I did a spike once for xBehave.net which would allow this in .NET 4.0+. The `scenario` object which is passed as an argument to each step expression is an `ExpandoObject` typed as `dynamic`. I'd love to come up with a solution which doesn't have the issue noted in the code.

xBehave.net with ExpandoObject

[Scenario]
public void PushingAnElementOntoAStack() // No parameters :-D
{
    "Given an element"
        .Given(scenario => scenario.Element = 11);

    "And a stack"
        .And(scenario => scenario.Stack = new Stack<int>());

    "When pushing the element onto the stack"
        .When(scenario => scenario.Stack.Push(element));

    // NOTE: I would like to write this without the cast but I can't because 
    // Should() is an extension method on object provided by FluentAssertions and
    // it is not possible to call extension methods on dynamic :-(
    "Then the element should be at the top of the stack"
        .And(scenario => ((int)scenario.Peek()).Should().Be(element));
}

Currently, this code has to be written as shown at https://github.com/xbehave/xbehave.net#how-do-i-use-it