Workflow Foundation - Literal only supports value types and the immutable type System.String

Question

I have the following unit test for a WF code activity called MyCodeActivity:

[ExpectedException(typeof(ArgumentException))]
[TestMethod]
public void ShouldRequireParam()
{
    //arrange
    var invoker = new WorkflowInvoker(new MyCodeActivity()
    {
        MyInt = 2,
        MyComplexObject = _complexObject
    });

    //act
    invoker.Invoke();

    //assert
    Assert.Fail("Expected ArgumentException");
}

When I run the test I get the following exception

'Literal< MyComplexObject>': Literal only supports value types and the immutable type System.String. The type MyComplexObject cannot be used as a literal.

Answer 1

To fix the immediate problem:

MyComplexObject = _complexObject

to

MyComplexObject = new InArgument<MyComplexObject>((ctx) => _complexObject)

Further reading : http://msdn.microsoft.com/en-us/library/ee358749.aspx .

Note: You should also use the Microsoft.Activities.UnitTesting package available on NuGet. It makes IOC alot easier (seeing as WF works with the Service Locator pattern and not Dependency Injection)