In the traditional product development process, a developer would design the product and features, develop the code for each feature, and then test it after it has already been written.
With Test-Driven Design, also known as Test-Driven Development or TDD, this process is essentially reversed. Test-Driven Development (TDD) saves companies time during development and money during production.
How does this work? With TDD, software developers can produce code of much higher quality than if they were to use the traditional processes. In addition, the Test-Driven Development process can produce bug-free code that is less prone to errors once the product has been launched. Read on to learn more about how this process leads to the most optimal code.
What Is Test-Driven Design (TDD)?
Test-Driven Design (TDD) is an iterative software development process that implements a short development cycle that is repeated until a satisfactory result is reached. Unlike more traditional development practices, TDD involves writing the unit test before building the code.
Each round of testing in TDD helps to smooth out the code and drive the product towards the desired end result. The process as a whole allows developers to develop software incrementally, producing simple, bug-free code and functions as intended.
Due to the nature of the test-before-code process, it may result in a more extended period of time spent in the development stage (though this is not always the case). TDD has the potential streamline the development process and can result in a product that is faster to market.
The amount of time and money saved once the product hits production makes utilizing the Test-Driven Development (TDD) process more than worth it. The end result can be a higher quality product with fewer bugs and errors, which means less time spent on customer service and fewer unfavorable reviews.
The Three Phases of the Test-Driven Development (TDD) Process
You will often see Test-Driven Design (TDD) described as red, green, and refactor. These terms refer to the phases of the TDD process. Remember that the Test-Development Design process is quite different from the standard development practices. The process is a bit backward in that the test is developed before the code.
The phases of the Test-Driven Development (TDD) process are:
1.The red phase. The first step in the TDD process sets a baseline for developers. Unit tests are created without any previously written code. These tests are designed with an expectation of failure; with no code, it would be virtually impossible for the tests to produce the desired result. Developers will often create these tests based on their assumptions or expectations of how a specific feature will behave. The test results can either confirm or deny those expectations and will fuel the next steps.
2. The green phase. Once the test has failed, the developer can then move on to the next step in the process: writing the code for this feature. At this stage, developers will produce the minimum amount of code necessary to pass when the test is re-executed.
3. The refactor phase. At this stage, the code has been written and the test has been passed. Now it’s time to update the code. In this phase, the developers will refactor the code, optimizing it and ensuring that it is up to an acceptable standard. Since only the bare minimum code was created for the previous step, developers will need to make adjustments now that they know the code behaves as intended.
Developers will need to repeat this three-step process for each feature until the product is completed.
Benefits of Implementing Test-Driven Development (TDD)
There are many benefits to Test-Driven Development (TDD) implementation during early design stages. This software development process benefits not only the developers on the project but the company, and the customers, and the product itself.
Test-Driven Development (TDD) can:
1.Increase the productivity of the developer team. With the test, code, refactor process outlined by TDD, developers can easily tackle each step of the project and provide results (thus making for a more productive dev team).
2. Produce better program design. By designing the tests first, there is a better understanding of the overall design and features of the project. In fact, TDD can help develop a more cohesive and clear design plan.
3. Produce higher quality code. With tests run each step of the way, bugs and errors are caught early and often. This leavesa cleaner design and higher code quality.
4. Provide fast feedback. The test-then-code process provides immediate feedback to the developer team. Developers will immediately know when something is broken with this process. They will be able to quickly identify where the problem is occurring, making for an even simpler fix.
5. Reduce the time required for project development. Thanks to the fast feedback provided by Test-Driven Design (TDD), developers are able to quickly identify errors and fix the code. Dedicating less time to debugging and reworking code keeps the project moving quickly and efficiently.
6. Reduce the time spent debugging. With Test-Driven Development (TDD), errors and bugs are caught immediately and fixed quickly. This means less time in the debugger than projects that follow more traditional software development processes.
7. Reduce time spent reworking code. Not only is the dev team able to identify errors and fix problems quickly, but the TDD process will also alert developers if their refactoring broke code that was working previously. It can mean less time reworking code later.
8. Make teamwork easier. Collaboration is easier with TDD, since the method will quickly let developers know if refactoring has created unforeseen errors. Dev team members will be able to edit the code of others and immediately know if other adjustments need to be made.
9. Make it easier to add features or update later. The unit tests created with TDD provide a safety net of sorts when the code needs to be updated, or if a new feature is added to the existing product.
10. Simplify the code. Since the developer team writes the code in response to the test results, the code is often simpler. Simplified code can make it easier to find errors, make changes, and increase the quality of the complete product.
11.Reduce the number of bugs and improve product quality. When developers write code specifically to pass the unit tests for the feature, it makes for better quality code overall. Fewer bugs mean better code and a better overall product.
Save money. If the product is hitting the market with bugs, the cost to the company can be incredibly high. Remember, it costs more than labour to fix the bugs. Errors lead to high customer service costs. Bad reviews can lead to a significant loss of revenue and a hit to the company’s reputation. Releasing a product that is not error-free can result in long-term damage that is difficult to come back from. Finding and fixing bugs during development is much more cost-effective than dealing with them during production.
Pitfalls of Test-Driven Development (TDD)
No process, no matter how beneficial, is without pitfalls. Test-Driven Development (TDD) is no different. While there are many benefits to this software development process, there are, of course, some cons that need to be considered.
There is no such thing as partial adoption. For Test-Driven Design (TDD) to work, the entire development team needs to be on board. If only a few developers utilize this process, it will never work. This must be something the dev team agrees on and implements together. Utilizing effective software that helps teams work together like SystemLink™ Software Workflows can be the difference between complete and incomplete implementation.
It can be a challenge to learn. Most developers are very set in their ways. While this process may sound simple on paper, the implementation can be very complicated initially. TDD takes time to learn and requires a lot of discipline and dedication.
It can initially slow development. The process of writing the tests can take time. In this sense, TDD can slow down the development process in the beginning. However, TDD will actually speed the process up overall once implemented. Only those early stages can seem like they are dragging everything out.
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