What is BDD? Use, Benefits, Challenges & Examples

Behavior-driven development (BDD) is an Agile software development method that focuses on improved collaboration between developers, testers, project owners, and business stakeholders to define how a system should behave. It encourages writing tests in natural language that non-technical team members can understand, ensuring that everyone is aligned on established requirements.

Dan North, the creator of the BDD methodology, observed that his students and colleagues often struggled to understand the purpose and language of TDD. 

To address this issue, he introduced BDD as an evolution of test-driven development (TDD)—shifting the focus from testing implementation details to defining system behavior through examples. Instead of writing low-level unit tests, teams use plain-language scenarios that describe how features should work from a user’s perspective. 

These scenarios, typically written in the Gherkin syntax using the “Given–When–Then” structure, act as a common language between technical and non-technical team members. By doing so, BDD bridges the communication gap, ensures shared understanding, and keeps development efforts aligned with business goals. In essence, BDD supports TDD by guiding the creation of tests based on well-defined behaviors, making it easier to verify that the system delivers the expected outcomes.

When is BDD implemented?

During an initial conversation between the product owner and the customer, discuss what the application should do and the functionality of each feature. The product owner provides concrete examples to avoid assumptions and ensure clarity. 

When the product owner meets with developers and testers, they discuss these functionalities by analyzing the requirements presented by the client. Together, they write the main scenarios for each new functionality using a common language. This collaborative process ensures that the entire team is aligned and involved, helping to reduce ambiguity and disagreements about the feature. It guarantees that everyone has a unified vision of what the feature should achieve.

The scenarios developed during this phase serve as a guide for the developers during implementation, provide a high-level foundation for the tester's detailed test suite, and create a clear documentation base for test automation. This documentation is accessible to everyone on the team, including stakeholders, thanks to its easy-to-understand language. 

How are BDD scenarios written?

To write test scenarios that follow BDD principles, developers use Gherkin. Gherkin is a domain-specific language (DSL) used in BDD to write test scenarios in a simple, structured, and readable format. Its main goal is to bridge communication between technical and non-technical stakeholders—such as developers, testers, and business analysts—by describing system behavior using plain, human-readable language. The scenarios are defined from the user's perspective, avoiding technical language such as database operations or UI selectors. This encourages teams to think in terms of what the system does instead of how it does it. 

Gherkin scenarios act as a shared source of truth, ensuring everyone has a clear understanding of what the system should do before development begins. Each scenario represents a concrete example of a specific functionality, promoting collaboration, reducing ambiguity, and supporting automated test execution across different tools and frameworks.

To write test scenarios using Gherkin, you need to use the following keywords:

• Given: represents the user's initial state. It is the starting point for testing, ensuring that all prerequisites have already been executed.
• When: describes the action that the user needs to perform to validate the test case. This is the trigger that starts the change in the system's state.
• Then: is the expected result that must be validated within the test case. It can describe one or more outputs, and you can add "AND" to complement it.

Example of a BDD test scenario

To provide a more practical example, here is a scenario that demonstrates this functionality in action:

Feature: Manage email visibility (delete/archive)

As an email user,

I want to delete or archive an email,

So that I can effectively manage the visibility of my messages in the inbox.

Scenario 1: Deleting an email

Given I am viewing my inbox,
When I delete an email,
Then an alert confirmation pop-up should appear,
And the email should be moved to the Trash folder.

Scenario 2: Undo deletion

Given I have deleted an email,
When I select the "Undo" option from the alert pop-up,
Then the email should reappear in the inbox.

Outline scenario: Email management actions

Given I am viewing my inbox,
When I <Action> an email,
Then an alert confirmation pop-up should appear,
And the email should be moved to the <Expected Outcome> folder.

Notes

Using this outline scenario enables grouping of related actions (delete and archive) under a single reusable test case, providing flexibility in testing various outcomes based on the action taken. This structured approach supports consistent validation of email management features and ensures reusability across similar functionalities.

The benefits of implementing BDD

By incorporating BDD into Agile testing, teams can reap plenty of benefits. Here’s a list of some of the top ones:

1. Reduce ambiguity and miscommunication: BDD scenarios ensure all team members share a common understanding of requirements, which is fundamental to Agile’s collaborative nature.
2. Improve quality through clear examples: BDD encourages creating “Given-When-Then” scenarios that illustrate the desired outcomes. This aligns with Agile testing’s goal of catching issues early and continuously, making BDD a natural fit within Agile’s rapid testing cycles.
3. Reduces waste: The whole team is focused together on delivering what is needed and required from the business, so unneeded features are left over on the backlog, and BDD helps the team to focus on what is actually the highest priority. 
4. Easier and safer changes: As it is used as a common language, it's easy for the stakeholders to understand practically what is in the documentation, so any changes that are made are easier and safer to catch up with. 

The challenges of implementing BDD

BDD is not without its downsides. So before you jump to it, here are some key considerations and challenges to look out for:

1. High cross-team collaboration: The principles of BDD are to have collaboration between team members and faster feedback. If it's not possible to have regular meetings and feedback, the gains of BDD will not be so clear.
2. Works better in Agile: As Agile methodology promotes shorter cycles (sprints), BDD helps to ensure that the functionality is working as expected from the beginning till the end of the Sprint, and if it's not, it’s easier to catch any ambiguous or divergences due to the frequency of interactions the team has.
3. Scalability across large teams: When multiple people from the same team work on a product, it might be tougher to use a common vocabulary. To bypass this, it’s a good practice to use a shared glossary of terms and use them uniformly. 
4. Poor writing scenarios: Teams often write scenarios that are too technical, turning them into “test scripts” instead of business-readable behavior, or even the opposite - scenarios are too vague, losing system behaviours perspective, the focus must be on the feature intent and not only UI actions.

Final thoughts

BDD stands out as an effective approach to software development by aligning communication between everyone involved in the process, from developers and software testers to product owners and business stakeholders. Its ability to specify the expected behavior of the system through clear and shared examples favors the creation of features that truly meet the customer's needs. 

Furthermore, BDD promotes test automation in a collaborative and accessible way, ensuring a quick feedback cycle, essential for the continuous delivery of value in agile methodologies. BDD also reinforces the focus on business value, making it an ideal choice for teams adopting agile development.

Beyond improving communication and automation, BDD adds measurable value to the entire software development lifecycle by enhancing traceability between business requirements, test cases, and implemented functionality. This alignment allows teams to quickly identify the impact of changes, maintain test relevance over time, and ensure that every delivered feature contributes directly to business goals. However, adopting BDD also requires commitment from the entire team. Its success depends on consistent collaboration, well-defined communication, and discipline in maintaining clear and meaningful scenarios.