The Art of Test Driven Development (TDD) for Developing Quality Software

Quick Rundown: Develop high-quality code consistently with Test-driven development (TDD). But how? Read on and discover how this proven methodology works, its benefits, X-factor, and a lot more that can help you revolutionize your development process and deliver tangible results.

Here’s the sob story of every developer - After a long-drawn week of releasing a new product, the development team calls for a celebration. But instead, they all have to desperately find bugs and figure out how to fix them. The support guys are breathing down their necks because the client has eyes on the project.

Such soul-crushing regularity in delivering quality software is not uncommon in the development industry. For example:

• Debugging software takes 620 million developer hours each year, costing around $61 billion.
• Developers spend 10 times more time reading code than writing.
• The average time required to fix a software error is 13 hours.
• The cost of fixing system failures during testing can be 15X more than fixing them during design/implementation.

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But what if we tell you there is a modern technique of agile software development to address these challenges? A rule of thumb so efficient that it virtually eliminates the need for debugging or notifies you about coding errors right after you made them?

Introducing Test Driven Development, where you write tests before the code itself!

What is Test Driven Development?

Remember those days of punch cards when developers had to painfully hand-check each and every line of code to ensure seamless compilation. A compile error meant they must go through an extreme debugging session to find out the mislaid character.

However, compiling code is not a big deal today as IDEs (Integrated Development Environments) provide a fast feedback loop to find and fix errors easily.

TDD does the same by cranking up the feedback on code execution and looking into the syntax as you type. Every few minutes, or even every 20/30 seconds, you can verify that the code is doing what it should do. And if there is an error, you need to check only a few lines of code.

The concept is similar to double-entry bookkeeping. You get to define the same idea twice but in different ways – first with the test and then with the code. Programmers have coded both of them correctly if they match. And if they do not, there is an error somewhere.

Despite everything, TDD in agile is not all about testing. The proposition behind it is that you should continuously test and refactor all code. But those tests are not the whole point of this software development life cycle methodology; the ultimate goal is to achieve three important things by writing tests first and keeping them easy to write:

• Building a safety net to confidently implement changes.
• Designing/redesigning code to be clean, readable, and uncomplicated so that it is easily testable.
• Creating comprehensive specifications with forever-relevant documentation.

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Okay, But What is the Reason to Use TDD?

Yes, there are countless discussions, studies, and arguments on the usefulness of test driven development. And although it would be helpful for you to gather expert insights, we bet they do not have the answer to why you should follow this development approach in the first place.

So, let us give you a simple example and help you get it in a single shot.

Imagine your developer has just completed a small feature in the app. Now, do you think it would be enough to do just manual testing by interacting with the browser? We do not think that is a good decision, which means that part of the code is faulty.

But the scenario is about testing and not the TDD framework, right? So, why use it?

Well, as a brief answer, it is the best and simplest way to maintain code quality and coding standards, as well as effective test coverage. As Kent Beck also said, this development method focuses on the elimination of fear in app development. You need fear to be alive, but when it comes to working with the bare minimum cognition, it can be a killer.

And to elaborate on the answer, we need to walk through how the TDD cycle works and what exactly the process is.

So, How Test-Driven Development in Agile Works?

First up, let us understand the rules as laid out by Uncle Bob (the one and only Robert C Martin):

1. You are not allowed to write any production code unless it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures.
3. You are not allowed to write any more production code than is sufficient to pass the one failing unit test.

These rules are for helping DevOps services providers and dev teams keep things straight in their heads and stay away from rabbit holes. It will also help them focus on all the phases of acceptance test driven development, which are as follows:

• Write the test (Red phase of TDD)

Developers begin this process by writing a test for a particular functionality. Developers must have knowledge about the specifications of the code. The best way is to go through use cases and user stories to grasp the aim of the product.

• Test certainly fails

After writing the test, developers run it. But it will definitely fail since you have no code to implement yet. This ensures that the dynamics of automation testing work perfectly and dismiss the possibility of any new test passing due to defectiveness.

• Write the code (Green phase of TDD)

Now that the developer knows that the functionality works as per the design, it is time to write codes that pass the test. The code might not pass the test perfectly, but it is fine. You do not have to write code except for the specific feature.

• Run tests

As the feature works according to the design, developers can utilize test management tools to redo the test. This confirms that the latest update has not affected the previous functionality.

• Refactor the code (Blue phase of TDD)

TDD best practices demand continuous cleaning of the codebase as it grows. While the last phase focuses on writing the code, this phase comes with efficiency. Developers can add new features and remove duplications.

• Repeat from the start

Repeat the above-mentioned steps each time you work on a new functionality until the cycle covers the whole application.

What are the Benefits of TDD Framework?

Test driven development has proved to be less expensive than any siloed methodology as it helps in adding new code without breaking the base. The mantra is to create green test results before code submission. And if that is not the case, developers do not stop working on the code until it is ready to pass the test.

This results in a range of tangible benefits that help you keep up with the latest software testing and quality assurance trends. In short, TDD gets you:

1. Notifications about early bugs and errors
2. Easy Diagnosis of bugs as pinpointed by the test

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In turn, this boosts your business by:

• Reducing support costs by lowering the number of bugs that find their way into production.
• Minimizing the risk of accidental complications, cutting down the cost of improvements, and keeping the code clean.
• Enhancing the bus factor, leading to optimized onboarding of new team members.
• Maintaining a continuous pace at delivering value-based software solutions.
• Enabling continuous deployment and trunk-based development.

TDD vs BDD: Test Driven and Behavioral Driven Development

While we talk about TDD testing, it is important to shed light on a related vertical called BDD – Behavioral Driven Development. Since both of them are testing methods for different types of application software, these two terms may look and sound similar.

And although both strategies depend on writing the test before writing the code as part of automation testing, there are subtle yet noteworthy differences between them:

• TDD involves a solo developer without any external input, whereas BDD requires collaboration between developers, product managers, and test engineers.
• The TDD methodology focuses on testing individual pieces of a feature in isolation, whereas BDD checks an app’s behavior from a user’s perspective.
• BDD is all about driving results of a higher-level scenario, while TDD delivers the result of a particular procedure.
• TDD works on the code level that executes certain requirements, while BDD works on those app requirements levels.
• TDD has a refactoring stage, whereas BDD does not support refactoring like TDD.

In spite of such minor contrasting points, it is important to note that test and behavioral driven development approaches are not mutually exclusive, as the latter represents an evolution of the former testing strategy.

Getting the Most Out of Test Driven Development: What to Do and What Not to

Like the rest of the software development techniques, TDD unit testing needs you to follow specific rules to benefit from it. Here we provide you with a brief outline of the most critical factors to consider:

Define test criteria – You must establish a clear set of pass/fail parameters for the unit testing and functional testing. This is because you have to ensure that if the test goes well, the feature will work perfectly as well.

Limit the scope – Test driven approach demands the limited scope of each development step as it focuses on a single feature at a time. If the scope is large, developers have to add multiple test cases at once, which might lead to inefficiency.

Use a reliable testing framework – Make sure you are using a sound testing framework/harness. Any failure in the code comes from a failure in the test, not in the framework.

Keep up with existing tests – You must always maintain tests until each unit of the entire app ticks off the quality check. When you make changes to the code, it might cause the failure of previous tests, even if the original code works.

Now that you know how to fully utilize TDD tools, take a look at the ways you can fail at this practice. Here are some of the most common mistakes organizations make:

• Writing more than one test at once.
• Writing tests for insignificant code, like view or accessor without logic.
• Running tests infrequently and missing out on the early feedback loop.
• Not refactoring all the time.
• Writing tests without assertions.
• Writing slow tests. Ideally, it should not take more than a few minutes or even seconds.
• Not following the test-first method.
• Running integration tests using unit tests. Not that it is wrong, but it may slow down the whole process.

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Stop Waiting, Start Going for TDDAs you have understood by now, creating quality software calls for the best of both art and science. Your high performing software development team should have expertise in relevant methodologies to fully demonstrate your idea, and for that, test driven development is a solid mechanism to have on your agenda.However, as simple as it sounds, the reality is often different. TDD implementation needs rigorous practice till you get to the point where the development process is faster with this approach than without it. That is when you can move it from your head to your bones.But despite all the hardship, the ultimate reward is worth it – confidently developing and deploying new applications without the dread for the next release. That is how you can deliver value at an unceasing pace.Hence, shoot your shot. The sooner you take the plunge, the better hold you will get over the process.And we are here to help you with that. At Radixweb, we work our way out through agile testing practices like TDD to build top-quality products at our clients’ disposal. Discover our industry-leading software testing services and take a step towards green, error-free software before bug reports start flooding in.