type Mocked[T] = ref object
    expectations* : int
    calls*: seq[string]

method add_call(m : Mocked, param : string)  = # not generalized
    add(m.calls, param)
    m.expectations-=1

method expect(m : Mocked, num : int)  = # not generalized
    m.expectations+=num

method verify(m : Mocked)  = # not generalized
    if m.expectations > 0:
        raise newException(Defect, "Not all expectations met!")

type RealExecute = ref object


method execute(obj : RealExecute, process_name : string) =
    echo "impl"


method execute(obj : Mocked[RealExecute], process_name : string) =
    echo "mocked"
    obj.add_call(process_name)


var object_used_in_code : RealExecute
var object_used_in_ut : Mocked[RealExecute]
new object_used_in_code
new object_used_in_ut

proc exec[T](systemwrapper : T) =
    systemwrapper.execute("test")


object_used_in_ut.expect(3)
exec(object_used_in_code)
exec(object_used_in_ut)
exec(object_used_in_ut)
object_used_in_ut.verify()