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test-driven-development

Implements a feature or bug fix test-first: write one failing test, run it and watch it fail, write the minimal code to pass, then refactor with the tests green. Use when a change alters code behavior: a new feature, a bug fix, or a behavior change, whether the request comes alone or through delivery-flow.

71

Quality

89%

Does it follow best practices?

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SKILL.md
Quality
Evals
Security

Quality

Content

85%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.

Excellent actionable content: executable examples, explicit validation checkpoints with feedback loops, and clean one-level-deep reference structure. The one weakness is redundancy — the anti-rationalization material is covered twice and the core rule is restated several times, so the file could be tightened meaningfully.

Suggestions

Merge the "Common Rationalizations" table and "Red Flags" list into a single excuse-to-response table — they cover the same ground twice and account for roughly 40 lines of duplication.

Replace the graphviz dot diagram with a simple ordered text cycle (RED → verify fail → GREEN → verify pass → REFACTOR → repeat) — the dot source spends tokens on layout and styling without adding instructional value.

State the "delete the code and start over" rule once (e.g., in The Iron Law) and cut its restatements in Red Flags and Final Rule.

DimensionReasoningScore

Conciseness

The body is dense and prescriptive rather than explaining known concepts, but the 13-item "Red Flags" list substantially duplicates the 11-row "Common Rationalizations" table, the "delete and start over" rule is restated in Iron Law, Red Flags, and Final Rule, and the graphviz dot source spends tokens on rendering details.

3 / 5

Actionability

Fully executable throughout: real TypeScript test examples with Good/Bad contrasts, concrete commands ("npm test path/to/test.test.ts"), and a complete worked bug-fix example showing RED failure output through GREEN pass.

5 / 5

Workflow Clarity

The Red-Green-Refactor cycle is explicitly sequenced with mandatory "Verify RED"/"Verify GREEN" checkpoints, error-recovery feedback loops ("Test errors? Fix error, re-run until it fails correctly"; "Test fails? Fix code, not test"), and a final verification checklist.

5 / 5

Progressive Disclosure

The body keeps the core process inline while offloading detailed test-writing rules to a well-signaled, existing, one-level-deep reference ("read [references/writing-good-tests.md] for the rules that keep tests honest") with a bullet summary of its contents.

5 / 5

Total

18

/

20

Passed

Description

88%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: it names the concrete four-step TDD cycle, answers both what and when explicitly in third person, and uses natural trigger phrases. Its only gaps are a few missing synonyms (e.g., TDD, test-driven) and trigger breadth that slightly overlaps general coding skills.

DimensionReasoningScore

Specificity

"write one failing test, run it and watch it fail, write the minimal code to pass, then refactor with the tests green" lists four concrete actions covering the complete red-green-refactor cycle — comprehensive for this skill's capability.

5 / 5

Completeness

"Implements a feature or bug fix test-first..." clearly answers what it does, and "Use when a change alters code behavior: a new feature, a bug fix, or a behavior change..." explicitly answers when with concrete trigger phrases. Third-person voice is used throughout.

5 / 5

Trigger Term Quality

Natural terms like "test-first", "failing test", "new feature", "bug fix", and "behavior change" are present, but common synonyms such as "TDD", "test-driven", or "write unit tests" are missing.

4 / 5

Distinctiveness Conflict Risk

The test-first methodology is a clear niche with distinct triggers, but generic coding terms like "a bug fix" and "a new feature" create minor overlap risk with closely related delivery-flow and general coding skills.

4 / 5

Total

18

/

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

tesslio/tessl-eval-demo

Path

02-mutation/versions/record-red/sdlc-implementation/skills/test-driven-development/SKILL.md

Reviewed

Table of Contents

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