Behaviour Driven Development in a nutshell

If you’re new to Behaviour Driven Development (BDD) and don’t understand the jargon surrounding it, this is the article for you. This article will explain the most fundamental concepts as well as the basic implementation of this agile methodology.

Let’s start by clearing up the misconceptions. BDD is not limited to test automation and it is not about tools. Fundamentally, BDD is actually about great communication, where an application is specified and designed by describing in detail how it should behave to an outside observer. In other words, BDD is about working in collaboration to achieve a shared level of understanding where everyone is on the same page. That’s the basic understanding you need to know. Easy enough.

So, what does this ‘great communication’ mean for software development?

Great communication means:

  • A usable product first time round, which allows you to get your product to market faster
  • A lower defect rate and higher overall quality
  • A workflow that allows for rapid change to your software
  • A very efficient and highly productive team

How is it done?

Meet our key stakeholders/teams:

Developers • Testers/QA • Project Manager/Scrum Master • Product Owners/BA


To illustrate what happens when you implement BDD, here are the before and after scenarios:

Before implementing BDD

Traditionally, software is designed in a waterfall approach where each stage happens in isolation and is then passed along to the next team. Think conveyor belt factory style:

  1. First the Business Analyst defines requirements
  2. Then the development team work on these requirements and sends for testing
  3. Then testing discovers lots of bugs and sends back to the development team
  4. Things are miscommunicated in transit so repeat steps 2 and 3 back and forth until you run out of time or budget
  5. Release software

The problem here is that everyone is in isolation, interpreting the requirements differently along the way. By the time code is handed in for release, resources are drained, and people are frustrated as there are issues that could have been avoided had everyone just been working together initially.

After implementing BDD

  1. Business and PO/BA have a set of requirements ready to implement
  2. BA, Developers & QA work collaboratively to refine these requirements by defining the behaviour of the software together. Thinking from the point of view of the user, they create detailed user stories. Throughout this process they address the business value of each user story and potential issues relating to QA that may crop up
  3. Each story is given an estimate of how complex it would be to implement
  4. The whole team now has a strong shared understanding of the behaviour of the software and when it will be considered complete
  5. Begin Sprint: Developers & QA then work together or in parallel to produce a product that is ready for release




This process saves time and money and is incredibly efficient. The core element of this efficiency is the team’s clear understanding of scope and what the fundamental features and behaviours required are. Because of the collaborative nature of BDD, issues are brought to light that otherwise would be an afterthought. For example, how a feature might behave differently on mobile or how a feature might deal with a large number of users. These are considerations that should be addressed from the outset.

What is the best way to implement BDD?

Just because people are in the same room or present at the same meeting doesn’t mean they will collaborate effectively. Each of the stakeholders play a crucial role and some teams/individuals may need to change their way of doing things to make sure that collaboration actually happens. The image below outlines the key deliverables for everyone involved when adopting BDD:




An example of BDD in practice

BDD is a risk-based approach to software development; it mitigates the likelihood of running into issues at crucial times. Teams at ECS Digital have been using the BDD process effectively, including  implementing a website feature for a popular media client. The client wanted to create a swipe feature where more mobile users could swipe to see different articles and move through the sections easily. Everyone was collaborating from the initial stages and the team was able to ensure high quality on the website throughout the process of implementation.

With a clear and shared definition of what the website would be like when completed, they were able to innovate further to mitigate the risk involved. They decided that during times of low traffic they would send users to the new website with the new swipe feature and get feedback. Then during risky times of high traffic users would have the usual website without the new feature. This allowed the team to ensure that when they made the feature a permanent part of the entire website they were taking as little risk as possible.

If this team was not utilising BDD techniques by defining the website’s behaviour in detail and involving each team in the development of requirements, they may have released the feature without such precautionary measures or run into many issues when approaching the release date.

If you’re interested in understanding more about BDD and delving into some of the jargon surrounding it – “gherkin syntax”, “the three amigos”, “impact mapping” & “living documentation” – read our previous article here: Behaviour Driven Development: It’s More Than Just Testing

Kouros AliabadiBehaviour Driven Development in a nutshell