It.IsAny<T>() or It.Is<T>() arguments must match the parameters of the mocked method.| Property | Value |
|---|---|
| Rule ID | PosInfoMoq1006 |
| Title | The It.IsAny<T>() or It.Is<T>() arguments must match the parameters of the mocked method. |
| Category | Design |
| Default severity | Warning |
When setting up a method using It.IsAny<T>() or It.Is<T>() as arguments,
the type T must exactly match the parameters of the configured method.
Although the compiler checks the validity between the parameters and arguments of the configured method,
the type specified in It.IsAny<T>() or It.Is<T>() must still match the method parameters.
This is especially important when using nullable struct parameters, which can easily cause confusion.
For example, consider the following test code:
[Fact]
public interface IRepository
{
void DeleteUser(int? id)
}
If you mock the method from the IRepository type and use It.IsAny<int>() as the argument,
the following code will throw an exception because It.IsAny<int>() is treated as the integer value 0:
[Fact]
public void DeleteUser()
{
var repository = new Mock<IRepository>(MockBehavior.Strict);
repository.Setup(It.IsAny<int>());
repository.Object.DeleteUser(null); // Will raise an exception, because It.IsAny<int>() ('0') is different of `null`.
}
Instead, you should use It.IsAny<int?>() with a nullable int?,
which makes the method configuration explicit and avoids mismatches:
[Fact]
public void DeleteUser()
{
var repository = new Mock<IRepository>(MockBehavior.Strict);
repository.Setup(It.IsAny<int?>());
repository.Object.DeleteUser(null);
}
To fix a violation of this rule, ensure the type arguments used with It.IsAny<T>() or It.Is<T>() exactly match the parameters of the configured method.
You may suppress warnings from this rule, but for better readability and maintainability,
it is strongly recommended to always use matching type arguments in It.IsAny<T>() or It.Is<T>().