How can I assert that a particular method was called using NUnit?

Question

How can I test that a particular method was called with the right parameters as a result of a test? I am using NUnit.

The method doesn't return anything. it just writes on a file. I am using a mock object for System.IO.File. So I want to test that the function was called or not.

Answer 1

More context is needed. So I'll put one here adding Moq to the mix:

pubilc class Calc {
    public int DoubleIt(string a) {
        return ToInt(a)*2;
    }

    public virtual int ToInt(string s) {
        return int.Parse(s);
    }
}

// The test:
var mock = new Mock<Calc>();
string parameterPassed = null;
mock.Setup(c => x.ToInt(It.Is.Any<int>())).Returns(3).Callback(s => parameterPassed = s);

mock.Object.DoubleIt("3");
Assert.AreEqual("3", parameterPassed);