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Showing posts with label BDD. Show all posts
Showing posts with label BDD. Show all posts

Sunday, September 7, 2014

What is the difference between Test Driven development and Acceptance Test Driven development?

Test driven development (TDD) and Acceptance Test Driven Development (ATDD) are related to each other. TDD is a developer’s best tool for helping in creating properly written code units i.e., modules, classes and functions, that carry out the desired function properly. On the other side, ATDD acts as a tool for communication between the developers, testers and the customers to define requirements. Another difference between TDD and ATDD is that the former requires test automation while ATDD does not. But ATDD might require automated regression testing. The tests written for ATDD can be used for deriving tests for TDD. This is so because a part of the requirement is implemented in the code. It is important that the tests must be readable by the customers, but it is not required for TDD tests.
TDD involves writing the test cases and making them fail before the code is written. Next enough code is written to make the tests pass and then refactor it as per the requirements. The tests must pass after it. The primary focus of TDD is on methods and single classes i.e., the low level functionality. This leads to much flexible code. Now what is the need for ATDD? The reason is that the TDD just tells you that your code is fine but it doesn’t tell you why that piece of code is even required. However, in ATDD, in the early stages of the software development process itself the acceptance criteria are stated. In the succeeding stages of development process this criteria is used for guiding the development. ATDD is more like a collaborative activity engaging everyone from developers and testers to business analysts and product owners. It ensures the implementation process is understood by everyone involved in the development process.
There is a third thing called the BDD or the behaviour driven development. This one is quite similar to TDD except that we call tests as specs. The focus of the BDD is on system’s behaviour rather than its implementation details. It also focuses on the interactions taking place in software development. Developers following this approach make use of two languages i.e., the domain language and their native language. TDD consists of unit tests while ATDD uses acceptance tests. Plus, the focus is on high level. BDD is required for making the product more focussed on customer. BDD allows the collaboration of developers with other stakeholders easy. Using TDD techniques and tools requires technical skills because you have to know the details of the object. Non – technical stakeholders would be lost while following the unit tests of TDD. BDD provides a clearer view of the purpose of the system. TDD provides this view to the developers.
The result of the methodology of ATDD is entirely based up on the communication that takes place between the developers, testers and their customers. A number of practices are involved in ATDD such as Behavior driven testing, specification by example, story test – driven development, example – driven development and so on. With these processes, the developers are able to understand the needs of the customers before the actual implementation. The difference between TDD and ATDD arises because of the latter’s emphasis on the collaboration between the three i.e., developers, testers and customers. The acceptance testing is encompassed in ATDD but in one way it is similar to TDD i.e., it insists on writing the tests before coding can be started. These tests provide an external view of the system from the point of view of a user.


Thursday, January 17, 2013

What is meant by Behavior Driven Development (BDD)?


BDD or Behavior Driven Development is one of the most important development approaches in the field of software engineering and is just a modified implementation of the TDD or test driven development. It actually combines the guiding principles and general techniques of the test driven development with the combined ideas from two sources namely:
  1. Domain – driven design
  2. Object – oriented analysis and design
- The behavior driven development thus provides a shared process and tools to business analysts and software developers for their collaboration on the software development process.
- Ideally, behavior driven development represents an idea regarding the management of the software development process by both technical sight and business interests.
- It is assumed in this approach that the specialized software tools are being used to provide support to the development process. 
- The specialized tools thus involved have been developed especially to be used in projects following the BDD approach. 
- They can be considered as special tools that supports test driven development. 
- The primary purpose of these tools is to automate the ubiquitous language statements around which the BDD process is centralized. 
- Agile software development gets successful only when it is considered from the beginning. 
- On the contrast, in some projects this is the last thing to be considered which means that there is no sustainable operation in the websites that serve purposes other than blogging.
-  A blogging web site is just a software that is just modified by the users as it is ready for use. 
- However, BDD and TDD provides the only ways for achieving this goal. 
- The word ‘driven’ in TDD signifies that the test cases are written first and then the code for passing the test. 
- TDD is actually a low level methodology of accomplishing tasks and is sort of developer oriented. 
- On the other hand in BDD, the description of the tests is written in a natural language, thus making the tests more accessible to people outside the development team. 
- Such descriptions can describe the functionality in the same way as done by the specifications. 
Dan North was the person who actually brought the concept of behavior driven development in response to the issues experienced in implementing the test driven development such as:
  1. From where to start testing?
  2. What is to be tested?
  3. How much should be tested in one turn?
  4. How the reason for the failure of the test is to be understood?
- At the heart of the behavior driven development approach lies the approach to acceptance testing and unit testing which were again identified by North. 
- He emphasized that the acceptance tests should be written using the user story frame work. 
- Thus starting from the scratch, the development of the BDD approach continued over a couple of years and finally we have it as a communication and collaboration framework. 
- It has been designed especially for the QA people and business participants involved in a project.
- The agile specifications, BDD and testing eXchange meet highlighted the following characteristics of BDD:
  1. Second generation methodology
  2. Outside – in approach
  3. Pull based
  4. Multiple stake holder support
  5. Multiple scale generation
  6. High automation process
  7. Agile methodology
- Further, it was said that it involves a cycle of interactions with outputs that are well defined and results in delivery of working software that makes sense. - First, BDD frame work that came in to existence was Jbehave which was followed by Rbehave–a story level BDD ruby frame work.
- All these frameworks were later replaced by cucumber testing tool. It was developed by Aslak Hellesoy. 


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