Writing Scenarios and Scenario Outlines - Cucumber Tutorial

In Cucumber, scenarios are written in Gherkin language to define the behavior of an application in a human-readable format. Scenarios are the actual test cases, and Scenario Outlines are used for data-driven testing. In this tutorial, you will learn how to write scenarios and scenario outlines, along with examples and best practices for creating clear and reusable scenarios.

Writing Scenarios

A scenario consists of a series of steps that define the behavior of the application. Each step starts with one of the Gherkin keywords: Given, When, Then, And, or But. Here's an example of a simple scenario for a login feature:


    Feature: Login Functionality

    Scenario: Successful Login

    Given the user is on the login page

    When the user enters valid credentials

    Then the user should be logged in successfully

In the above scenario, the Given step defines the initial state, the When step represents the action, and the Then step defines the expected outcome.

Writing Scenario Outlines

Scenario Outlines are used when you want to test the same behavior with different sets of data. It allows you to create data-driven scenarios by using placeholders for the test data. Here's an example of a Scenario Outline:


    Feature: Adding Numbers

    Scenario Outline: Adding two numbers

    Given I have entered <number1> into the calculator

    And I have entered <number2> into the calculator

    When I press add

    Then the result should be <sum> on the screen

    Examples:

    | number1 | number2 | sum |

    | 2       | 3       | 5   |

    | 10      | 5       | 15  |

In the above Scenario Outline, placeholders <number1>, <number2>, and <sum> are used to represent different sets of data for testing the addition operation. The Examples section provides the test data for each set of input values.

Best Practices for Writing Scenarios and Scenario Outlines

Follow these best practices to create effective scenarios and scenario outlines:

Keep Scenarios Atomic: Each scenario should test a specific behavior or functionality independently.
Use Meaningful Scenario Names: Choose descriptive names that convey the purpose of the scenario.
Avoid Technical Details: Focus on the desired behavior rather than technical implementation details.
Use Scenario Outlines for Data-Driven Testing: Utilize Scenario Outlines when testing the same behavior with different data inputs.
Use Examples Wisely: Provide concise and relevant test data in the Examples section of the Scenario Outline.
Use Step Definitions: Implement step definitions to reuse common steps across scenarios and improve maintainability.

Common Mistakes with Scenarios and Scenario Outlines

Creating overly long scenarios with multiple unrelated steps.
Not providing clear and concise Examples for the Scenario Outline.
Using hard-coded data in scenarios instead of placeholders for data-driven testing.
Not following the Given-When-Then structure, leading to unclear scenarios.
Writing scenarios that test too many behaviors at once, making it difficult to identify the cause of failures.

Frequently Asked Questions (FAQs)

Q: Can I use multiple "Given," "When," or "Then" steps in a scenario?
A: Yes, you can use multiple "Given," "When," or "Then" steps to describe the behavior of the application in more detail.
Q: Can I use Examples in a regular scenario?
A: No, Examples are specific to Scenario Outlines and are used for data-driven testing.
Q: Can I use the same Examples table for multiple Scenario Outlines?
A: Yes, you can reuse the Examples table in multiple Scenario Outlines, but ensure the placeholders match the table columns.
Q: How can I avoid duplication in step definitions?
A: Use parameterized step definitions and pass data dynamically to avoid duplication.
Q: Should I write different scenarios for positive and negative test cases?
A: Yes, it's a good practice to write separate scenarios for positive and negative test cases to keep them focused and clear.

Summary

Writing scenarios and scenario outlines in Gherkin is an essential part of Behavior-Driven Development using Cucumber. By following best practices, keeping scenarios atomic, and using scenario outlines for data-driven testing, you can create effective and reusable scenarios that help ensure the quality of your software applications.