Introduction
 

Over the last couple of years, the process of software development has moved from following a Waterfall approach to Agile methodology. Since the method of Agile development involves continuous change, the overall testing process has also been altered so that these frequent changes will avoid introducing newer bugs or even breaking the functionality of the entire application. 

Most software developers of today are highly aware of procedures such as Behaviour Driven Development (BDD) or Test-Driven Development (TDD). The actual reality is that – both of these methods have their own merits & demerits. That’s why, to help you understand each technique better and assist you in making a better decision, we will be exploring the significant differences between these methodologies.
 

What Do You Mean By Test-Driven Development (TDD)?
 

TDD can be defined as a type of software development process which involves writing automated test cases before writing the various functional segments of the code. Such a method is highly popular when it comes to Agile methodologies because the process can quickly deliver a shippable product at the Sprint cycle.

The main idea behind TDD is to learn whether the code is valid to be used. If the test code fails, then the main intention would be to modify or even write fresh code, in case the test scenario fails.
 

TDD can be divided into the following few steps:
 

• Based on the needs stated by the requirement documents, the developer first writes an automated test case. 
   
• The whole Development Team then test-runs these automated scripts. Sometimes these tests pass, other times they fail. 
   
• The team then re-factors in the code, so that the test can be able to pass successfully. 
   

Benefits Of TDD
 

• Reduces the total amount of work that might be required for reworking the code. 
• Assists in exploring errors or bugs very fast. 
• Faster feedback is received. 
• Promotes the creation of better & cleaner designs.
• Improves the productivity of the entire Development Team.
• Improves team collaboration and sharing. 
• Enhances the confidence of the entire Development Team.
• Easy to maintain and flexible code is developed.
   

What Do You Mean By Behaviour Driven Development (BDD)?
 

BDD can be defined as a type of software development procedure that helps in defining user behavior before writing the functional elements of the code or even the automation code/scripts. This technique is also utilized during Agile project development, as it can ensure a shippable product at the end of the team Sprint.

Most of the time, the ‘Given-When-Then’ approach is used for writing the test case scenarios. An example for better understanding would be:
 

• Given that the login credentials have been entered successfully by the user.
   
• When the user clicks the login icon.
   
• Then the successful validation message should be displayed.BDD include the following steps:
   
• Firstly, the overall behavior of the user is defined by the Product Owner in a simple language, such as in English. 
   
• It is then converted to automated scripts and thereby run against the functional code. 
   
• Functional code is written by the Development Team to make sure that the automated scripts run successfully. 
   
• Refactoring and organization of the final code are done to deliver the product.
   

Benefits Of BDD
 

• Due to the use of non-technical language, the process can reach a wider audience. 
   
• Always focuses on the way the system should behave, not only from the developer’s perspective but also the customer’s perspective as well. 
   
• It’s highly cost-effective.
   
• Not many efforts are required to verify any defects post-development.
   

TDD vs BDD – The Real Differences
 

1.The Process
 

One of the biggest differences between these two is that – in BDD, you’re simply looking for the behavior. For instance, what will the system go through under a specific condition?

On the other hand, in TDD, you have to perform a test for a method, which will have its own set of conditions. And when the system will evolve, the tests might give you false results.

In a nutshell, in TDD you rarely care about the output because you’re only concerned about running the system in a specific manner. But, in BDD, the way you come up with the output doesn’t matter. The only thing that will matter whether the output is correct with the given condition.
 

2.The Feedback And Communication
 

When it comes to feedback & communication, BDD will have an edge over TDD. As the overall behavior in BDD will be written in a simple, plain, descriptive English Language, clients will be able to understand the test quite well, thereby providing their feedback instantly. As a result, more lines of communication will be opened up during the project development.

The incorporation of useful feedback can further help in the improvement of the design and tests of the software that is being developed.

However, in TDD, only the team of developers will be able to understand the test scenario, which will indeed limit the amount of communication that is to be done. But, it should be realized that this procedure will ultimately deliver a better quality code.
 

3.The Perspective
 

When it comes to perspective, in BDD, the test can be able to satisfy both the customers as well as the developers. On the other side, in TDD, the test will only be able to satisfy the team of developers and the code they create.

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Conclusion
 

By understanding each of the above-mentioned methods and how they function will quickly help developers along with other individuals that are involved in software development, to figure out the best strategy for their use case scenario.

At the end of the day, it should come as no surprise that BDD is simply a better approach than TDD. But, you should never forget that BDD actually has evolved from TDD and therefore eliminate the disadvantages of TDD. Therefore, it’s recommended that developers should implement both methodologies so that they can enjoy the benefits of both procedures while also meeting their specific requirements in the most efficient manner possible.