Mutations for Linq methods don't work

Describe the bug This code with the Linq method doesn’t mutate.

public int TestLinq(int count)
{ 
    var list = Enumerable.Range(1, count);
    return list.Last();
}

Also I tried to move Linq method from return statement.

public int TestLinq(int count)
{
   var list = Enumerable.Range(1, count);
   var last = list.Last();
   return last;
}

And also I tried another methods (First, FirstOrDefault). Unit test for this method.

[Test]
public void TestLinq_One_Equal()
{
    var r = _sl.TestLinq(5);
    Assert.AreEqual(5, r);
}

Expected behavior Linq method should be mutated Last to LastOrDefault (etc) and vice versa.

Desktop (please complete the following information):

• OS: Windows 10
• Type of project: core
• Framework Version: netcoreapp2.2
• Stryker Version: 0.11.0 (beta)

Additional context Others mutation for another methods works well.

[richardwerkman]

I have to say that the MutantOrchestator is one of the most complex parts of stryker so I think this might be a hard bug to fix. I’ve created a branch where I’ve cleaned the mutant orchestrator tests (579_call_linq_mutator). This makes TDD possible to target this bug. Maybe that could help. I will try to tackle this too if I find time soon.

[dupdob]

Fixed by PR #624. Manually tested on real project, but specific test added to the codebase