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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.

76

Quality

95%

Does it follow best practices?

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The canonical home for this skill is test-driven-development in tesslio/tessl-eval-demo

SKILL.md
Quality
Evals
Security

Quality

Content

100%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.

An exemplary lean process skill: a crisp five-step loop with validation checkpoints, corrective feedback for each failure mode, hard rules, and a done checklist, with test-writing detail correctly deferred to a single clearly-signaled reference file. No verbosity or structure issues found.

DimensionReasoningScore

Conciseness

Every line is instruction ("Write the simplest production code that makes it pass. Add nothing the test does not need.") with zero concept explanation or padding; it assumes Claude's competence down to "Run the project's test command" without naming a framework. Matches the lean anchor, not the minor-over-explanation anchor at 4.

5 / 5

Actionability

As an instruction-only skill the guidance is fully executable: exact steps, decision criteria ("The test must fail because the behavior is missing, not because of a typo or a missing import"), and recovery actions for the common failure modes ("If it passes, it tests nothing new: change the test"). Covers the common cases the anchor-5 analog asks for.

5 / 5

Workflow Clarity

The 5-step cycle is clearly sequenced with explicit validation checkpoints (watch it fail, run the full suite with no errors or warnings, run again after refactor), feedback loops for error recovery, and a final "Before you say it is done" checklist. Not a destructive/batch operation, so no cap applies.

5 / 5

Progressive Disclosure

The ~30-line body keeps the cycle inline and moves detailed test-writing guidance to a well-signaled one-level-deep reference ("When writing or changing a test, read references/writing-good-tests.md"); the file exists on disk, has its own load trigger, and no nested references. Clearly matches the well-split overview anchor rather than the minor-gaps anchor at 4.

5 / 5

Total

20

/

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 enumerates the complete test-first cycle concretely and pairs it with an explicit use-when clause carrying natural trigger phrases. Its only weaknesses are the absence of common synonyms (TDD, unit test) and a broad code-change trigger that could overlap with general coding skills.

Suggestions

Add natural synonyms to the trigger clause, e.g. 'Use when asked to write tests first, do TDD, or add unit tests for a change'.

Narrow the when clause slightly so it does not fire on every code change, e.g. tie it to methodology requests or workflows where test-first order matters, reducing overlap with general implementation 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" enumerates multiple specific concrete actions covering the entire cycle comprehensively, matching the anchor-5 example's structure rather than the minor-gaps coverage of anchor 4.

5 / 5

Completeness

Explicitly answers what ("Implements a feature or bug fix test-first: write one failing test, run it and watch it fail... refactor") and when ("Use when a change alters code behavior: a new feature, a bug fix, or a behavior change..."), mirroring the anchor-5 example's what-plus-concrete-trigger structure. Not anchor 4, since the when clause is explicit and specific rather than improvable.

5 / 5

Trigger Term Quality

"a new feature, a bug fix, or a behavior change" are natural phrases users would say, giving good coverage, but common synonyms like "TDD", "unit test", or "write the test first" are absent. Fits anchor 4 (a few natural terms missing) rather than the synonym-and-extension completeness of anchor 5, and clearly above anchor 3's missing-variations level.

4 / 5

Distinctiveness Conflict Risk

The test-first methodology is a clear, distinct niche with its own action verbs, but the when clause ("a change alters code behavior") fires on essentially all code work, creating minor overlap risk with general implementation or delivery skills. Mostly distinct with minor overlap matches anchor 4; not anchor 3, since the what is far more specific than "Works with document files".

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/short/sdlc-implementation/skills/test-driven-development/SKILL.md

Reviewed

Table of Contents

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