Unit Testing with MoQ Framework in .NET

1. TESTING AND MOCKING
WITH THE MOQ FRAMEWORK
BY: ARTHUR CHARLTON
EMAIL: LYNXSTAR@KERVANA.COM

2. UNIT TESTS VS “UNIT TESTS”
• Different test types
• Unit Test – Atomic, method sized, used for TDD, isolated
• Functional/Feature Test – Story/task requirements, isolated
• Acceptance Test – Black box test of a piece of functionality by itself
• Integration Test – Black box testing of the system as a whole, test
harness

3. AAA PATTERN
• Arrange – Configure testing infrastructure (mocking, DI, etc)
• Act – Execute the method under test
• Assert – Verify results

4. CODE DEPENDENCIES
• Dependency Inversion Principle is your friend
• Spaghetti Code is hard to test
• Heavily coupled code is hard to isolate for unit and functional
testing
• Coupled code can lead to large unit tests.
• Depend on abstractions not concretions

5. TESTING PRIORITIES
• Output
• Service Dependencies
• State

6. MOCKING
• Assists in isolating the method/class/component under test.
• Allows you to simulate parts of the system during test
• Isolation helps with unit test and functional test level problems

7. MOQ
• .NET Mocking Framework
• Handles mocking boilerplate
• Gives you powerful assertion tools
• Can mock both abstraction and virtual concretions

8. CREATING A MOQ

9. VERIFY
• Used to assert that a moq method has been called under
certain conditions
• Allows you verify the amount of calls
• Allows you to verify the parameters passed in

10. VERIFY - TIMES
• The Times struct lets you specific invocation amount
restrictions when verifying.
• Exactly
• At Most
• At Least
• Between
• Once/Never as convenience

11. VERIFIABLE - EXAMPLE

12. SETUP - RETURNS
• Allows you to configure what a mocked out method will return
• Chain .Returns(delegate) onto a setup method.
• Return delegate
• Type of Func<ParameterType1, ParameterType2,… ReturnType>
• Input: All method arguments
• Output: Method output
• Great place to use lambda expressions

13. RETURNS - EXAMPLE

14. CONTINUED

15. RETURN PITFALLS
• Be careful of shortcuts.
• Returns(SomeCollection.Count) will only be evaluated once,
regardless of how many times the mocked method is invoked
• Returns(() => SomeCollection.Count) will be evaluated every
time.
• This applies to just returning a variable too, if for some reason
this would change in between invocations you need to use a
delegate.

16. CALLBACKS
• Arbitrary block of code to be executed every time a mocked out
method is invoked.
• Useful for functional testing when trying to simulate parts of
the system.
• Similar to returns it takes in a delegate
• Action, matching the parameter type/order
• No returns
• You can chain a callback to a return

17. CALLBACKS

18. THE POWER OF IT
• It is a special class that is a part of MoQ
• Allows you to configure mocked method arguments in a
generic manner

19. IT - SETUP

20. IT- VERIFY

21. IT – VARIATIONS
• It.Is
• Func<Ptype, bool> - Pass it a delegate that determines if it is a match
• It.IsAny<Ptype> (Most commonly used)
• Passes if parameter is the supplied type
• It.IsIn
• Passes if parameter is in the supplied collection
• It.Regex
• Passes if string parameter passes the regex, fails if not string parameter

22. QUESTIONS/DEMO
• Any questions?
• Time to show off some real code running with MoQ