Agent Skill
Migrate Mstest V3 To V4 skill
migrate-mstest-v3-to-v4dotnet/skillsplugins/dotnet-test-migration/skills/migrate-mstest-v3-to-v4/SKILL.md
Use this skill before answering, planning, or editing any MSTest 3.x-to-4.x upgrade or post-upgrade failure. Triggers include "MSTest v4 breaking changes"; CS0507/CS0103/CS1061/CS1615; ExecuteAsync, CallerInfo, DisplayName, or custom TestMethodAttribute; ClassCleanupBehavior; ContainsKey; ThrowsExactly or ExpectedException; IsInstanceOfType out parameters; TestTimeout.Infinite; ManagedType; net6/net7 compatibility; TestCase.Id history; TestName in ClassInitialize; TreatDiscoveryWarningsAsErrors; discovery errors after a clean build; and MSTest.Sdk/MTP or vstest.console discovery changes. Do not use for v1/v2-to-v3 leftovers, framework conversion, runner-only migration, or a general .NET upgrade.
always on
179 tokname + description
once used
6,642 tokSKILL.md body
bundled files
0
repo stars
5.7kGitHub
Install the Migrate Mstest V3 To V4 skill
Skills CLI (Claude Code, Codex, Cursor and others)
npx skills add https://github.com/dotnet/skills --skill migrate-mstest-v3-to-v4
Claude Code, by hand (all projects)
git clone --depth 1 https://github.com/dotnet/skills.git /tmp/skills mkdir -p ~/.claude/skills cp -R /tmp/skills/plugins/dotnet-test-migration/skills/migrate-mstest-v3-to-v4 ~/.claude/skills/migrate-mstest-v3-to-v4
For one project only, copy the folder into .claude/skills/ in that project instead. The agent picks it up when a task matches its description.
What it costs your context
Agent Skills load in three steps. Tokens counted with the o200k tokenizer; your model's count will differ a little.
| When | What loads | Cost |
|---|---|---|
| Every session | Name and description | 179 tok |
| When the agent uses it | The SKILL.md instructions | 6,642 tok |
| Only if opened | No bundled files | — |
Until it is used, migrate-mstest-v3-to-v4 costs about 7.6× less than the median MCP server we measured (1,362 tokens on every turn). Installing all 114 skills from dotnet/skills would load 15,432 tokens of descriptions. Skills vs MCP study
Checks
- The instructions are over 5,000 tokens, the Agent Skills specification's guideline for SKILL.md.
- The instructions are over 500 lines; the specification suggests moving detail into reference files.
Checked 2026-10-22 · method
What's inside
The headings of its SKILL.md. Read the full file on GitHub.
- MSTest v3 -> v4 Migration
- First Action
- When to Use
- When Not to Use
- Inputs
- Decisions That Change the Result
- Response Guidelines
- Workflow
- Step 1: Assess the project
- Step 2: Update packages to MSTest v4
- Step 3: Resolve source breaking changes
- Step 4: Address behavioral changes
- Step 5: Verify
- Validation
- Related Skills
- Common Pitfalls
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