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testland/fast-check-testing

Authors property-based tests in JavaScript / TypeScript using fast-check - wires `fc.assert(fc.property(arbitrary, ...))`, picks arbitraries (`fc.integer`, `fc.string`, `fc.array`, `fc.tuple`, `fc.record`), uses `.map()` / `.chain()` / `.filter()` to build domain arbitraries, and integrates with Jest / Vitest / Mocha / Jasmine / AVA / Tape. Use when a JS/TS codebase needs PBT to catch edge cases - fast-check has been used to find bugs in major libraries (`query-string`, etc.) and is trusted by Jest, Jasmine, fp-ts, Ramda.

80

Quality

100%

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Overview
Quality
Evals
Security
Files

Quality

Content

100%

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

A well-structured body that stays lean via progressive disclosure, leads with executable fast-check patterns, and includes an explicit verification feedback loop. It hits the top anchor on every dimension with only minor redundancy from the closing References section re-listing inline pointers.

DimensionReasoningScore

Conciseness

The body is lean, delegates the arbitrary catalog, shrinking, and stateful/async details to references, and avoids explaining generic concepts Claude already knows; the brief readme quotes establish sourcing rather than padding, matching the 'lean and efficient; every token earns its place' anchor.

3 / 3

Actionability

Provides multiple complete, copy-paste-ready code blocks (Mocha `fc.assert(fc.property(...))`, Vitest reverse-involution, the worked codec round-trip with `fc.record`) plus concrete install commands, matching the 'fully executable code/commands; copy-paste ready' anchor.

3 / 3

Workflow Clarity

The 8-step 'How to use' sequence includes an explicit verify/replay feedback loop (step 7: re-run all cases, replay the failing seed, and if it still fails the fix or property is wrong — correct and re-run), and the worked example traces failure→shrink→replay→fix, matching the 'clear sequence with explicit validation steps; feedback loops' anchor.

3 / 3

Progressive Disclosure

SKILL.md is an overview with well-signaled one-level-deep references to references/arbitraries.md, references/shrinking-and-reproducibility.md, and references/stateful-and-async.md — all three files exist in the bundle — with content appropriately split, matching the 'clear overview with well-signaled one-level-deep references' anchor.

3 / 3

Total

12

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12

Passed

Description

100%

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, third-person description with concrete actions, explicit 'Use when' trigger guidance, and a distinct JS/TS fast-check niche. Its only weakness is mild verbosity from the implementation-token dump and the marketing-style trust list, but neither crosses into vague fluff or over-claim.

DimensionReasoningScore

Specificity

Lists multiple concrete actions in third person — 'Authors property-based tests', 'wires `fc.assert(fc.property(arbitrary, ...))`', 'picks arbitraries (`fc.integer`, `fc.string`, ...)', 'uses `.map()` / `.chain()` / `.filter()`', 'integrates with Jest / Vitest / Mocha / Jasmine / AVA / Tape' — matching the 'lists multiple specific concrete actions' anchor.

3 / 3

Completeness

Explicitly answers both what (authors/wires/picks/integrates) and when via a 'Use when a JS/TS codebase needs PBT to catch edge cases' trigger clause, satisfying the 'clearly answers both what AND when' anchor.

3 / 3

Trigger Term Quality

Good coverage of natural terms a user would say — 'property-based tests', 'fast-check', 'JavaScript / TypeScript', 'catch edge cases', and the major runner names — rather than only jargon; this exceeds the 'some relevant keywords but missing common variations' anchor.

3 / 3

Distinctiveness Conflict Risk

Occupies a clear niche (fast-check PBT for JS/TS) with distinct triggers unlikely to fire for sibling skills like hypothesis-testing (Python) or schemathesis-fuzzing, matching the 'clear niche with distinct triggers' anchor.

3 / 3

Total

12

/

12

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.

Validation16 / 16 Passed

Validation for skill structure

No warnings or errors.

Reviewed

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