---

name: xunit description: "Write, run, or repair .NET tests that use xUnit with the right package, CLI, and runner guidance. USE FOR: xUnit v2 or xUnit v3 projects; adding, running, debugging, or repairing xUnit tests; choosing between VSTest and Microsoft.Testing.Platform. DO NOT USE FOR: TUnit projects; MSTest projects. 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 solution or project with xUnit packages; respects the repo's AGENTS.md commands first."

xUnit.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 xUnit v2 or xUnit v3
• you need to add, run, debug, or repair xUnit tests
• the team is unsure whether a project is using VSTest or Microsoft.Testing.Platform

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

• TUnit projects
• MSTest projects
• generic test strategy with no xUnit-specific mechanics

Inputs

• the nearest AGENTS.md
• the test project file and package references
• the active runner model for the test project

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. Detect the active xUnit model before changing commands:
   • xunit usually means v2
   • xunit.v3 means v3
   • xunit.runner.visualstudio plus Microsoft.NET.Test.Sdk usually means VSTest compatibility is enabled
   • TestingPlatformDotnetTestSupport or UseMicrosoftTestingPlatformRunner means Microsoft.Testing.Platform is in play
2. Read the repo's real test command from AGENTS.md. If the repo has no explicit command yet, start with dotnet test PROJECT_OR_SOLUTION.
3. Keep the runner model consistent:
   • xUnit v2 usually runs through VSTest
   • xUnit v3 can run as a standalone executable with dotnet run
   • xUnit v3 can also integrate with Microsoft.Testing.Platform
   • do not mix VSTest-only switches into Microsoft.Testing.Platform runs
4. Run the narrowest useful scope first:
   • one project
   • one class
   • one trait
   • one method
5. Prefer [Theory] for stable data-driven coverage and [Fact] for single-path invariant checks.
6. Keep xunit.analyzers enabled when present. Fix analyzer findings instead of muting them casually.

Bootstrap When Missing

If xUnit is requested but not configured:

1. Detect current framework first:
   • rg -n "xunit(\\.v3)?|xunit\\.runner\\.visualstudio|TestingPlatformDotnetTestSupport|UseMicrosoftTestingPlatformRunner|TUnit|MSTest" -g '*.csproj' .
2. If the repo currently uses TUnit or MSTest, do not auto-migrate. Return status: not_applicable unless migration is explicitly requested.
3. For explicit xUnit adoption, add packages to the target test project:
   • dotnet add TEST_PROJECT.csproj package xunit.v3
   • optional VSTest bridge: dotnet add TEST_PROJECT.csproj package xunit.runner.visualstudio
4. Add repo test commands and runner notes to AGENTS.md.
5. Run dotnet test TEST_PROJECT.csproj or repo-defined xUnit command and return status: configured or status: improved.

Deliver

• xUnit tests that match the repo's active xUnit version and runner
• commands that work in local and CI runs
• focused verification before broader suite execution

Validate

• the chosen CLI matches the active runner model
• test filters or focused runs are valid for that runner
• tests use deterministic inputs and assertions
• xUnit-specific analyzers remain active unless the repo documents an exception

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/xunit.md
• references/patterns.md
• references/anti-patterns.md

Example Requests

• "Run this xUnit suite correctly."
• "Fix our xUnit v3 test command."
• "Add an xUnit regression test and keep CI compatible."