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xUnit -> MSTest Migration · dotnet | DecimalAI

testingby dotnet

xUnit -> MSTest Migration

dotnet/migrate-xunit-to-mstest

Source dotnet/skills ↗License MIT

Convert .NET test projects from xUnit.net v2 or v3 to MSTest v4.

SkillScore61Maintained

Automatic

Coding pack

Last verified 9/1/2026

What it changes

Passed 9 of 14 test cases with the skill, and 7 of 14 without it.

Without skill48%

With skill61%

Checks it passed that the model alone missed

Omits the assembly-level Parallelize attribute.
Uses Assert.Throws to replace xUnit Assert.ThrowsAny.
Uses Assert.ThrowsExactly to replace xUnit Assert.Throws.

and 1 more in the full report

4 fixed10 passed either way8 still failing1 broke

Pass-rate lift: +13 pp
Tokens: +106%
Agent turns: 0%
Response time: -41%

Model gemini-3.6-flashMeasured 9/1/2026v214 of 23 cases passed with skill · 14 comparable

Tokens, turns and time describe resource use, not a dollar price.

Use this skill

Save it into your project's skills folder. Claude Code picks it up in its next session.

curl -fsSL --create-dirs -o .claude/skills/dotnet-migrate-xunit-to-mstest/SKILL.md https://app.decimal.ai/s/dotnet-migrate-xunit-to-mstest/SKILL.md

Want it pinned and updatable? pip install "decimalai>=0.15", then decimalai skills add dotnet-migrate-xunit-to-mstest, and start Claude Code with claude --plugin-dir "$(git rev-parse --show-toplevel)/.agents"

1 · One-time — install the CLI (docs ↗)

pip install "decimalai>=0.15"

2 · Get the skill — writes .agents/skills/dotnet-migrate-xunit-to-mstest/ and pins it in .decimal/skills.lock

decimalai skills add dotnet-migrate-xunit-to-mstest

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/dotnet-migrate-xunit-to-mstest/SKILL.md https://app.decimal.ai/s/dotnet-migrate-xunit-to-mstest/SKILL.md

Raw file: /s/dotnet-migrate-xunit-to-mstest/SKILL.md ↗ · machine-readable summary at /s/dotnet-migrate-xunit-to-mstest.json ↗

Safety checks: 3 of 3 passed

Code scan CleanIntent PassedContent Clean

See it in action

One of 4 test cases the skill fixed. Same model, same prompt, with and without the skill.

1 of 4

Prompt

Convert this xUnit test assertion to MSTest v4: `var ex = Assert.ThrowsAny<KeyNotFoundException>(() => cache.Get("missing"));`. Base models might map `ThrowsAny` to `ThrowsExactly`. Which MSTest v4 assertion method allows derived exception types?

What was checked, without and with the skill
Checked	Without skill	With skill
Uses Assert.Throws to replace xUnit Assert.ThrowsAny.	Missed	Passed

case-08 · gemini-3.6-flash · 9/1/2026 · answers are capped and redacted

What's inside

The instructions your model reads when the skill loads.

SKILL.md176 lines2 files

xUnit -> MSTest Migration

Convert xUnit.net v2 or v3 tests to MSTest v4 without changing the target framework or test platform. A successful migration builds, discovers the same tests, and preserves pass/fail results and execution semantics.

Scope

Use this skill only when the project contains xUnit packages or source and the user wants MSTest. If the project already uses MSTest and contains no xUnit tests, report that no framework migration is needed and make no changes.

Do not combine this framework conversion with a target-framework upgrade or VSTest/MTP migration. Complete and verify one migration before starting another.

Workspace Contract

Continue after skill activation. Search the current working directory for the staged project and source; never look for user files under this skill's base directory.
Open the literal paths returned by glob/search. If one reader or patch tool rejects a path that was just found, retry with another available tool. Do not ask the user for a path until current-workspace discovery is exhausted.
Classify by the requested deliverable: "convert this project" means edit, build, and test; "give me a plan" or "how would I convert it?" means answer. Do not replace execution with "please provide the files" when files are present.
The final response must state the source xUnit version, preserved runner, changed files, each high-risk semantic mapping applied, and actual test counts. Assertions about fixture lifetime, Owner mapping, cancellation, or parallelization must be visible in the resulting source, not only prose.

Response Mode

Full migration request: inspect the project, make the edits, build, and run tests. Do not stop after giving a plan.
Focused compile error or API question: inspect the relevant code and apply only that mapping. Do not narrate the entire workflow.
Unsupported target framework: stop before changing packages. MSTest v4 requires .NET 8+ or .NET Framework 4.6.2+ for test applications; offer a separately approved TFM upgrade or MSTest v3 as the intermediate target.

Decisions That Change the Result

Apply these before the mechanical mapping:

Detected state	Required action
No xUnit package, namespace, attribute, or fixture remains	Stop. Make no file changes, report that migration is unnecessary, and run the existing `dotnet test` command once to prove the already-MSTest project is healthy.
Source uses VSTest	Keep the existing VSTest property/configuration. Prefer retaining and updating a source project's explicit `Microsoft.NET.Test.Sdk` pin; a repository that intentionally relies on the MSTest metapackage's transitive dependency may keep that convention. Do not introduce MTP properties.

Track record

Benchmark

9 / 14

test cases passed, vs 7 / 14 without

Adoption

Users: 0
Times used: 0

Safety and source details

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v5 — 9/1/2026

View 15 scanner checks

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

dotnet / skills

plugins/dotnet-test-migration/skills/migrate-xunit-to-mstest/SKILL.md

View on GitHub ↗

License MITImported 9/1/2026Version v2Bundled 1 file

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See it in action

What's inside

xUnit -> MSTest Migration

Scope

Workspace Contract

Response Mode

Decisions That Change the Result

Track record

Benchmark

Adoption

SkillSafety

Source

Other skills for the same job

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