A guide to using Coverlet, an open-source .NET toolchain that measures which lines and branches are exercised by tests. It helps choose the appropriate Coverlet driver for the test runner and workflow.

Use it to add line or branch coverage to .NET tests, choose between Coverlet’s collector, MSBuild, or console drivers, and run coverage in CI.

Teams often get inconsistent coverage commands or reports when the collector, MSBuild integration, and standalone tool are mixed up. This provides a clear setup for local or continuous-integration test runs.

coverlet — Skill for Claude Code and Codex by managedcode

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add managedcode/dotnet-skills --skill coverlet

Clone the repo

git clone --depth 1 https://github.com/managedcode/dotnet-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/managedcode/dotnet-skills/coverlet.svg)](https://agentmods.dev/skills/managedcode/dotnet-skills/coverlet)

Your own site

<a href="https://agentmods.dev/skills/managedcode/dotnet-skills/coverlet"><img src="https://agentmods.dev/badge/skills/managedcode/dotnet-skills/coverlet.svg" alt="Measured on agentmods" height="20"></a>

Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,167 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00114	$0.01167
Opus 5	$0.00057	$0.00583
Sonnet 5	$0.00023	$0.00233
Haiku 4.5	$0.00011	$0.00117

Measured 4d ago against content hash fdb5e40f553f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

coverlet scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

catalog/Testing/Coverlet/skills/coverlet/SKILL.md · 115 lines

How it starts

The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Coverlet for .NET

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

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

Workflow

Choose the driver deliberately:
- coverlet.collector for VSTest dotnet test --collect
- coverlet.msbuild for MSBuild property-driven runs
- coverlet.console for standalone scenarios
Add coverage packages only to test projects.
Do not mix coverlet.collector and coverlet.msbuild in the same test project.
Pair raw coverage collection with ReportGenerator only when humans need rendered reports.

Bootstrap When Missing

If coverage is not configured yet:

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

Read the full file on GitHub · 115 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

4d ago First seen · 115 lines · 114 tokens per session scan A fdb5e40f553f

Subscribe to this mod's changes

coverlet is a skill published in the GitHub repository managedcode/dotnet-skills (477 stars, last pushed 2d ago), licensed MIT. It adds 114 tokens to every session and 1,167 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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