Linq expressions with no replacements break builds

I know the Linq mutator was only added recently but there appears to be issues with the mutations that go from something to ‘none’ (OrderBy, OrderByDescending, Reverse, etc), where the replacement is not able to build.

For example, the following line:

someList.OrderBy(i => i.ToString());

is mutated to:

someList.(i => i.ToString());

Perhaps the following options could be considered for fixes?

// Remove the call
someList;

// Find a valid anti-call (may not be always possible)
someList.OrderByDescending(i => i.ToString());

// Don't mutate (when no reasonable mutation exists)
someList.OrderBy(i => i.ToString());

I’ve put together a small reproduction:

    public class Class1
    {
        public void DoIt()
        {
            new List<object>().OrderBy(o => o.ToString());
        }
    }

And attached some logs: stryker-debug.log

Thanks!

[richardwerkman]

Thanks for your notice. This mutation was meant to remove the call as you said. It seems nobody noticed this before since the mutations are just rollbacked and this is not shown (unless debugging is enabled). I’ll look into this too!

[rouke-broersma]

I agree