Behavior-Driven Development

After understanding how Test-Driven Development (TDD) emphasizes writing tests before code, we're ready to dive into Behavior-Driven Development (BDD), a methodology that expands on TDD by involving stakeholders more directly in the testing and development process.

Behavior-Driven Development is a software development methodology that prioritizes the behaviors and features that the user expects, transforming them into testable specifications. Rather than writing technical test cases first, BDD encourages us to capture these behaviors in a more natural, user-friendly language, often called "user stories" or "scenarios".

Key Concepts of BDD

Gherkin syntax is central to BDD, allowing teams to write scenarios in a structured, understandable way. The basic format is:

• Given: initial context or starting condition;
• When: the action or behavior performed;
• Then: the expected outcome or response.

For example, we can consider scenario of adding an item to the cart in e-commence platform:

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Scenario: Successfully add a product to the cart
  Given a customer is viewing a product on the website
  When the customer clicks on "Add to Cart"
  Then the item should be added to their shopping cart
  And the cart icon should display the correct item count

Here Given sets the initial condition that the customer is viewing a product. When specifies the action, i.e., clicking on "Add to Cart." Then defines the expected outcome, which includes both the addition of the product to the cart and the correct item count on the cart icon.

BDD vs TDD

Example

Let's try to model several processes in e-commence platform using BDD approach.

User Login

BDD scenarios for login cover various user interactions with the login functionality, verifying both success and error handling. Example scenarios include:

Successful Login

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Given the user is registered and provides correct login credentials,
When they click "Login,"
Then they should be redirected to their account dashboard.

Incorrect Password Warning

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Given the user enters their email and an incorrect password,
When they click "Login,"
Then a warning message should appear stating "Incorrect password."

Locked Account After Multiple Failed Attempts

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Given the user enters incorrect login credentials three times,
When they attempt to log in a fourth time,
Then the system should display a "Your account has been locked" message.

Product Search

BDD scenarios for search functionalities help users locate products effectively, catering to various search methods and ensuring a smooth browsing experience.

Search by Keyword

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Given a user types "headphones" in the search bar,
When they press "Search,"
Then a list of products related to "headphones" should display, sorted by relevance.

Filter by Category and Price Range

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Given the user is viewing "Electronics" products,
When they apply a price filter from $50 to $100,
Then only electronics within this price range should appear in the search results.

Checkout Process

The checkout process involves multiple steps, each of which can be tested to ensure users experience a smooth transaction.

Apply Discount Code

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Given the user is in the checkout process,
When they enter a valid discount code,
Then the total amount should update, reflecting the discount.

Shipping Option Selection

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Given the user has added items to their cart and proceeds to checkout,
When they select "Express Shipping,"
Then the shipping cost and estimated delivery date should adjust accordingly.

BDD scenarios for these core functionalities contribute to enhanced testing coverage and collaboration between business and development teams, ensuring features are designed to meet user expectations.