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How to Implement a Test-Driven Development Strategy

By Felix Zoot Billson, Head of Marketing, Global App Testing 

Development is at the center of every successful business, whichever sector it operates in. Coding and technological advances are at the heart of this development, but how do you ensure that your coding and software solutions will perform effectively and efficiently?

Test-driven development is the key, and it has the potential to transform the worlds of coding, computing and business. It’s a fact that budgets are tight across the board, and developers often find themselves operating within tight strictures on time and money. Nevertheless, a test-driven development strategy can be one of the best investments a business will make, and we’ll show you why.

What is Test-Driven Development?

Test-Driven Development, commonly referred to as TDD, can be a powerful, transformative coding process, and yet it's easy to understand.

Put simply, it's a process that thoroughly tests and evaluates code as it's being written. This means that it performs two essential tasks: it tests code, and it validates code. Done correctly, it leads to code which is correct and reliable, so that tasks are performed effectively time after time.

At the heart of this simple concept are a number of different testing strategies. Commonly used within a TDD strategy are unit testing, user interface testing, and regression testing. This suite of tests, thoroughly carried out, creates a holistic solution that brings real benefits.

Why is Test-Driven Development Important?

We all know how important it is to invest wisely, whether in our personal lives or in a business environment. A smart investment today can allow a business to grow tomorrow, which is why a robust IT backup plan and business continuity software are so vital.

Well-executed test-driven development strategies are just as vital, as they allow you to discover potential problems or weaknesses along the way rather than waiting for the coding to be ‘finished' and put into a live situation.

This can bring significant savings for the business, as finding solutions en route is much easier than trying to patch and repair a system which has been put into development. It also ensures code that's lean, powerful, and fit for purpose, and it can help develop a system which performs much better than it otherwise would have done.

These are obvious benefits for the business who will be using the completed program, but it's beneficial to the coder too. Not only will a test-driven development strategy save them time in the long run, it also helps them gain a reputation for high quality work that can be relied upon.


Source: Pixabay

Your Four Steps to TDD Implementation

Now you know what test-driven development is, and why it's important for businesses and developers alike, it's time to look at how to implement an effective test-driven development strategy. It can be easier than you think if you follow this four step plan:

1. Write A Test

Testing is the central element of TDD solutions, and specifically unit testing. That's why it's vital that the software is testable, and that the developer can therefore create tests which test each section, or unit, of the code.

One element which distinguishes test-driven development from other testing strategy is that the test is created before the code which will allow it to pass. This means that the test will always fail in the first instance.

It's a good idea to think of TDD testing like a traffic light, with three key stages as follows:

  • Red: write a test which fails due to missing content in the code
  • Amber: write the code which fulfils the missing element, passing the test
  • Green: fine tune the amended code base in a refactoring process

It's essential that the developer can anticipate the correct function of the code even before it has been written, and create a test accordingly. A detailed and clearly set out brief will help them achieve this, as will comprehensive process documentation.

2. Start The Test

With this pre-emptive code written, it's time to run the test and see what results are obtained. The units tested in this way will vary, but they can typically be a method within the code, a class or a function that forms part of a class.

Tests are written and then executed one test at a time. In this way the developer can be sure that the test they were running has proceeded as they wanted it to, rather than risking confusion between multiple test situations which may be running at the same time.

As we looked at earlier, these tests are designed to show a ‘fail' outcome initially, and this outcome can come during a running phase or during the compilation phase. In the running phase of the code, the developer can set conditions that have to be fulfilled during its execution, noting what the outcome is and acting accordingly.

Each test has to be judged on its merits, rather than considering it in conjunction with earlier unit tests. Because of this, a complex piece of coding will have numerous tests added to it during this test-driven development phase.


Source: Slideshare

3. Refine The Code

With the series of individual tests now carried out successfully, the developer can move on to the next phase of the TDD process: refining and fixing the code. This all-important phase allows the developer to create functions that pass the original tests, meaning that the code itself is robust and fully functioning.

In this process of writing, testing and fixing the developer is creating a software CI (Continuous Integration) process. Continuous Integration can be used throughout many business departments and processes, but particularly in research and development, and it fits perfectly with a TDD strategy.

This fixing stage of TDD is known as refactoring, and it has to be carried out for each individual test that has been created. It's another key element of successful test-driven development: thoroughness. The focus this places upon the developer, rather than upon automated testing for example, makes it much less likely that errors will remain in place, as the code as a whole is checked and verified by a human, rather than by computer.


Source: FortySeven

4. Repeat The Process

The thoroughness inherent within the TDD process may initially add a little time onto the development schedule. Eventually, however, it is likely to save considerable time, because of its efficiency in analysing, discovering and rooting out errors.

Once the process as a whole has been completed, it's time to run the testing again. This time, it should return positive results rather than failures. As this test process has now completed its task, the developer can now refactor the code again. This gives them a chance to clean up the code so that it's easier to understand for others who will look at it, creating a more elegant piece of work.

How to Make The Most of a Test-Driven Development Strategy

These four stages are the framework on which our earlier traffic light system is hung. The code has been tested, corrected and refined, so the developer can be confident that it meets all their target requirements and will continue to function correctly in future.

It may be that the developer will not be writing all of the code themselves, but creating bespoke sections that will be added to existing work. Alternatively, it may be that they will be working alongside an external development team.

The developer in these instances need only carry out a test-driven development process on the code they themselves have created. Code already in existence should have been fully tested beforehand, and external teams should know of their requirement to undertake thorough testing themselves or to outsource software testing to experts in the field.

Development Testing That Delivers

High quality code can drive our businesses forward, whatever size they are, and a well planned and executed test-driven development strategy can deliver just that. By utilizing a TDD policy, companies gain benefits in three key areas: speed, performance, and scalability.


Source: FSD

By reducing or eliminating errors in future, and the downtime and repair time that follows, companies can make significant time savings on an ongoing basis. A recent report by Gartner found that downtime costs businesses an average of $3,600 a minute. This varies depending on the size of the company, but it's certainly a cost to be avoided.

The extensive testing involved in the TDD process also helps to ensure that projects are delivered on time, without unexpected delays and errors pushing them over schedule and over budget.

The four stage process involved in a TDD strategy also typically leads to high quality code being created. The refining and refactoring stage makes the code easy to read and understand, which is great news if you want to add to the code at a later date.

This touches upon a further advantage of the TDD process: the perfectly functioning code can be easily scaled up if needed, and the testing process already in place is also easy to replicate.

It's little surprise that more and more developers are becoming devotees of the test-driven development process. The more accurate and reliable code it delivers is great for their project, and for their reputation.



Felix Zoot Billson - Head of Marketing, Global App Testing

Felix Zoot Billson

Felix Zoot Billson is the Head of Marketing for Global App Testing, a best-in-class crowdtesting company that is founded on speed, impact and effort. Felix has become adept at growing businesses by focusing on creating optimized customer experiences to maximize business impact and revenue. On the weekends, you'll find him reading his favorite novels and mountain biking. Here is his LinkedIn.

Published Wednesday, July 07, 2021 7:32 AM by David Marshall
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