TDD in Action

This article is a continuation of my previous article where I discussed TDD methodology. In this article, we are going to see TDD in action.

I thought it’s better to demonstrate TDD through a video instead of writing an article. So, here is the video that I recorded to demonstrate the use cases. I hope you will enjoy it and learn something new. Please let me know in comments.

The full source code is available on GitHub.


Introduction to TDD

When you realize the true power of tests for the first time


TDD or Test Driven Development is a development methodology that completely changes the way we develop our code. Although this has drawn some criticism, its still getting more and more popular and TTD is considered as an important skill in many job listings.

TDD forces the developers to write the tests first, even before writing the production code. Wierd, you say. Not really, actually.

Why Tests First?

Why not? I mean, don’t treat your tests as second-class citizens of your project. They are as important as the production code, if not more.

Tests are your weapon, the stronger they are, the more powerful you become. They enable us to understand the code, quickly modify it, and bring down the maintenance cost. Don’t believe me? Take my word for it.

What is the best way to understand any new library or a framework? Even we have well-written docs in good English, what we, as developers, always look for is the “code examples“. This is because we prefer well-written code over well-written sentences.

Our tests are code examples of our production code. The tests tell other developers how to use this code and what scenarios should they consider. This brings down the learning curve.

Test Driven Development

How to do TDD?

In TDD, we start with tests first. Since we are starting with tests, it’s obvious that the test will fail. Then we write the production code just enough to pass the failing test. Once done, write another failing test and the process repeats. This way, we are writing code in very short test/development cycles.

It makes sure that all of our production code is covered with the unit tests, which is a good thing.

Following this process forces the developers to have clear API contracts. They are forced to think how the methods are gonna be used by the outside world. When I say API, I mean any public methods that we expose from our classes.

It automatically makes our code easily testable.

Many would argue against this practice saying that it requires more time, but actually, it doesn’t. Whenever we feel like making any changes to the code, we will be able to do so effortlessly, knowing that the tests have our back. This will save a lot of time. Always remember, the code is going to change, today or tomorrow. And when the time comes, you will bless yourself or the original developer for writing such concrete tests.

Fragile Tests

Ever been in a situation where you modify a small bit of code that results in multiple test failures and you find yourself modifying tiny pieces of code in all the failing tests just to find some other tests failing?

Congratulations, you have discovered fragile tests. Many people find themselves stuck in the loop of fragile tests while following the TDD. But think again, is it really the problem of TDD? Or an advantage of TDD?

Having fragile tests that break every now and then is not the problem with TDD, in fact, its the problem with the tests themselves. TDD or not, bad tests are bad tests. They will keep haunting the developers till they exist.

So how does TDD help in writing effective tests? If you find yourself modifying every test while writing code, it is a signal that our tests need refactoring. It’s better to refactor 10 tests than refactoring 50 tests.


But my teammates are not interested in TDD. But my manager doesn’t approve of TDD. But my architect thinks TDD we are not prepared for TDD. But, but, but…

This will never end. Understand that explaining the benefits to the team is our responsibility. We need to make them understand that this is the correct way. Even then if no one listens to you, we can still follow the practice on our own.

It is up to the individual whether to follow TDD. Our managers need not worry about the methodology if your performance is good. It’s an individual’s practice.

The next article/video shows you how to actually write code using TDD methodology. See it in action.

If you are just starting with Java or are confused with terms like Java SE and Core Java, head on to this article to simplify things.

Starting Java Development Career

Starting a Java development career can be a great choice given the number of job openings that pops up day after day. Java has been around for a while and there are a tremendous amount of companies that already have a Java system in place. This only means a lot of development opportunities.

Java is compiled, type-safe, and fast. I mean really fast. I have myself migrated a fairly complex project from Python to Java and another one extremely complex system from .Net to Java. The main reasons were performance improvement and platform independence.

Learning Java in itself is not that difficult, but in order to become job-ready and be able to develop real-world Java applications requires a fair amount of knowledge. In this post, we’re gonna list down the skills required for becoming a job-ready Java developer.

Core Java

Core Java or Java SE is the starting point of your Java development career. Many beginners think that once they learn Java SE, they are ready to develop real-world applications. This is not true. First of all, in order to be a good programmer, learning the syntax is not enough. You should learn how to design an application by using various constructs provided by the programming language. You need to master it by writing a lot of code and developing some projects keeping the design principles in mind.

Next thing is that Java SE itself is not enough. A quite common application would be to develop a command line application which has limited use. To get to the next level, you need to learn Java EE or Advanced Java.

Advanced Java

Java EE or Advanced Java supports the development of server-side backend web applications. While an understanding of Java EE concepts like servlets, JSPs, and EJBs is useful, you need not master this. Just the basic level of knowledge should be sufficient.

The main reason for this is that developing any web application by simply using Java EE is difficult and time-consuming. There are a lot of frameworks available today that help in this development. Some of them are Spring, Spark Java, and Dropwizard.

These frameworks make web application development so easy that you don’t even need to know about JSP and Servlets in order to develop a basic web application.

If you are not sure which framework you should use, go for Spring. Its the most widely used framework and has a very active community.


Testing is an integral part of Software development. Writing automated unit tests helps developer receive instant feedback on the code. Unfortunately, many developers consider tests as second-class citizens.

The de-facto for unit tests in Java is Junit. Junit is widely used and has a great community out there. I can’t stress less on the importance of tests. You just need to master it.


Before you start with any framework, you must be familiar with some build tools and IDE that makes your job easy.

Build Tools

A Java application can consist of lots and lots of files and one big project might be divided into smaller modules where one module is dependent on another. Apart from this, your code might be using some popular libraries like apache commons to solve some well-known problems that come with every project.

These dependencies need to be supplied from your development environment to test environment and then to the production. This can become a daunting task if done manually. To solve this problem, we use build tools like Maven or Gradle.

If you are unsure of what to start with, choose Maven. It’s the older among the two, has wide applications, good community support, and easier to begin with.


An IDE or Integrated Development Environment helps you a lot. It saves you a lot of headache by providing the features like real-time compilation – see the compilation errors as you type, no need to wait till actual compilation happens. An IDE provides type completion among other things.

Code completion
Code completion example

There are a lot of IDEs available but only two of them are really good. My preference is IntelliJ Idea and then Eclipse.

I use Ultimate edition of IntelliJ which is paid, but there is Community edition which is free. Eclipse is also a free IDE. There is another IDE called STS (Spring Tool Suite) which is essentially Eclipse with plugins for Spring development.


Git is a distributed VCS (version control system). Every project uses one or the other VCS for source code management. Git keeps different versions of the source code files as you modify them. Making tracking changes and code history a manageable task.


A web application needs to be deployed on a server. There are several choices like Tomcat, Jetty, GlassFish. A beginner should start with Tomcat. It’s really lightweight and very easy to configure and use. However, if you are going to develop your first web application using Spring Boot, then there is no need to worry about servers for a small project. Spring Boot allows you to use an embedded server.


In essence, if you want to get a job as a Java developer, you need to learn about Java Development along with the most popular frameworks and tools. Using a popular framework will increase your chances of employability as well as it will be easier for you to learn.

So once you get hold of Java SE, develop some small projects to get hold of the language. Then Start learning Spring Boot + Maven and use STS for development. Once you are familiar, develop more and more web applications.

You might want to check out the resume polishing tips before applying for a job. All the best.