Test doubles

Test doubles are objects that stand in for other objects during a test. There are different types of test doubles with different purposes:

Stubs

• Mechanism for injecting data directly into the class .
• Usually created using a mocking framework.
• Does not provide validation of how the class uses the depandancy.
• Used when data is required by the class but the process used to obtain it isn't relevent to what's being tested.

Mocks

• Mechanism for validating how a dependency is used for the class.
• Created using a mocking framework.
• Can provide data and/or logic required by the class .
• Used when the test requires that the class performs specific actions on the dependency.

Fake

• Simplified implementation of a dependancy.
• Usually codded directly, without the use of a framework.
• Does not provide direct validation of how the class usses the depandency.
• Used when the class being tested requires specific logic in depeandency.