/coverlet

name: coverlet
description: "Use the open-source free `coverlet` toolchain for .NET code coverage. Use when a repo needs line and branch coverage, collector versus MSBuild driver selection, or CI-safe coverage commands. USE FOR: coverlet setup; CI line or branch coverage; choosing between collector and MSBuild drivers. DO NOT USE FOR: coverage report rendering by itself; repos that intentionally use a different coverage engine. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made."
compatibility: "Requires a .NET test project or solution; respects the repo's `AGENTS.md` commands first."

Coverlet for .NET

Diagnostic Output Budget

Keep native test progress and ANSI visible; use the detected runner's supported flags (`--progress on --ansi on` for MTP/TUnit), not MTP switches on VSTest. Keep console logs at `Warning` or higher and one concise final summary. Do not replay progress redraws, successful-test output, or Information/Debug/Trace logs into model context. On failure/crash, show only the failing test/resource, root error, and relevant stack frames; deduplicate and cap each diagnostic response at 80 lines / 8 KiB. Never dump entire console/host/browser logs, HTML, TRX, or crash artifacts. Keep necessary artifacts size-bounded outside context, link them, and inspect exact bounded excerpts. Preserve the runner exit code through capture/filtering; disclose truncation. Silence alone does not establish a hang.

Trigger On

• the repo uses or wants `coverlet`
• CI needs line or branch coverage for .NET tests
• the team needs to choose between `coverlet.collector`, `coverlet.msbuild`, or `coverlet.console`

Value

• produce a concrete project delta: code, docs, config, tests, CI, or review artifact
• reduce ambiguity through explicit planning, verification, and final validation skills
• leave reusable project context so future tasks are faster and safer

Do Not Use For

• coverage report rendering by itself
• repos that intentionally use a different coverage engine

Inputs

• the nearest `AGENTS.md`
• active runner model: VSTest or Microsoft.Testing.Platform
• target test projects

Quick Start

1. Read the nearest `AGENTS.md` and confirm scope and constraints. 2. Run this skill's `Workflow` through the `Ralph Loop` until outcomes are acceptable. 3. Return the `Required Result Format` with concrete artifacts and verification evidence.

Workflow

1. Choose the driver deliberately:

• `coverlet.collector` for VSTest `dotnet test --collect`
• `coverlet.msbuild` for MSBuild property-driven runs
• `coverlet.console` for standalone scenarios

2. Add coverage packages only to test projects. 3. Do not mix `coverlet.collector` and `coverlet.msbuild` in the same test project. 4. Pair raw coverage collection with `ReportGenerator` only when humans need rendered reports.

Bootstrap When Missing

If coverage is not configured yet:

1. Detect current state:

• `rg -n "coverlet\\.(collector|msbuild)|CollectCoverage|XPlat Code Coverage" -g '*.csproj' -g '*.props' -g '*.targets' .`
• `dotnet tool list --local`
• `dotnet tool list --global`
• `command -v coverlet`

2. Install exactly one driver path:

• VSTest collector: `dotnet add TEST_PROJECT.csproj package coverlet.collector`
• MSBuild driver: `dotnet add TEST_PROJECT.csproj package coverlet.msbuild`
• Console tool: `dotnet new tool-manifest` (if missing) and `dotnet tool install coverlet.console`

3. Record one concrete local and CI command in `AGENTS.md`:

• collector: `dotnet test TEST_PROJECT.csproj --collect:"XPlat Code Coverage"`
• msbuild: `dotnet test TEST_PROJECT.csproj /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura`
• console: `dotnet tool run coverlet TEST_ASSEMBLY.dll --target "dotnet" --targetargs "test TEST_PROJECT.csproj --no-build"`

4. Run the chosen command once and return `status: configured` or `status: improved`. 5. If another coverage engine already owns coverage for this repo, return `status: not_applicable`.

Deliver

• explicit coverage driver selection
• reproducible coverage commands for local and CI runs

Validate

• coverage driver matches the runner model
• coverage files are stable and consumable by downstream reporting

Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

1. Plan first (mandatory):

• analyze current state
• define target outcome, constraints, and risks
• write a detailed execution plan
• list final validation skills to run at the end, with order and reason

2. Execute one planned step and produce a concrete delta. 3. Review the result and capture findings with actionable next fixes. 4. Apply fixes in small batches and rerun the relevant checks or review steps. 5. Update the plan after each iteration. 6. Repeat until outcomes are acceptable or only explicit exceptions remain. 7. If a dependency is missing, bootstrap it or return `status: not_applicable` with explicit reason and fallback path.

Required Result Format

• `status`: `complete` | `clean` | `improved` | `configured` | `not_applicable` | `blocked`
• `plan`: concise plan and current iteration step
• `actions_taken`: concrete changes made
• `validation_skills`: final skills run, or skipped with reasons
• `verification`: commands, checks, or review evidence summary
• `remaining`: top unresolved items or `none`

For setup-only requests with no execution, return `status: configured` and exact next commands.

Load References

• [references/commands.md](references/commands.md)
• [references/patterns.md](references/patterns.md)
• [references/coverlet.md](references/coverlet.md)

Example Requests

• "Add Coverlet to this .NET solution."
• "Choose the right Coverlet driver for CI."