Setting up a Moq Mock<Interface> call to a method that returns a string

Question

I've got a class and a method that looks something like this:

public class FieldLookup : IFieldLookup
{
    public string LookupField(string Var1, string Var2)
    {
        // do a database lookup
    }
}

This works fine in the actual class where it's being used with Dependency Injection. What I'm trying to figure out is how, in the Unit Test, do I use the Moq framework to mock a call to this method.

var fieldLookup = new Mock<IFieldLookup>();

Then, how do I do this....?

fieldLookup.Setup<string>(x => x.LookupField("", "").Returns("something"));
fieldLookup.Setup(x => x.LookupField("", "").Returns("something"));

Both of these tell me that "String does not contain a definition for Return". Been playing around, but not getting it.

Answer 1

You put parentheses on the wrong place, you need to call the Returns method on the object returned by the Setup method.

fieldLookup.Setup<string>(x => x.LookupField("", "")).Returns("something");
fieldLookup.Setup(x => x.LookupField("", "")).Returns("something");