Crystal Mocking

Introduction to Crystal Mocking

Mocking in Crystal is an essential technique used in unit testing to isolate the code under test. By using mocks, you can simulate the behavior of complex objects and control their interactions, ensuring your tests are both independent and reliable. In Crystal, spec mocks are particularly useful for this purpose, offering a simple yet powerful way to create mock objects.

Why Use Mocks?

Mocks are used to:

• Isolate Tests: Ensure that the tests only verify the behavior of the code under test and not its dependencies.
• Control Behavior: Simulate different scenarios by controlling object behavior.
• Validate Interactions: Ensure that objects interact in the expected way.

Creating a Mock in Crystal

To create a mock in Crystal, you typically use the mock method provided by the Spec module. This method allows you to define the behavior of the mock object and its expectations.

Controlling Mock Behavior

One of the key advantages of using mocks is the ability to easily control their behavior. You can define what a mock should return when a method is called, or set expectations for how many times a method should be invoked.

Benefits of Using Crystal Mocks

Using mocks in your tests provides several advantages:

• Improved Test Speed: Tests run faster since they don't rely on actual implementations.
• Increased Test Accuracy: By isolating the code, you reduce the risk of false positives/negatives.
• Better Code Design: Mocks encourage better design patterns by highlighting dependencies and interactions.