HomeResoursesAGILEAll About Test-Driven Development: Overview, Phases, Techniques

All About Test-Driven Development: Overview, Phases, Techniques

It is natural for humans to make mistakes during the code and design process when it comes to software development. Feedbacks help with spotting these mistakes. But, when there is a delay in feedback, the changes might be piled on broken code such that it becomes hard to spot the root cause. To address this issue, the best thing developers can do is to use the TDD approach. With Test-Driven Development, it is possible to get immediate notification of mistakes such that bugs can be prevented. Thanks to TDD tools that make using Test-Driven Development easy.

Test-Driven Development – A Basic Understanding:

In the lifecycle of software development, software testing plays a crucial role. During the software development process, it is important for the developers to spot bugs and errors. Only then, they can arrive at the best quality software. It becomes important to pay attention to software testing to improve the quality of the software program. When talking about software development approaches, many such approaches are used. One such approach that has proven its effectiveness in many ways is Test Drive Development or TDD. 

It can be stated that TDD is the key technique for extreme programming. It suggests that the code should be developed or modified completely based on unit testing. It is nothing but a software-driven process that follows a test-first approach. You can understand that when a developer follows the TDD approach for software development, he will first write a fully automated test case. He will do this even before he writes the production code. He will do it for testing and refactoring. In other words, TDD is the practice of writing a test code that fails before writing the code for the intended feature. With the help of the test code, the developer will refine the feature code until it passes the unit test.

Phases of TDD:

Before you choose one of the best Test-Driven Development tools, it is better to first understand the three phases of TDD. 

1. Practice Test Creation: 

In this first phase, the developers will have to create concise unit tests for verification of a particular feature or functionality. When creating practice tests, they will have to ensure that the test complies so that they can execute it. The thing to remember here is that initially, the test will fail. But, this is a failure that is essential as developers create compact tests on the basis of assumptions on how the feature will behave.

2. Code Correction:

Once the test fails, the second phase gets into the picture. At this phase, the developers will have to make minimal modifications needed for rectifying the code such that it can successfully run when it is executed again and does not fail as in the previous phase.

3. Refactoring the Code:

Once the test successfully runs, developers will have to check for possible ways to optimize the code or redundancy so that they can improve the overall performance. But, when refactoring, they should make sure that it does not affect the behavior of the entire program.

You can understand the phases of TDD from the flow chart below:

What Makes TDD Different and Unique from Traditional Testing Techniques?

As mentioned earlier, tools used for Test-Driven Development make testing easier when you follow TDD as against traditional testing methods. However, this is not the only difference. Other differences make TDD special and unique:

  • When you use traditional testing techniques, a successful test will find one or more errors. The same happens with TDD as well. But, in TDD, when the test fails, it is an indication that you are progressing as you know that you should resolve the issue.
  • With TDD, you can make sure that your system meets the needs defined. In other words, you can stay confident about the program you develop with this development and testing technique.
  • In TDD, attention is given to the production code that checks whether testing will work rightly. But, in traditional testing techniques, more attention is given to test case design. 
  • With TDD, it will be possible to achieve complete test coverage. As against traditional testing techniques where the testing is done entirely, in TDD every line of code is tested.
  • The combination of both TDD and traditional testing will focus only on testing against the perfection of the system.
  • In Agile Modeling, you will have to do testing with a purpose. You should be aware of why you are testing something and what level its requirement should be tested.

These features make TDD the best choice even if your organization follows Agile methodology.

What Makes TDD Fitting For Agile Development?

Agile development needs feedback at regular intervals for the development of the expected product or service. This is why Agile Development is referred to as Feedback-Driven Development. These days, the probability of project requirements changing during the development sprint cycle is more. To handle this and to develop products that are properly aligned with the ever-changing requirements of clients, teams need constant feedback to prevent the creation of unusable software. TDD hopes to provide this feedback early on in the development cycle. 

The test-first approach of TDD aids with the mitigation of critical hindrances that hinder the delivery and quality of the product. On the basis of regular feedback, it will be possible for the development teams to fix bugs and even they can add fresh features required then and there. In turn, the solution evolves making sure that everything works as per the client’s expectation. TDD improves collaboration between team members from both the QA and the development teams and even collaboration with clients. Moreover, as the tests are created in advance, teams need not have to spend time with the recreation of extensive test scripts.

For these reasons, organizations that use the Agile framework use TDD.

Test Driven Development Tools:

For the best benefits from TDD, you should be looking for the best tools used for TDD. Here is a list that provides you with knowledge of the common tools used for unit testing. These tools can effectively support test-driven development approach:

JUnit for Unit Tests:

This is a Java-based test driven development tool. In reality, it is a unit test framework. It has been designed to help programmers use Java for developing their software. In the test automation process, unit tests are the smallest element. Using unit tests, the developers will be in a position to check the business logic of any class. This tool can play a crucial role in the development of the TDD framework. It is one of the frameworks that are part of the unit testing frameworks together called Junit.

csUnit and NUnit:

These TDD tools are designed for helping developers using .Net for developing any program or software. Both these tools are open source.


When it comes to automated testing frameworks, Selenium holds a prominent name. This browser-based framework works on many different browsers and operating systems. It even features the Selenium IDE, which is a Firefox and Chrome extension that permits the recording and playback of user communications. 

When it comes to scaling tests, which means trying the test on different systems, Selenium Grid is the best tool. The most familiar tool in the framework is Selenium Webdriver, which is a combination of bindings that are particular to language and permits the creation of browser-based regression tests.


If you look for the best test driven development tools with a rich set of features, you can rely on Mocha. This is a Javascript Test framework with a lot of features that runs on Node.js and in a browser. The interesting thing about this tool is that it makes testing that does not sync fun and simple. The tests run serially when using this tool and it can permit accurate and flexible reporting as well. Also, the interesting part of this tool is that it can map uncaught expectations to the appropriate test cases.

With this tool, you can write specs.js files for your tests. When you work with NodeJS, you can include the script in your package.json file. In turn, you can run your tests regularly.


Apache JMeter might be used for test performance both on dynamic, static resources and dynamic web applications, particularly for performance/load testing. It is advantageous for the stimulation of heavy load on an object, network, server or server for testing its strength and analyzing overall performance under varied load types.


This is a testing framework for Ruby projects. It helps as one of the tools used for test driven development. It aids with paying attention to the documentation and design part of test-driven development.

Other tools:

Here is a list of other tools used for TDD:

  • TestNG: This is yet another testing framework for Java. You might wonder why to use this tool as against JUnit. It is because it overrides the restrictions associated with JUnit. This is an open-source test automation framework for Java. It is a robust framework for its useful set of advanced features as compared to its peers. The letter NG stands for next generation. This very term denotes the value of this tool and its effectiveness as a TDD tool.
  • Pyunit: If you are a developer using Python, this is a standard unit testing framework that can be of great help to you. In TestComplete, you can run Selenium and Python-based unit tests created with PyUnit testing framework. You can do this as a part of your TestComplete project. The best feature of this tool is that it has a PyUnit Test Editor. With this facility, you get the chance to configure the tests that you wish to run.
  • PHPUnit: This tool is ideal for developers using PHP Projects. It is nothing but a collection of utilities including executable files and PHP Classes. Apart from writing tests, this tool will allow you to see the result of the testing process in the form of a graph. In turn, you can understand the quality of your code. 


This is an overview of Test-Driven Development and can help you with the best software development phases and tools that will make your software worthy from the point of view of clients/stakeholders.


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