complexStub.swift

protocol Loader{
    func load(_ url: @autoclosure ()->(URL), completion: @escaping (URLResponse)->()) throws -> CancelToken
}

// Before
class LoaderStub: Loader {
    var loadAction: ((@autoclosure () -> (URL), (URLResponse) -> ()) throws -> CancelToken)?
    func load(_ url: @autoclosure...){...}
}

// After
class LoaderStub: Loader {
    lazy var loadAction = asNil(load)
    func load(_ url: @autoclosure...){...}
}