PosInfoMoq2014.md

PosInfoMoq2014: The Callback() delegate expression must not return a value.

Property	Value
Rule ID	PosInfoMoq2014
Title	The Callback() delegate expression must not return a value.
Category	Compilation
Default severity	Error

Cause

The delegate in the argument of the Callback() method must not return a value.

Rule description

The lambda expression in the argument of the Callback() method must not return a value.

[Fact]
public void Test()
{
    var service = new Mock<Service>();
    service.Setup(s => s.GetData("TOURREAU", 1234))
        .Callback((string n, int age) =>
        {
        	// ...
            return 1234;        // The delegate in the Callback() method must not return a value.
        })
        .Returns(10);
}

public interface IService
{
	public int GetData(string name, int age) { }
}

How to fix violations

To fix a violation of this rule, be sure that the delegate method in the Callback() method does not return a value.

When to suppress warnings

Do not suppress an error from this rule. If bypassed, the execution of the unit test will be failed with a ArgumentException thrown with the "Invalid callback. This overload of the "Callback" method only accepts "void" (C#) or "Sub" (VB.NET) delegates with parameter types matching those of the set up method. (Parameter 'callback')" message.