PosInformatique.Moq.Analyzers

PosInfoMoq1005: Defines the generic argument of the SetupSet() method with the type of the mocked property.

Property	Value
Rule ID	PosInfoMoq1005
Title	Defines the generic argument of the SetupSet() method with the type of the mocked property.
Category	Design
Default severity	Warning

Cause

A property setter has been set up using SetupSet() without a generic argument that represents the type of the mocked property.

Rule description

Moq provides two methods to mock a property setter:

• Mock<T>.SetupSet(Action<T>)
• Mock<T>.SetupSet<TProperty>(Action<T, TProperty>)

When setting up a property setter, use Mock<T>.SetupSet<TProperty>(Action<T, TProperty>) by explicitly defining the type of the property to mock. This overload of the SetupSet() method allows you to define a typed Callback() and avoid exceptions if the delegate argument in the Callback() does not match the property type.

For example, consider the following code to test:

[Fact]
public interface Customer
{
	string Name { get; set; }
}

If you mock the setter of the Customer.Name property, you should set up the property with the SetupSet<string>() method:

[Fact]
public void SetNameOfCustomer()
{
	var customer = new Mock<Customer>();
	customer.SetupSet<string>(c => c.Name = "Gilles")   // The SetupSet<string>() version is used.
		.Callback((string value) =>
		{
			// Called when the setter of the property is set.
		});
}

The following code violates the rule because the SetupSet() method has no generic argument:

[Fact]
public void SetNameOfCustomer()
{
	var customer = new Mock<Customer>();
	customer.SetupSet(c => c.Name = "Gilles")		// The SetupSet() has been used without set the generic argument.
		.Callback((string value) =>
		{
			// Called when the setter of the property is set.
		});
}

If the non-generic version of the SetupSet() method is used, the delegate in the Callback() method cannot be checked at compile time, an exception will occur during the execution of the unit test:

[Fact]
public void SetNameOfCustomer()
{
	var customer = new Mock<Customer>();
	customer.SetupSet(c => c.Name = "Gilles")
		.Callback((int value) =>		// The code compiles, but during the execution of the unit test
		{                               // an ArgumentException will be thrown.
		});
}

How to fix violations

To fix a violation of this rule, use the SetupSet<TProperty>() method with the type of the mocked property as the generic argument.

Visual Studio fixer

A Visual Studio fixer exists to set explicitly the generic argument of the SetupSet<T>() method with the property type in the current document, project or solution.

When to suppress warnings

Do not suppress a warning from this rule. Using the SetupSet<T>() method ensures that the delegate argument in the Callback() method matches the type of the property.

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