[samtrion]

Problem

The latest Stryker run on codebuilder reports 20 NoCoverage mutants ("Not covered by any test") out of 503 created. The private nested ScopeHandler struct in CSharpCodeBuilder.Scope.cs defines Equals(object), Equals(ScopeHandler), GetHashCode() and ==/!=. No test touches them and they are unreachable from outside: Scope()/ScopeLine() return IDisposable and the type is private.

Root cause

The struct implements IEquatable<ScopeHandler> and the operators, most likely to satisfy analyzer rules for structs (not proven, there are no suppressions in the repo). The members are dead code.

Change

private readonly struct ScopeHandler : IDisposable, IEquatable<ScopeHandler> becomes private sealed class ScopeHandler : IDisposable with only the constructor and Dispose. The five equality members and their docs are removed (4 lines added, 40 removed).

Before / After

metric	before	after
mutation score	91.94 %	93.21 %
mutants created	503	499
NoCoverage	20	15
CompileError	70	70
run time	3m21s	3m20s

After run (single run, branch): https://github.com/dailydevops/codebuilder/actions/runs/40805882274. About 5 of the original 20 NoCoverage mutants sat in the removed members; the remaining 15 are elsewhere.

Risk / what this does not change

Behaviour is unchanged: the type is private and always returned as IDisposable. The struct was already boxed on return, so there is no extra allocation in practice. Locally, the unit tests pass (395/395, net10.0) and the library compiles with 0 warnings.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.15%. Comparing base (0caae59) to head (176eb45).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #443      +/-   ##
==========================================
+ Coverage   91.76%   93.15%   +1.39%     
==========================================
  Files          15       15              
  Lines         340      336       -4     
  Branches      100       99       -1     
==========================================
+ Hits          312      313       +1     
+ Misses         17       12       -5     
  Partials       11       11              

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