xUnit.net

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."