dotnet-coverage

name

dotnet-coverage

description

Generate a code coverage report for a .NET project or solution via `dotnet test --collect:"XPlat Code Coverage"` (the Coverlet collector), scoped to the test selector given (same selector syntax as the `dotnet-test` skill), then read the generated `coverage.cobertura.xml` to report the exact line-coverage percentage for the specific class(es) touched — using that same file's per-line `hits` data to show which lines/branches are still uncovered. Invoke as `/dotnet-coverage <selector> [TargetClass1,TargetClass2,...]`, or `/dotnet-coverage` with no argument to run the full suite and report whole-solution coverage. Use whenever the user wants to check, or verify a coverage bar (e.g. "at least 80% line coverage") for a class or set of classes, instead of eyeballing `dotnet test` output.

.NET Coverage

Run Coverlet (via dotnet test's built-in "XPlat Code Coverage" collector) against a scoped (or full) test run and report the exact, measured coverage percentage for the class(es) the user cares about. This skill only measures and reports coverage — it does not add tests or modify source/test code unless asked to as a follow-up.

Step 1 — Determine the test scope

If the user gave a selector, it uses the exact same syntax as the dotnet-test skill's Step 1 table (class, class+method, several classes/methods, wildcard/namespace pattern, trait/category expression, project/solution path). If no selector was given, run the whole suite.

Important: coverage is only recorded for code actually exercised by the tests that ran in this invocation. If a class under test is covered by tests spread across multiple test classes, the selector must include all of them — scoping to just one will undercount that class's real coverage. When in doubt about whether a selector covers everything relevant to the target class, prefer a broader selector (e.g. the whole namespace, or the full suite) over a narrow one.

Step 2 — Determine the target class(es) to report on

• If the user (or the calling skill) explicitly named target class(es), use those.
• Otherwise, infer them from the test selector by convention: a test class FooTests targets Foo, FooTests.TestSomething still targets Foo. For several test classes, infer one target class per test class.
• If the selector is a wildcard, namespace pattern, or trait/category expression, target classes can't be inferred by name — report on every class touched by that run (Step 4 already surfaces all of them), or ask the user which class(es) they care about if the run touches many unrelated ones.

Step 3 — Run the coverage collection

dotnet test [<path-to-.sln-or-.csproj>] --filter "<expression>" --collect:"XPlat Code Coverage" --results-directory ./TestResults

Omit --filter "<expression>" entirely to run the full suite.

Notes:

• This requires the coverlet.collector NuGet package on the test project(s) being run — it ships by default in projects created from the mstest/nunit/xunit dotnet new templates. If a test project is missing it, --collect silently produces nothing to read; check the .csproj for <PackageReference Include="coverlet. collector" .../> first, and if it's absent, tell the user to add it (dotnet add package coverlet.collector) rather than reporting a false 0%.
• Each run writes a new GUID-named subfolder under the results directory containing coverage.cobertura.xml. Delete the results directory first (rm -rf ./TestResults) so there's no risk of reading a stale report left over from an earlier run — this is the .NET equivalent of the clean goal wiping JaCoCo's previous jacoco.exec.
• If the build or test run fails, report that failure — don't attempt to read a coverage report that wasn't (re)generated.

Step 4 — Read the exact coverage from coverage.cobertura.xml

Find the generated file (find ./TestResults -name coverage.cobertura.xml, since it's nested under a run-guid folder) and read it. Its structure is:

<coverage line-rate="..." branch-rate="...">
  <packages>
    <package name="...">
      <classes>
        <class name="MyProject.Services.Foo" filename="..." line-rate="..." branch-rate="...">
          <methods>...</methods>
          <lines>
            <line number="12" hits="1" branch="false"/>
            <line number="13" hits="0" branch="true" condition-coverage="50% (1/2)"/>
            ...
          </lines>
        </class>
      </classes>
    </package>
  </packages>
</coverage>

For each target class from Step 2, find its <class> element (match the name attribute, the fully-qualified type name, e.g. MyProject.Services.Foo; nested/partial types may appear as separate <class> entries) and compute:

line coverage %   = count(<line hits!="0">) / count(<line>) * 100
branch coverage % = count(<line branch="true" hits!="0">) / count(<line branch="true">) * 100   (n/a if there are no branch lines, e.g. records with no conditional logic)

Prefer counting <line> elements directly over trusting the pre-computed line-rate/branch-rate attributes at face value — they're accurate for a single <class> entry, but if a target class is split across multiple <class> entries (partial classes), sum the underlying <line> counts across all of them rather than averaging the attributes. Use the XML, not a generated HTML report, as the source of truth, exactly as the java-coverage skill reads JaCoCo's CSV rather than its HTML tables.

If a target class doesn't appear in the XML at all, it means no code in that class executed during this run (either it's dead/unreachable from the tests that ran, or the selector didn't include tests that exercise it) — report 0%, not an error.

Step 5 — Report results

State, per target class, the line coverage percentage (and branch coverage if relevant to the discussion), computed from actual XML numbers — never estimate or guess. If the user's bar is "at least N%": say clearly whether each class meets it.

For classes under the bar, point to exactly what's uncovered directly from the same XML — no separate HTML report is needed, unlike JaCoCo, since Cobertura's <lines> list already carries per-line hit data: every <line number="N" hits="0"/> under that class is an uncovered line, and every <line branch="true" hits="1" condition-coverage="50% (1/2)"/> is a partially-covered branch. List those exact line numbers when the user wants to know precisely which lines/branches to target with new tests, rather than just the aggregate percentage.

Do not add tests, modify source/test code, or re-run anything to try to raise coverage — that's a follow-up the user (or another skill) drives explicitly.