developers need to work through a simple process whenever a new function is added:
- Write the test case scenario
- Prepare the code to pass the test case
- Refactor the existing and new code to make it more stable
Documentation for cross-functional teams
Of course, TDD accrues several benefits for both developers and enterprises. But what about documentation? During tests, developers are drawn to the test cases and code in a specific sequence. This ensures that they are focused on their task of writing the most basic code.
But at the same time, all the test cases combined provide a comprehensive description of the feature. Thus, TDD does not require any separate code documentation, at least in terms of what the technical team needs to comprehend the feature.
Naturally, the documentation must be much more consumable for a more layman audience. TDD gives a head start to such teams because of the functional simplicity involved.
Since the documentation is organized right off the bat, it’s relatively easier for anyone from the cross-functional team who’s joining in to collaborate or perhaps replace someone absent.
On that note, TDD serves to:
- Reduce the feedback time from cross-functional teams
- Expedite better design and code architecture decisions
- Increase the likelihood of delivery of better-quality products
Automation and test coverage
TDD’s principle of writing automated test scripts to help drive agile development for quality assurance is a compelling aspect of the practice. The unit tests created through TDD enable much better results for later verification.
Because each unit test leads to code creation and ultimately refactoring, TDD expedites a 100% test coverage. This effectively translates to a better bug-free code. Considering how tough it is to track down bugs and their corresponding fixes, writing such a high coverage of test cases can go a long way in helping the QA team come up with a clean slate.
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Rapid change accommodation
Agility, flexibility, scalability, and adaptability are all pretty much the foundations of agile development and the associated TDD. With TDD, developers have thorough knowledge and documentation of each of the specific functionalities that the application must offer.
This goes a long way in refactoring on-demand, i.e., if a new function is added to the application, its corresponding unit test will come into existence. Subsequently, the developer will update the code to pass the test.
As such, TDD helps accommodate any immediate changes or additions required for any of the existing functionalities.
Nothing’s more important than getting the right feedback at the right time. And to make this happen, TDD supports frequent feedback on the development and, on a holistic level, the business needs.
The whole process of writing functional test cases and the resulting refined code is a swift way of getting feedback on the most basic must-have application functionalities.
As a result, each of the hypotheses in building and refining the application is validated right away. It’s, thus, safe to assume that the application has a higher chance of eliciting positive feedback from the end-users right off the bat.
In a Nutshell - TDD Cultivates Agile Teams
As seen above, TDD centers itself around the development of automated tests. With the creation of such tests, it’s easier for developers to work through a repetitive process.
The resulting automation in this process helps a team focus on the development at hand rather than on the larger technicalities. The focus on the development is further complemented by the team’s ownership of the code and its subsequent evolution. This all helps to create a high likelihood that there’ll be no bugs or missing features.
Best of all, TDD helps teams evolve around a standard methodology rather than just being a part of the normal development process. In this case, it’s up to the developers and businesses to ensure that the functionality and the associated code evolve in an orderly fashion.