cucumber-gherkin

Cucumber & Gherkin

BDD testing framework with plain-text executable specifications and Ruby step definitions.

Feature file (.feature) ──> Step Definitions (Ruby) ──> System under test

Gherkin Quick Reference

Feature: Short description
  Optional multi-line description.

  Background:
    Given common setup for all scenarios

  Rule: Business rule grouping (Gherkin 6+)

Scenario: Concrete example
  Given an initial context
  When an action occurs
  Then expected outcome
  And additional assertion
  But negative assertion

Scenario Outline: Parameterized
  Given there are <start> items
  When I remove <remove> items
  Then I should have <remaining> items

  Examples:
    | start | remove | remaining |
    |    12 |      5 |         7 |
    |    20 |      5 |        15 |

**Step keywords:** `Given` (setup), `When` (action), `Then` (assertion), `And`/`But` (continuation), `*` (bullet)

**Data tables:**
```gherkin
Given the following users exist:
  | name  | email             | role  |
  | Alice | alice@example.com | admin |

Doc strings:

Given a blog post with content:
  """markdown
  # My Post Title
  Content here.
  """

Tags: @smoke @critical on Feature/Rule/Scenario/Examples. Expressions: @smoke and not @slow, (@smoke or @critical) and not @wip

Ruby Step Definitions

# Cucumber Expressions (preferred)
Given('I have {int} cucumbers in my belly') do |count|
  @belly = Belly.new
  @belly.eat(count)
end

When('I wait {int} hour(s)') do |hours|
  @belly.wait(hours)
end

Then('my belly should growl') do
  expect(@belly.growling?).to be true
end

# Data table
Given('the following users exist:') do |table|
  table.hashes.each { |row| User.create!(row) }
end

# Doc string
Given('a JSON payload:') do |json|
  @payload = JSON.parse(json)
end

Cucumber Expressions: {int}, {float}, {word}, {string}, {} (anonymous). Optional: cucumber(s). Alternatives: color/colour.

State sharing: Use instance variables (@user) or World modules:

module MyWorld
  def current_user
    @current_user ||= create(:user)
  end
end
World(MyWorld)

Hooks

Before do |scenario|
  @browser = Browser.new
end

After do |scenario|
  save_screenshot("failure.png") if scenario.failed?
end

Before('@database') do
  DatabaseCleaner.start
end

After('@database') do
  DatabaseCleaner.clean
end

BeforeAll do
  # once before any scenario
end

AfterAll do
  # once after all scenarios
end

Order: BeforeAll > (Before > Background > Steps > After) per scenario > AfterAll

Running

bundle exec cucumber
cucumber --tags "@smoke and not @wip"
cucumber features/login.feature:10
cucumber --dry-run
cucumber --format html --out report.html
bundle exec parallel_cucumber features/

Best Practices

Declarative over imperative:

# Good                          # Avoid
When "Bob" logs in              When I visit "/login"
Then he sees his dashboard      And I enter "bob" in "username"
                                And I click "Login"

• Describe what the system does, not how
• One behavior per scenario, 3-5 steps
• Keep Background short (≤4 lines), essential context only
• Use domain language stakeholders understand

References

For comprehensive details:

• references/gherkin-syntax.md — Complete Gherkin language reference (keywords, data tables, tags, i18n)
• references/step-definitions.md — Ruby step definition patterns (data tables, doc strings, custom parameter types, World context, organization)
• references/hooks-config.md — Hooks, cucumber.yml configuration, reporters, Capybara integration
• references/best-practices.md — Anti-patterns, naming conventions, collaboration patterns, refactoring