Configuring C# out parameters with Foq in F# - unit-testing

Question

I am using F# and Foq to write unit tests for a C# project.
I am trying to set up a mock of an interface whose method has an out parameter, and I have no idea how to even start. It probably has to do with code quotations, but that's where my understanding ends.
The interface is this:
public interface IGetTypeNameString
{
bool For(Type type, out string typeName);
}
In C# Foq usage for the interface looks like this:
[Fact]
public void Foq_Out()
{
// Arrange
var name = "result";
var instance = new Mock<IGetTypeNameString>()
.Setup(x => x.For(It.IsAny<Type>(), out name))
.Returns(true)
.Create();
// Act
string resultName;
var result = instance.For(typeof(string), out resultName);
// Assert
Assert.True(result);
Assert.Equal("result", resultName);
}
As for how to achieve that with F#, I am completely lost. I tried something along the lines of
let name = "result"
let instance = Mock<IGetTypeNameString>().Setup(<# x.For(It.IsAny<Type>(), name) #>).Returns(true).Create();
which results in the quotation expression being underlined with an error message of
This expression was expected to have type IGetTypeNameString -> Quotations.Expr<'a> but here has type Quotations.Expr<'b>
Without any indication what types a and b are supposed to be, I have no clue how to correct this.
:?>
(It gets even wilder when I use open Foq.Linq; then the Error List window starts telling me about possible overloads with stuff like Action<'TAbstract> -> ActionBuilder<'TAbstract>, and I get even loster....)
Any assistance or explanation greatly appreciated!
Edit:
So, as stated here, byref/out parameters can not be used in code quotations. Can this be set up at all then in F#?

Answer 1

Foq supports setting up of C# out parameters from C# using the Foq.Linq namespace.
The IGetTypeNameString interface can be easily setup in F# via an object expression:
let mock =
{ new IGetTypeNameString with
member __.For(t,name) =
name <- "Name"
true
}
For declarations that have no analog in F#, like C#'s protected members and out parameters, you can also use the SetupByName overload, i.e.:
let mock =
Mock<IGetTypeNameString>()
.SetupByName("For").Returns(true)
.Create()
let success, _ = mock.For(typeof<int>)