Mocking is a critical technique in unit testing, allowing developers to isolate code behavior by simulating dependencies. Here’s a concise guide:

🧩 What is Mocking?

  • Purpose: Replace real components (e.g., APIs, databases) with fake ones to control inputs/outputs
  • Key Benefits:
    • Ensures tests are repeatable and predictable
    • Reduces external dependencies
    • Accelerates test execution

🛠️ Popular Mocking Tools

  1. Mockito (Java)
    Mockito
  2. Sinon.js (JavaScript)
    Sinon_JS
  3. unittest.mock (Python)
    unittest_mock

📚 When to Use Mocking?

  • Testing network requests without real API calls
  • Isolating business logic from external systems
  • Verifying edge cases (e.g., errors, timeouts)

For deeper insights, explore our Testing Principles Tutorial.

💡 Tip: Always mock external services to maintain test stability!