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jit-regression-test

Extract a standalone JIT regression test case from a given GitHub issue and save it under a JIT regression runner folder. USE FOR: creating JIT regression tests, extracting repro code from dotnet/runtime issues, "write a test for this JIT bug", "create a regression test for issue #NNNNN", converting issue repro to xunit test. DO NOT USE FOR: non-JIT tests (use standard test patterns), debugging JIT issues without a known repro, performance benchmarks (use microbenchmark skill).

Quality

90%

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The risk profile of this skill

SKILL.md
Quality
Evals
Security

Quality

Content

82%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A well-crafted, highly actionable skill: concrete paths, a real worked example, and an explicit decision rule for the one genuinely tricky judgment call (when a custom .csproj is required). Its weaknesses are modest — the simple-test guidance is stated three times, and there is no verification step showing how to build or run the new test to confirm it was added correctly.

Suggestions

Deduplicate the 'simple tests need no .csproj' guidance — state it once in Step 2 and replace the Tips entry with a build/verify command showing how to confirm the new test is picked up and passes.

Add a short validation step (e.g., the dotnet test / test runner command used for JIT regression tests) so the workflow ends with an explicit checkpoint.

Fix the worked example's ordering inconsistency (file-scoped namespace placed before the using directives, and an extra blank line after the license header) so the copy-paste template is stylistically uniform.

DimensionReasoningScore

Conciseness

The body is lean — it assumes Claude knows C#/xunit and never explains concepts — but there is minor redundancy: the 'no .csproj edits for simple tests' guidance appears in Step 2, again in Step 4, and a third time in Tips. That repetition is a trimmable instance matching anchor 4 ('efficient; minor instances that could be trimmed') rather than anchor 5's every-token-earns-its-place.

4 / 5

Actionability

Fully executable guidance: exact target paths, a copy-paste-ready C# skeleton, a real worked example (Runtime_99391) with license header and NoInlining idiom, and a complete custom .csproj XML sample with CLRTestEnvironmentVariable entries. This matches anchor 5's copy-paste-ready code covering the common cases.

5 / 5

Workflow Clarity

Steps 1-4 give a clear, correctly-ordered sequence with a decision rule for when a custom project is needed, and the warning block states when not to proceed. However there is no validation checkpoint telling Claude how to build/run the test to confirm it works after creation, which is exactly anchor 4's 'most checkpoints present; minor validation gaps' — not 5, which requires explicit validation steps, and not 3, since the sequence itself is complete and this is not a destructive/batch operation.

4 / 5

Progressive Disclosure

The body is a well-organized single file with clear section headers, and no bundle files exist (no references/, scripts/, or assets/), so all referenced paths are in-repo dotnet/runtime paths, which is appropriate. It exceeds the under-50-line simple-skill exception, and content like the full worked example could arguably live in a references/ file, so it fits anchor 4 ('good structure; most content appropriately placed; minor organization gaps') rather than anchor 5's ideal overview-plus-signaled-references split.

4 / 5

Total

17

/

20

Passed

Description

95%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description: concrete two-part 'what', natural quoted trigger phrases for 'when', and an explicit DO NOT USE FOR boundary that disambiguates sibling skills. The only weakness is that the capability inventory is slightly thinner than the body's actual coverage (csproj conventions, license headers), which keeps specificity at 4 rather than 5.

DimensionReasoningScore

Specificity

The description states two concrete, specific actions ('Extract a standalone JIT regression test case from a given GitHub issue and save it under a JIT regression runner folder') with domain-precise nouns, but the action list is narrower than a fully comprehensive inventory (no mention of csproj creation or test conventions that the body covers). It sits between anchor 3 (1-2 concrete actions) and anchor 5 (multiple actions, comprehensive coverage), matching anchor 4's 'several specific actions; minor gaps in coverage'.

4 / 5

Completeness

It explicitly answers both 'what' (extract a standalone JIT regression test from a GitHub issue and save it under the runner folder) and 'when' (a USE FOR list of concrete trigger phrases) plus a DO NOT USE FOR exclusion list — matching anchor 5's 'clearly and explicitly answers both what AND when with concrete trigger phrases', with the negative boundary exceeding the anchor.

5 / 5

Trigger Term Quality

The USE FOR list includes natural user phrasings with synonyms: 'creating JIT regression tests', 'extracting repro code from dotnet/runtime issues', "'write a test for this JIT bug'", "'create a regression test for issue #NNNNN'", 'converting issue repro to xunit test'. This matches anchor 5's comprehensive natural-term coverage including quoted user-style phrasings and repo-specific synonyms.

5 / 5

Distinctiveness Conflict Risk

The niche is narrow (JIT regression tests in dotnet/runtime) and the DO NOT USE FOR clause explicitly redirects the nearest conflicting cases (non-JIT tests, debugging without a repro, performance benchmarks) to their appropriate skills. Clear niche with distinct triggers and minimal conflict risk, matching anchor 5.

5 / 5

Total

19

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository

dotnet/runtime

Path

.github/skills/jit-regression-test/SKILL.md

Reviewed

Table of Contents

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