Isolation

Guide on Isolation in TDD for PMI-ACP

Isolation is a principle concept in Test Driven Development (TDD).
What is it?
Isolation in TDD refers to the ability to test individual units or components of a program without requiring any dependencies. This is essential as it allows for more reliable, quicker and easier testing.
Why is it important?
Isolation helps in identifying issues or defects in specific components without interference from dependencies. It enhances independent testing, which contributes to the overall code quality, maintainability and understanding of the system.
How does it work?
In isolation, tests are written for each individual component or unit. These tests are run independently of other components, thus isolating them. If these tests pass, it ensures that the unit under test is functioning as expected and without impact from dependencies.
Exam Tips: Answering Questions on Isolation
1. Understand the concept and importance of Isolation.
2. Familiarise with its application in TDD.
3. Practice questions related to this topic.
4. It's vital to know that in Isolation, tests should only fail for one reason, which is when the component under test does not meet the required functionality.
5. Isolation is typically achieved using techniques like stubs, mocks, and fakes which replicate the behavior of dependencies, allowing the unit to be tested in isolation.