gherkin-authoring

# Gherkin Authoring

Gherkin/BDD acceptance criteria authoring for executable specifications.

## When to Use This Skill

**Keywords:** Gherkin, Given/When/Then, BDD, behavior-driven development, feature files, scenarios, acceptance criteria, Reqnroll, Cucumber, SpecFlow, executable specifications

**Use this skill when:**

- Writing acceptance criteria in Given/When/Then format
- Creating .feature files for BDD testing
- Converting requirements to executable specifications
- Setting up Reqnroll tests in .NET projects
- Understanding Gherkin syntax and best practices

## Quick Syntax Reference

### Feature File Structure

```gherkin
Feature: <Feature Name>
  <Feature description>

  Background:
    Given <common precondition>

  Scenario: <Scenario Name>
    Given <precondition>
    When <action>
    Then <expected outcome>

  Scenario Outline: <Parameterized Scenario>
    Given <precondition with <parameter>>
    When <action with <parameter>>
    Then <expected outcome with <parameter>>

    Examples:
      | parameter |
      | value1    |
      | value2    |
```

### Step Keywords

| Keyword | Purpose | Example |
| --- | --- | --- |
| `Given` | Setup preconditions | Given a user is logged in |
| `When` | Describe action | When the user clicks submit |
| `Then` | Assert outcome | Then the form is saved |
| `And` | Additional step (same type) | And an email is sent |
| `But` | Negative condition | But no error is shown |

## Writing Effective Scenarios

### The Three A's Pattern

Gherkin maps to the Arrange-Act-Assert pattern:

| Gherkin | AAA | Purpose |
| --- | --- | --- |
| Given | Arrange | Set up the test context |
| When | Act | Perform the action under test |
| Then | Assert | Verify the expected outcome |

### Single Behavior Per Scenario

**Good - One behavior:**

```gherkin
Scenario: User login with valid credentials
  Given a registered user exists
  When the user enters valid credentials
  Then the user is logged in
```

**Bad - Multiple behaviors:**