Unit testing a method with Moq

c#, moq, unit-testing

Solution

Yes, you approaching it wrong, but don't worry, I'll explain why. First hint would be

you can completely remove your `User` class and everything will be the same.

When you are doing:

var userMock = new Mock<IUser>();

You just creating a fake\mock object of that interface, that has nothing to do with your initial `User` class, so it doesn't have any implementation of `CalculateAge` method, except of fake one that just silly returns 0. That's why you are getting 0 in your assert statement.

So, you were saying:

thought I could use mocking to give values to not-yet-developed method/properties in my objects, so the testing of a method wouldn't depend on another component of my class

You could, let's say you will have some consumer of your IUser, lets say like the following:

class ConsumerOfIUser
{
   public int Consume(IUser user)
   {
      return user.CalculateAge() + 10;
   }
}

in that case mocking of IUser will make total sense, since you want to test how your `ConsumerOfIUser` behaves when IUser.CalculateAge() returns 10. You would do the following:

var userMock = new Mock<IUser>();
userMock.Setup(u => u.CalculateAge()).Returns(10);

var consumer = new ConsumerOfIUser();
var result = consumer.Consume(userMock);

Assert.AreEqual(result, 20); //should be true

Problem

I'm trying to learn how to do Unit testing with C# and Moq, and I've built a little test situation. Given this code: ``` public interface IUser { int CalculateAge(); DateTime DateOfBirth { get; set; } string Name { get; set; } } public class User : IUser { public DateTime DateOfBirth { get; set; } string Name { get; set; } public int CalculateAge() { return DateTime.Now.Year - DateOfBirth.Year; } } ``` I want to test the method `CalculateAge()`. To do this, I thought I should try giving a default value to the `DateOfBirth` property by doing this in my test method: ``` var userMock = new Mock<IUser>(); userMock.SetupProperty(u => u.DateOfBirth, new DateTime(1990, 3, 25)); //Is this supposed to give a default value for the property DateOfBirth ? Assert.AreEqual(22, userMock.Object.CalculateAge()); ``` But when It comes to the assertion, the value of `CalculateAge()` equals 0, although `DateOfBirth` equals `new DateTime(1990, 3, 25)`. I know this may look like a silly example, but whatever... I thought I could use mocking to give values to not-yet-developed method/properties in my objects, so the testing of a method wouldn't depend on another component of my class, or even setting up a default context for my object (hence the name of the user here...) Am I approaching this problem the wrong way? Thanks.

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