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Cucumber Cheat Sheet

A comprehensive guide to Cucumber, covering Gherkin syntax, step definitions, configuration, and best practices for writing effective and maintainable automated tests.

Gherkin Syntax Essentials

Feature and Scenario Structure

Feature: Describes a high-level feature of the application.

Scenario: A specific example of how the feature should behave.

Scenario Outline: A template for multiple scenarios with different data.

Examples: Table of data used with Scenario Outline.

Example:

Feature: User Authentication
  Scenario: Successful login
    Given User is on the login page
    When User enters valid credentials
    Then User should be logged in

Keywords

Given

Sets up the initial context of the scenario.

When

Describes an event or action performed by the user.

Then

Specifies the expected outcome or result.

And, But

Used to chain multiple Given, When, or Then steps for readability.

Background

A set of steps that run before each scenario in a feature.

Data Tables and Doc Strings

Data Tables: Used to pass structured data to a step definition.

Doc Strings: Used to pass larger blocks of text to a step definition.

Data Table Example:

Given the following users exist:
  | username | password |
  | john     | secret   |
  | jane     | password |

Doc String Example:

Given the following message:
  """
  This is a long message
  that spans multiple lines.
  """

Step Definitions

Basic Step Definition Structure

Step definitions link Gherkin steps to code that executes those steps.

Given('User is on the login page') do
  # Code to navigate to the login page
end

Step definitions typically use regular expressions to match the Gherkin step text.

Regular Expression Usage

.*

Matches any character (except newline) zero or more times.

(\d+)

Matches one or more digits and captures the value.

([^"]*)

Matches any character except a double quote, zero or more times, and captures the value.

^(.*)$

Matches the entire line and captures it.

Step Definition with Arguments 

Given('User enters {string} as username') do |username|
  # Code to enter the username
  fill_in('username', with: username)
end

Given('the product name is {word}') do |product_name|
  # ...
end

Configuration and Hooks

Cucumber Configuration

Cucumber is typically configured using a cucumber.yml file or command-line options.

Key configuration options include:

  • paths: Specifies the location of feature files.
  • requires: Specifies files to load before running tests (e.g., step definitions, support files).
  • profiles: Defines different configurations for different environments (e.g., test, development).

Example cucumber.yml:

default: --format pretty
test: --format progress --tags @test

Hooks

Before

Runs before each scenario or a tagged scenario.

After

Runs after each scenario or a tagged scenario.

Around

Wraps around each scenario, allowing you to perform actions before and after the scenario.

AfterStep

Runs after each step.

Hook Examples 

Before('@database') do
  # Code to set up the database
end

After do |scenario|
  # Code to take a screenshot if the scenario fails
  if scenario.failed?
    save_screenshot('screenshot.png')
  end
end

Advanced Cucumber Techniques

Tagged Hooks and Scenarios

Tags are used to organize and filter scenarios and hooks.

Scenarios can be tagged directly in the feature file:

@smoke
Scenario: Successful login
  ...

Hooks can be tagged to run only for specific scenarios:

Before('@smoke') do
  # Code to run before smoke tests
end

Parallel Execution

Cucumber can be configured to run scenarios in parallel, significantly reducing test execution time.

This often involves using a gem like cucumber-parallel or parallel_tests.

Configuration typically involves specifying the number of parallel processes to use.

Best Practices

  • Write clear and concise Gherkin features: Features should be easy to understand by both technical and non-technical stakeholders.
  • Keep step definitions focused: Step definitions should perform a single, well-defined action.
  • Avoid duplication: Use hooks and helper methods to avoid repeating code in step definitions.
  • Use data tables and doc strings effectively: These features can help make your scenarios more readable and maintainable.
  • Run tests frequently: Integrate Cucumber tests into your CI/CD pipeline to catch issues early.
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