Understanding Gherkin Syntax

Gherkin is a domain-specific language used in Behaviour-Driven Development (BDD) to define test cases in a natural, readable format. Its purpose is to describe the behaviour of the software in a way that is understandable by all stakeholders, including developers, testers, and business analysts. Gherkin serves as a bridge between technical and non-technical team members, fostering better communication and collaboration.

Key Features of Gherkin Syntax

Gherkin syntax is structured and simple, making it easy to write and understand. Here are some of the key features:

1. Feature Files

Gherkin scenarios are written in feature files, which describe the high-level functionality of the system. A feature file typically begins with the keyword Feature, followed by a brief description of the feature.

Example:

Feature: User login
  As a user
  I want to log in to the application
  So that I can access my account

2. Scenarios

Each feature can have multiple scenarios that describe specific examples of the feature's behaviour. Scenarios are defined using the keyword Scenario, followed by a description.

Scenario: Successful login
  Given the user is on the login page
  When the user enters valid credentials
  Then the user should be redirected to the dashboard

3. Steps

Scenarios are composed of steps that define the actions and expected outcomes. Steps use the keywords Given, When, Then, And, and But to describe the context, actions, and results.

4. Given-When-Then Structure

• Given: The Given step describes the initial context or state of the system before an action is taken. It sets up the preconditions for the scenario.

• When: The When step specifies the action or event that occurs. It describes the trigger that causes the behaviour to be tested.

• Then: The Then step defines the expected outcome or result of the action. It verifies that the system behaves as expected.

• The And and But keywords are used to add additional conditions to Given, When, or Then steps. They help to create more complex scenarios by chaining multiple conditions together.

Scenario: Successful login with welcome message
  Given the user is on the login page
  When the user enters valid credentials
  Then the user should be redirected to the dashboard
  And the user should see a welcome message

5. Data Tables

Gherkin also supports data tables for scenarios that require multiple sets of inputs and expected outcomes. Data tables provide a structured way to present this information.

The Scenario Outline keyword is used to run the same scenario multiple times with different sets of data. This is useful for testing various input combinations. The Examples keyword is used to define the data sets.

Scenario Outline: Login attempts
  Given the user is on the login page
  When the user enters <username> and <password>
  Then the user should see <message>

  Examples:
    | username | password | message           |
    | user1    | pass1    | Welcome, user1!   |
    | user2    | pass2    | Welcome, user2!   |

6. Background

The Background keyword is used to define a common set of steps that apply to all scenarios in a feature. This helps to avoid repetition and keep the scenarios concise.

Feature: User login

  Background:
    Given the user is on the login page

  Scenario: Successful login
    When the user enters valid credentials
    Then the user should be redirected to the dashboard

  Scenario: Unsuccessful login
    When the user enters invalid credentials
    Then the user should see an error message

Gherkin syntax is a crucial component of BDD, enabling teams to write clear and concise scenarios that describe the behaviour of the system. By using a structured and natural language format, Gherkin helps to ensure that everyone on the team has a shared understanding of the requirements and expected behaviour. This collaborative approach leads to better communication, fewer misunderstandings, and higher-quality software.