What Is BDD (Behavior Driven Development)? Meaning, Process, and Examples
Behavior-driven development helps develop user-centric products by documenting and designing per the user’s expectations and interactions with the product.
Behavior-driven software development (BDD) is defined as a process that focuses on user requirements and expectations, facilitating collaboration among developers, testers, and project managers. Here’s a definitive guide to the behavior-driven development process with apt examples.
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What Is BDD (Behavior Driven Development)?
BDD (behavior-driven development) is a software development process based on the Agile methodology. The concept of behavior-driven development originated from the test-driven development (TDD) approach. This software development process is focused on end-user requirements and their interactions with the product.
BDD Process Explained
How well the core features of an application will work for end users, how overall application behavior will be to users, and what the audience feedback is while interacting with the application– all these factors are considered while building a product with the behavior-driven development approach.
Behavior-driven development is a highly sought-after software development methodology used for diverse application development for various sectors, from B2B to SaaS. Behavior-driven development is based on three pillars: discovery, formulation, and automation.
Let’s look at why behavior-driven development is so popular among developers and testers alike.
Key advantages of BDD
The concept behind BDD is to enable developers, testers, and business stakeholders to clearly understand an application’s behavior and ensure collaboration between technical and non-technical teams.
Key Advantages of BDD
Even beyond that, there are certain other advantages, which are listed below:
1. Customer-driven product development
By considering customers’ feedback early and adopting the Agile methodology, behavior-driven development ensures a highly efficient and customer-driven product that not only meets but exceeds customer requirements.
2. Proper prioritization of features
Prioritization of product features plays a crucial role in software development. For instance, critical features of a music streaming app are video/audio streaming quality, device compatibility, and user controls, to name a few.
Similarly, core features exist for every product that determines how effective the product will be in delivering what it promises. In the behavior-driven development approach, one can emphasize core product features, prioritize them, and segregate them as per requirements.
Features that offer more business-critical solutions can be implemented, tested, and delivered first. This also helps in time, cost, and resource optimization while improving product quality.
3. Greater transparency
Transparency is the key to success for any product development approach, especially if a collaborative stance is taken. Behavior-driven development ensures greater visibility of the system features so that all the developers, testers, business stakeholders, and other team members can clearly understand what is being developed and whether the features can match the specific set of requirements or not. As a result, greater transparency can be maintained during product development, and one can avoid the chances of ambiguities or conflicts.
4. Reduced maintenance and project risk
For any product development, certain risks are involved, such as the chances of inefficient feature development, product features failure, compatibility issues, redevelopment costs and time, and others. By opting for a behavior-driven development approach, organizations can minimize the risks associated with software development.
5. Better alignment with overall business goals
As this development approach emphasizes the behavior of each feature, details about what purpose they serve, how well it fits in the current market, how it can drive more profits, etc., can be conveyed better. As a result, developing a product that matches business criteria becomes easier.
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Behavior-Driven Development Process
The behavior-driven development process is based on three critical approaches:
1. Test-first approach
The test-first approach is focused on testing the product at the right time to ensure how efficient it is in real-time. It requires the agility of the development, testing, and project teams as well as clarity regarding the technical process, principles, and methods adopted during various project development phases.
The test-first approach eliminates traditional development and testing limitations, where many loopholes or issues get noticed after the product’s final launch. This is why the test-first approach is considered one of the critical approaches in behavior-driven development.
2. Agile testing approach
One of the critical factors that distinguish behavior-driven development from the other conventional development methods is its unique testing approach. Instead of following the traditional build, test, and fix errors procedure, it focuses on Agile testing. Agile testing is based on the famous iterative development and testing methodology where particular emphasis is put on the collaboration between customers and teams.
As a result, customers’ perspectives are considered during the development and testing process. Agile testing is a prime approach in the behavior-driven development process since not only does it build its foundation but helps optimize time, cost, and resources and shortens the feedback response time while minimizing the requirement for documentation.
3. Built-in quality approach
Behavior-driven development adheres to a built-in quality approach, which ensures that the end product has all the required features and solutions and fits the current market. It is not enough to have a set of features and solutions; but it should be market-driven and customer-centric. Behavior-driven development looks after this aspect by ensuring competitive product development that accommodates every requirement of end users.
Now let’s talk about the stages of behavior-driven development. BDD mainly involves three phases: discovery, formulation, and automation.
Let’s delve deeper to know how each of these phases works.
1. Discovery phase
The discovery phase is the first phase of behavior-driven development, where the acceptance criteria are researched and decided. Generally, the product manager actively participates in behavior-driven development’s discovery phase.
In this stage, the acceptance criteria are crafted based on product type, key features, target audience, present market, and other factors. Other team members, such as the project manager, developer, tester, or operation team, contribute with their input. Overall, the discovery phase of behavior-driven development requires the collaborative efforts of team members to come up with the acceptance criteria.
2. Formulation phase
The formulation phase comes into play after the discovery phase is over and the implementation phase is about to begin. The formulation phase is mainly relevant when a backlog item is just about to get implemented. The primary purpose of this phase is to ensure that the acceptance criteria are confirmed and ready to be applied in real-time. Acceptance tests in the formulation phase execute this part.
The purpose of acceptance testing is to run quality assurance methods to determine whether an application or product is as per the requirements. It decides to what extent or degree you can accept a product based on end-user needs and approval. As such, the formulation phase is dedicated to turning the initial acceptance criteria into a stable version with less ambiguity or flaws.
3. Automation phase
As the name suggests, the automation phase automates the process of acceptance tests. It optimizes the time taken and resources used while ensuring that the required outputs are obtained, and criteria are matched. In this phase of BDD, acceptance tests get automated and run continuously to validate and ensure that the new patterns or behaviors are compatible with the system.
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Behavior-Driven Development Examples
Behavior-driven development can define the characteristics or behavior of each product feature through relevant examples. Defining the features with examples takes place before the development process and acts as the acceptance criteria. Here are a few examples of how one can use behavior-driven development differently and with various tools, frameworks, and syntaxes.
1. BDD with Gherkin syntax
The Gherkin syntax consists of a set of lines called steps and comes with an additional structure dedicated to offering a simple learning curve even to non-technical persons and non-programmers. The rest and the central part of the Gherkin syntax are in the form of plain text.
The main focus of the Gherkin syntax is not only to highlight the specific intention of an example and test but to use an accurate description to portray fundamental business rules. Some of the most prominent examples of behavior-driven development with Gherkin syntax are used with the following keywords:
- Feature: It is used to describe a software feature.
- Scenario: This denotes the behavior of the system. A scenario describes various patterns such as events, required results, initial context, and others.
- Background: The background refers to the context and background of the system with a specific set of features and solutions.
- Scenario Outline: The scenario outline implies the outline of the system behavior, especially in the case of multiple scenarios.
- Examples: Examples denote various factors relevant to BDD, such as features, solutions, functionalities, and others.
- Given, When, Then, and But (Steps): These denote various steps, conditions, and relations between the steps.
- “”” (Doc Strings): Denotes strings of documents.
- | (Data Tables): Represents data stored in tables.
- @ (Tags): These refer to various elements of the behavior-driven development process.
- # (Comments): Comments convey essential and additional information relevant to behavior-driven programming.
2. BDD with Cucumber
Another prominent example of BDD can be seen with the testing framework Cucumber. Cucumber is a widely used testing framework that is written in Ruby. Being open-source and straightforward to understand, Cucumber is used widely by developers and testers.
It supports behavior-driven development fully and lets you write diverse test cases easily. You can outline, define, and document the behavior of an application in simple text, language, and syntax called Gherkin, as discussed above.
One of the most significant advantages of implementing behavior-driven development with Cucumber is that it can test code of behavior-driven development written in different languages such as Java, C#, and Python, to name a few. Another perk of using Cucumber in behavior-driven development is that it supports the collaborative approach taken in the BDD process.
For instance, if a higher number of teams and their respective opinions exist during behavior-driven development, Cucumber is used. Furthermore, Cucumber acts as an all-in-one framework for test automation, development aid, and behavior-driven development documentation.
3. BDD with SpecFlow
Another typical example of BDD is observed when it is used with SpecFlow, a prevalent behavior-driven development framework for .NET. While several similarities between SpecFlow and Cucumber exist, this is based on Ruby on Rails and hosted on GitHub.
It is also an open-source framework and not only caters to behavior-driven development and acceptance test driver development, more commonly known as ATDD. Acceptance test driver development facilitates the collaborative efforts of team members and mainly involves four phases:
- Discuss: This is the initial phase or the stage of the ATDD cycle where the initial discussion among stakeholders occurs.
- Distill: In this stage of the ATDD cycle, the Agile methodology is applied to implement testing automation and proper test execution throughout the project.
- Develop: The development phase of the ATDD cycle works on a test first development or TFD approach, which implies that the test is first run, then the bugs or issues are pointed out, and finally, the process is executed for faster and error-free development.
- Demo: In this phase, the team provides a demo to the stakeholders to convey the tests run, the results, and issues or bugs to be fixed, if any.
While BDD and ATDD are used on a large scale with similar tools/frameworks, they differ in one main factor. ATDD focuses more on the specific requirements to be fulfilled, while BDD emphasizes the behavioral aspects of the features. Understanding both ATDD and BDD is recommended to unleash the potential of SpecFlow used in BDD.
Like Cucumber, SpecFlow also offers a simple learning curve and lets the teams document the behavior and properties of the system features in simple English language. Since it supports the collaborative approach taken in BDD, it is another popular choice for behavior-driven developers. SpecFlow also lets you document the feature specifications in Gherkin format.
SpecFlow/Cucumber BDD test: Real-life example:
Here’s a glimpse of how the SpecFlow/Cucumber BDD test will look for an application or system’s feature ‘Log In’.
Feature: Log In
Log in must be fast and user-friendly
Scenario: Successful Log In
User should get a pop-up message of ‘Signed In’ on screen
Given the user has chosen to sign up
When the user sign up with the valid credentials
Then they should receive a pop up message
Scenario: Invalid Credentials
When a user tries to log in using the credentials which don’t exist.
Scenario: Invalid Password
When a user puts invalid password
This helps visualize the whole system feature and its behavior under different conditions. It also aids the collaborative approach taken in behavior-driven development as it is easily understandable by various teams, businesses, and stakeholders.
4. BDD for impact mapping
Impact mapping refers to developing a graphic strategy to determine a product’s core and additional features, which are the most important and apt for a product. Impact mapping is crucial and must be executed at the beginning of any product development. It is one of the critical use cases or examples where BDD is widely used.
As discussed above, BDD is pivotal for describing a product’s features and is applicable in impact mapping. One of the common issues during product development is trying to add too many features to meet the end goal or criteria. Often, this leads to excessive spending of time, money, and effort, and the product ends up with redundant features.
The best practice for product development is not developing too many features but building the core features so they can deliver the required solution to end users. That’s why BDD in impact mapping is relevant for developing various products.
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Takeaway
The behavioral development approach stands out by letting one think and build from a customer’s viewpoint. Instead of simply developing a set of features, it focuses on the characteristics that can be a good fit for real-time applications and use cases.
Furthermore, if working in a collaborative approach is your preference, or if you aim to build a customer-centric and market-driven product, behavior-driven development should be your first choice.
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