It looks like nSubsitute is just testing itself rather than my code

Question

Possibly stupid question. In the docs they give this example

calculator.Add(1, 2).Returns(3);
Assert.That(calculator.Add(1, 2), Is.EqualTo(3));

Am I testing that the actual calculator returns 3 or just that the substitute does? If the latter, what is the point?

Answer 1

I'm not sure where my brain went, but I seem to have momentarily lost the point of a mock. Saying

calculator.Add(1, 2).Returns(3)

is the wrong example. A much better example would be

var person = database.GetMember(123) returns "Jesse Liberty"

not so that I can test the mock, but so that I can test code that depends on the database.

Obvious, I know, but sometimes the brain just shuts down.