public void no_conversion_errors_but_the_action_blows_up()
{
var ex = new NotImplementedException();
theLineGrammar.Expect(x => x.Execute(values, context)).Throw(ex);
afterExecuting();
context.AssertTheOnlyResultIs(new StepResult(values.id, ResultStatus.error)
{
error = ex.ToString(), position = thePosition
});
}