PosInfoMoq2016.md

PosInfoMoq2016: Mock<T> constructor with factory lambda expression can be used only with classes.

Property	Value
Rule ID	PosInfoMoq2016
Title	Mock<T> constructor with factory lambda expression can be used only with classes.
Category	Compilation
Default severity	Error

Cause

The factory lambda expression used in Mock<T> instantiation must used only for the classes.

Rule description

When using a lambda expression in the constructor of Mock to create a mock instance, the mocked type must be a class.

[Fact]
public void Test()
{
    var service1 = new Mock<IService>(() => new Service());    // The factory lambda expression can be used only on classes type.
    var service2 = new Mock<Service>(() => new Service());     // OK
}

public interface IService
{
}

public class Service : IService:
{
    public Service(string a)
    {
    }
}

How to fix violations

To fix a violation of this rule, ensure that the lambda expression factory is used with a mocked type that is a class.

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 "Constructor arguments cannot be passed for interface mocks." message.