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Cucumber Architecture Overview

Understanding Cucumber architecture is critical before writing feature files or step definitions. This section explains how different Cucumber components work together during execution.

High-Level Architecture​

Cucumber follows a layered architecture:

Feature Files (Gherkin)
        ↓
Step Definitions
        ↓
Automation Code (Selenium / API / DB)
        ↓
Execution Engine
        ↓
Reports

Each layer has a clear responsibility.

Core Components of Cucumber​

1️⃣ Feature Files​

  • Written in Gherkin language
  • Describe application behavior
  • Stored as .feature files
  • Business-readable

Example:

Feature: Login functionality

Feature files contain no automation code.

2️⃣ Step Definitions​

  • Written in Java (or other supported languages)
  • Map Gherkin steps to executable code
  • Act as a bridge between feature files and automation logic

Rule:

One step definition = one behavior implementation.

3️⃣ Automation Layer​

This is where actual testing happens:

  • Selenium WebDriver (UI)
  • API clients (REST Assured)
  • Database utilities

Cucumber does not automate anything by itself.

4️⃣ Runner Class​

  • Controls execution
  • Defines feature file location
  • Defines glue (step definition packages)
  • Enables tags, plugins, dry run

Runner connects Cucumber to the test framework (TestNG / JUnit).

5️⃣ Hooks​

  • Execute before/after scenarios
  • Manage setup and teardown
  • Capture screenshots on failure
  • Control driver lifecycle

Hooks are scenario-level controls.

6️⃣ Plugins & Reporting​

  • Generate HTML, JSON, XML reports
  • Integrate with Extent reports
  • Used for CI/CD reporting

Execution Flow (Step-by-Step)​

Runner starts execution
   ↓
Feature files are parsed
   ↓
Scenarios are identified
   ↓
Matching step definitions are found
   ↓
Automation code executes
   ↓
Hooks are triggered
   ↓
Reports are generated

Understanding this flow helps in debugging failures.

Cucumber + Test Framework Integration​

Cucumber itself:

  • Does not manage assertions
  • Does not manage parallel execution
  • Does not manage test lifecycle fully

Test frameworks like:

  • TestNG
  • JUnit

handle execution control.

Common Architecture Mistakes ❌​

  • Putting logic in feature files
  • Writing automation code in step definitions directly
  • Mixing hooks and test logic
  • Poor package organization

Interview-Ready Questions​

Q: What are the main components of Cucumber?
A: Feature files, step definitions, runner, hooks, automation layer.

Q: Does Cucumber execute Selenium code directly?
A: No, Selenium code runs inside step definitions.

Key Takeaways​

  • Cucumber has layered architecture
  • Feature files describe behavior
  • Step definitions connect behavior to code
  • Runner controls execution
  • Hooks manage setup and teardown
  • Automation tools do the real work