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Test-Driven Development: A complete guide

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Test-Driven Development: A complete guide

Developers and businesses across the globe have long been using test-driven development (TDD) to build their applications, and the trend has only been growing in popularity in recent years. But what exactly is TDD? And why should you be using it? In this blog post, we’ll be taking a look at how TDD works, why it’s important, and why every developer should be doing it if they aren’t already.

What Is Test-Driven Development?

Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle. In TDD, developers write new code only when an automated test has failed. This prevents bugs from being introduced into the code and saves time in the long run.

Benefits of Test-Driven Development

1. Helps ensure code quality and catches errors early on

2. Makes code more modular and easier to understand

3. Helps you think through the design of your code before you write it

4. Helps prevent feature creep by forcing you to think about what you need to implement before you start coding

5. Makes refactoring easier and less risky

6. Can improve team communication and collaboration

7. Can help reduce the overall development time

8. Why do TDDs cost less than siloed approaches? Adding new code to the base doesn’t break the base when developers add new code.

9. In TDD, the “keep it green” mantra means the test result must always be green before submitting code to the base (where it affects others). If it isn’t green, the developer works on it until it passes the test.

10. When QA finds a bug in a silo approach, coders have already moved on to the next feature. Finding the bugs later can have downstream consequences. Later developed code that relies on problematic code may also need reworking.

11. The code is documented by tests, which is another benefit of testing. It’s easy to validate the correct working of a program when you read a test, because you understand what it should do.

Software Testing vs. Quality Assurance

Software testing is a process that assesses the quality of a software program. On the other hand, quality assurance is a process that ensures that the software meets all the requirements. TDD is a development methodology which combines these two processes into one. In TDD, developers write tests first, and then code to pass those tests. This helps ensure that the code they write is high quality and meets all the requirements.

The Rise Of Machine Learning Testing

In the early days of software development, the waterfall model was king. But as time went on, agile methodology began to take over. And with that, the rise of test-driven development (TDD). TDD is a process in which tests are written before code is written. This might sound counterintuitive, but it actually helps developers think through their code before they write it, leading to fewer errors. Plus, it helps ensure that your code is actually doing what it’s supposed to be doing. If you’re not already using TDD in your development process, you should be!

Stages of Testing

1. Test first, code second. This is the most important rule of TDD. By writing a test before you write the code that is supposed to pass the test, you force yourself to think about what the code should do before you write it. This helps prevent errors and makes your code more robust.

2. Write a failing test. This seems counterintuitive, but it’s actually essential to the TDD process. By writing a test that fails, you ensure that your code is actually doing what you want it to do when it passes the test.

3. Write the code to make the test pass. This is where you finally write the code that will make your test pass.

Tips on getting started with Test-Driven Development

1. Understand what test-driven development is and why you should be doing it.

2. Write a failing test first.

3. Write the code to make the test pass.

4. Refactor your code as needed.

5. Repeat steps 2-4 until all desired functionality is complete.

6. Review your code and tests to ensure everything is working as intended.

7. Refactor your code one last time, if needed, before deployment

Developers’ arguments about Test-Driven Development

Testing is at the forefront of people’s minds during product architecture, design, and development. Software developers specify up front what to test and how to test it. How can the feature (code) be considered complete and good if it passes the tests?

Before coding a feature, developers write these tests one at a time, starting with a simple case and building complexity from there. This enables developers to ensure that every possible scenario is covered. A developer must pass both the old and new tests before committing a feature to the codebase.

What are the differences between TDD and earlier options?

In the days before TDD, developers wrote code and QA wrote tests. Even within a single team, developers used different criteria to decide when to commit code to the base. Some felt testing was completely the responsibility of the QA team. However, some developers wanted to test their code before sending it to QA. They decided how much testing to do (or not to do).

This led to inconsistent quality coming out of development, resulting in extensive rework, which affected schedules and budgets.

Critics viewpoint of Test-Driven Development

It is perceived by some critics that TDD takes longer and they worry about how that will affect the schedule for releasing new functionality.

It’s true that TDD requires more time when building features. Software developers now have additional code (tests) to create and maintain. However, executives benefit from taking the long view. By spending a little longer on the front end of the SDLC, the entire SDLC can be significantly shortened. Furthermore, TDD can improve the quality of software releases, resulting in higher customer satisfaction and revenue.

Developing complex products may also require writing additional proprietary frameworks to test how the product interacts with third-party tools and utilities. In the case of a utility that you’ve customized in a specific way, you’ll have to conduct tests to make sure your product takes advantage of the utility correctly.

Hurdles to adopt TDD

  • The biggest obstacles to adoption are engineering culture, developer preferences, and the pressure to get products to market quickly.
  • Change management experts can assess an engineering team’s openness to TDD, areas of resistance, and concerns in order to identify areas for improvement. Some developers feel that testing isn’t their job. Their real strength is creating new stuff, and they don’t want to spend their time writing tests.”
  • TDD can be difficult for some managers, who feel it will slow their team’s velocity. They want a high-quality, reliable product but are sometimes willing to take shortcuts in order to get a release out.
  • TDD cannot become successful if management persists with elitist and speed-at-all-costs attitudes. Engineering leaders must set the expectation that all developers, even architects, are responsible for testing and code quality. Training can help all team members get on the same page and establish the ground rules for testing that every member must follow. If the architect is writing the production code, then they are writing the tests.
  • TDD is also sometimes asked how to implement it on legacy projects. Start with the new features if this is the case. When refactoring portions of the legacy code, test the newly refactored segments.

Use of TDD where human options are limited

Preflight checklists are used by airline pilots to keep them from overlooking or forgetting something. TDD serves a similar purpose.

Prior to TDD, a developer would manually test their code and deem it working, before submitting it to the code base. Though the problem might not have been a physical mistake, an underlining detail was likely missed. The code had to be rejected because it messed up the base or prevented other features from working properly. Different instances cause the code to execute differently, and this behavior doesn’t take long before developers can’t remember every code situation and need to employ commenting to track their reasoning. If there are many members in the team, no one can keep track of every interaction in the code.

In TDD, all tests, new and old, are run on new code. Some of the tests may interact with the new code, but most of them will not. With TDD, developers no longer need to keep this information in their heads which lessens the chance of human error.

A green test means the developer knows he or she didn’t break anything, and that the old and new functions work as expected.

Resources to learn more about software testing in general

There are many resources available to learn more about software testing in general. The Software Testing Club website is a great starting point. This website provides articles, forums, and other resources to help you get started with learning about software testing.

Another great resource is the online course Learn Enough Action to Be Dangerous. This course covers the basics of test-driven development and how to get started with writing tests.

If you want to dive deeper into the world of software testing, consider reading books such as Clean Code: A Handbook of Agile Software Craftsmanship, The Art of Software Testing, or Exploring Requirements: Quality Before Design. These books will provide you with a solid foundation on which to build your knowledge of software testing.


In a world where technology is constantly changing and advancing, it’s more important than ever to make sure that your code is stable and reliable. Test-driven development is a methodology that can help you do just that. By writing tests first, you can ensure that your code meets your expectations and requirements. Plus, TDD can help you catch errors early on before they have a chance to cause problems down the road. If you’re not already doing TDD, I urge you to give it a try. It just might make all the difference in the quality of your code.

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