A Test Double is a replacement component used during testing to simulate the behaviour of real components. It allows testers to isolate specific parts of a system while performing tests.
Types of Test Doubles:
- Stubs: Provide predefined responses to calls made during tests.
- Mocks: Verify interactions between components by checking if specific calls were made.
- Fakes: Implement a simplified version of a component with limited functionality.
Test Doubles are Essential for:
- Testing components in isolation.
- Reducing dependencies on external systems during testing.
- Facilitating faster and more reliable tests.
Using Test Doubles enhances the flexibility and efficiency of the testing process, allowing for more thorough validation of individual components.