[kheisoty]

C# joins the languages crapper scores

tree-sitter-language-pack already ships the C# grammar, so this is a language module, discovery, and a coverage runner, with no new dependency.

What is an entry

• Methods with a body: a block or an => expression. Abstract methods, extern, and interface signatures are not.
• Property, indexer, and event accessors with a body, and expression-bodied properties, under the names the compiler gives them: get_Count, set_Item, add_Changed.
• Top-level statements, as one entry <Main>$, keyed under the project's root namespace (RootNamespace in the nearest .csproj, else the project file's name) so two projects' Program.cs do not share a key.
• Each minimal-API endpoint registered with a lambda (MapGet, MapPost, MapPut, MapPatch, MapDelete, Map, MapMethods) is its own entry named GET /users, with #2 for a second lambda on the same route, and its decisions are not charged to the enclosing entry. This is the Express rule from typescript.py; _claim moved to treesitter.py as claim_name so both share it.
• Constructors, operators, and finalizers are omitted, as crap4java omits constructors. Lambdas and local functions stay inside the enclosing entry.

What is a decision

crap4java's set spelled in C#: if, for, foreach, while, do, catch and its when filter, ?:, each switch section and its when guard, each switch-expression arm, && / ||; plus ??, ?., and and / or inside a pattern.

Discovery

.cs is csharp. obj/ is skipped (generated AssemblyInfo.cs, GlobalUsings.cs). *Tests.cs, *Test.cs, and any .cs inside a *.Tests / *.Test directory are test code.

Coverage

dotnet test <target> --collect:"XPlat Code Coverage" --results-directory target/coverage/csharp -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=lcov, once per .sln at the root, else once per test project. coverlet writes coverage.info; the runner renames it to lcov.info for the existing LCOV loader. A missing coverlet.collector reference is reported and scores 0%, like the other languages' missing tools.

Verification

• tests/test_csharp.py (10 tests) pins every rule above against small sources, plus the obj/test-file discovery; test_runners.py gains 5 tests for targets, the command vector, the rename, and the warnings; test_languages.py and test_cli.py gain the C# rows. pytest: 161 passed (the Babashka-dependent snapshot test was not run on this machine).
• Ran end to end on a .NET 10 solution of 57 files / 9.4k lines with 456 xUnit tests: 227 entries, coverage read from coverlet's LCOV, <Main>$ and 25 endpoint lambdas scored. One lambda's CC was checked by hand against the source (3 if, 1 ?:, 4 catch, 1 || → 10).

Note

mutator finds functions through crapper.discover and crapper.languages, so with this change it will see .cs files but has no test plan for them; a C# plan there would compile per mutant, which is what Stryker.NET exists to avoid. Happy to add a "skip csharp" guard in mutator if you prefer.

🤖 Generated with Claude Code