Behavior Driven Development

Behavior Driven Development, or BDD, bridges the gap between business requirements and automated tests. Requirements are written in a shared, natural language that developers, testers, and stakeholders all understand. BDD eliminates misunderstandings and creates a unified view of the desired behavior.

In a Nutshell

• BDD describes behavior in natural language using the Given-When-Then structure.
• It fosters collaboration between business, development, and quality assurance.
• Tools like Cucumber, SpecFlow, or Behave translate scenarios into executable tests.
• BDD is not a testing method—it’s a communication and development practice.

Compact Definition

BDD evolved from TDD and focuses on software behavior from a business perspective. Instead of describing technically which method produces which result, examples are written in the language of users. These examples become tests that serve simultaneously as specifications and living documentation.

The Given-When-Then Schema

Given

Describes the initial state or preconditions for a scenario.

When

Describes the action being performed.

Then

Describes the expected result or response.

Example Scenario

Scenario: Customer receives discount on large purchase

Given a customer has items worth 200 euros in their cart
When the customer proceeds to checkout
Then the total should be reduced by 20 euros

Essential Tools

• Cucumber: Popular BDD framework for Java, Ruby, JavaScript, and many other languages.
• SpecFlow: BDD framework for .NET.
• Behave: BDD framework for Python.
• Serenity BDD: Cucumber extension with enhanced reporting capabilities.
• Gauge: Lightweight BDD alternative from ThoughtWorks.

Practical Example: Cucumber Feature for an Order Process

Feature: Discount calculation

  Scenario: Standard discount from 100 euros
    Given the cart contains items worth 100 euros
    When the customer starts the checkout process
    Then a discount of 10 euros is applied
    And the new total is 90 euros

  Scenario: No discount below 100 euros
    Given the cart contains items worth 50 euros
    When the customer starts the checkout process
    Then no discount is applied
    And the total remains 50 euros

Advantages and Disadvantages

Advantages

• Shared Language: Business and development discuss the same examples.
• Clear Requirements: Misunderstandings surface before implementation begins.
• Living Documentation: Scenarios clearly describe system behavior.
• Focus on Business Value: Tests align with business outcomes, not technical implementation.

Disadvantages

• Effort: Creating and maintaining scenarios requires time.
• Complexity: Large feature files can become hard to manage.
• Stakeholder Dependency: Without regular involvement from the business side, impact diminishes.
• Technical Maintenance: Poorly maintained step definitions cause maintenance headaches.

Exam-Relevant Key Points

• Definition and purpose of BDD.
• The Given-When-Then schema.
• Difference between BDD and TDD.
• Role of business, development, and QA.
• Common tools: Cucumber, SpecFlow, Behave.

Typical Exam Questions (with Brief Answers)

1. What is BDD? A practice that describes business behavior in natural language and uses it as tests.

2. What does Given-When-Then mean? It describes the precondition, action, and expected outcome of a scenario.

3. Name a BDD tool. Cucumber, SpecFlow, or Behave.

4. What is the main difference between BDD and TDD? BDD describes behavior from a business perspective, while TDD focuses on technical units.

5. What is an advantage of BDD? Business and development share a common understanding of requirements.

Key Sources

1. https://cucumber.io/docs/bdd/
2. https://specflow.org/bdd/
3. https://en.wikipedia.org/wiki/Behavior-driven_development

Continue on the Software Testing Learning Path

The next article in the Software Testing learning path covers Test Automation and Software Quality — how test automation improves software quality.