PosInfoMoq2003.md

PosInfoMoq2003: The Callback() delegate expression must match the signature of the mocked method

Property	Value
Rule ID	PosInfoMoq2003
Title	The Callback() delegate expression must match the signature of the mocked method
Category	Compilation
Default severity	Error

Cause

The delegate in the argument of the Callback() method must match the signature of the mocked method.

Rule description

The lambda expression in the argument of the Callback() method must match the signature of the mocked method.

For example, the Callback() have a lambda expression with the (string, double) signature which does not match the GetData() mocked method which have the (string, int) signature.

[Fact]
public void Test()
{
    var service = new Mock<Service>();
    service.Setup(s => s.GetData("TOURREAU", 1234))
        .Callback((string n, double age) =>		// Different signature of the GetData() method.
        {
        	// ...
        })
        .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 to use the mocked method signature in the Callback() method.

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 MoqException thrown with the "Invalid callback. Setup on method with parameters (xxx) cannot invoke callback with parameters (yyy)." message.