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Agent skill

Principle Test Behavior Not Implementation

by chmonitor in chmonitor/chmonitor

Apply when you write, change, or keep a test. An agent skill from chmonitor/chmonitor.

GPL-3.0Auto-check passed

Install Principle Test Behavior Not Implementation

skills CLI
$ npx skills add chmonitor/chmonitor --skill principle-test-behavior-not-implementation -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install chmonitor/chmonitor principle-test-behavior-not-implementation --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/chmonitor/chmonitor.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/pstack/upstream/skills/principle-test-behavior-not-implementation .claude/skills/principle-test-behavior-not-implementation && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
principle-test-behavior-not-implementation
GitHub stars
298
Used in
1 other repo
Token cost
~526 tokens
SKILL.md length
274 words
Files
1
Skills in repo
53
Repo updated
First seen
Licence
GPL-3.0

At a glance

Apply when you write, change, or keep a test. An agent skill from chmonitor/chmonitor.

  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Principle Test Behavior Not Implementation is an agent skill from chmonitor/chmonitor. Apply when you write, change, or keep a test. Identify a relevant defect and check that the test detects it. Assert the required result or observable effect, including absence when the contract requires it.

Its SKILL.md is about 530 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

The repository describes itself as: Open-source operational advisor for ClickHouse — real-time monitoring plus AI-driven index/partition/materialized-view recommendations. The licence is GPL-3.0.

Example prompts

  • “/principle-test-behavior-not-implementation”

What it can do on your machine

Read from SKILL.md and the folder at commit fc39ef0. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Principle Test Behavior Not Implementation loads about 526 tokens when it runs. Until then it costs about 62 tokens; SKILL.md has 274 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~62
When it runs · the whole SKILL.md, loaded when a task matches
~526

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from chmonitor/chmonitor at commit fc39ef0, republished under its GPL-3.0 licence (© chmonitor). 274 words, ~526 tokens.

Download SKILL.mdSave it as .claude/skills/principle-test-behavior-not-implementation/SKILL.md (or your agent's skills folder).
name
principle-test-behavior-not-implementation
description
Apply when you write, change, or keep a test. Identify a relevant defect and check that the test detects it. Assert the required result or observable effect, including absence when the contract requires it.
user-invocable
false

Test behavior, not implementation

Before keeping a test, name a relevant defect and determine whether the complete test arrangement detects it. Where practical, introduce that defect temporarily and observe the failure. Exercise the subject through its public interface and check the required result or effect.

  • A missing-result experiment helps when the contract requires a result. toBeDefined detects a missing result, but accepts the wrong one. Strengthen it to check the particular result when correctness requires one.
  • Keep absence assertions when absence is required. For a denied operation that must send no email, exercise the denial and check the outbox is empty. Temporarily make the denied path send an email and confirm the test fails. An assertion on absence does not require a positive case in the same test.
  • Keep fixed-value checks when the value is an explicit user-facing contract, such as a promised default or instruction. Name that contract and the defect a changed value would cause. Avoid freezing incidental constants or prompt wording with no such contract.
  • Keep comparisons between results when disagreement exposes a real defect. An expected result computed through the same faulty path as the actual result can confirm itself. Use an independent expectation or a relation that the identified defect actually violates.
  • Assess shared setup and the test body together. Calling the subject in beforeEach is valid; asserting only untouched fixture data is not.

Reject tests that exercise nothing relevant, assert nothing meaningful, or only show that a substitute was called without checking the required effect. Check its payload or resulting state when that establishes the contract. An assertion's syntax alone cannot tell you whether it detects a defect.

© chmonitor, GPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .claude/skills/pstack/upstream/skills/principle-test-behavior-not-implementation of chmonitor/chmonitor.

Open the folder on GitHubat commit fc39ef0

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in chmonitor/chmonitor, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Principle Test Behavior Not Implementation next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Principle Test Behavior Not Implementation compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Principle Test Behavior Not Implementation this skillchmonitor/chmonitor2981 repos~526Automated safety check: PassGPL-3.0
Principle Redesign From First Principlescursor/plugins10k8 repos~211Automated safety check: PassNone
Uxui Principlessickn33/agentic-awesome-skills47k2 repos~548Automated safety check: PassMIT
First Principles Thinkingmindfold-ai/Trellis15k—~4.1kAutomated safety check: PassMIT
Keep Trackdavidondrej/skills4.1k—~132Automated safety check: PassMIT
Editorial Burgundy Principles Templatenexu-io/open-design100k—~461Automated safety check: PassApache-2.0

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Questions about Principle Test Behavior Not Implementation

What does Principle Test Behavior Not Implementation do?

Apply when you write, change, or keep a test. An agent skill from chmonitor/chmonitor. Principle Test Behavior Not Implementation is an agent skill from chmonitor/chmonitor. Apply when you write, change, or keep a test.

How do I install Principle Test Behavior Not Implementation in Claude Code?

Run `npx skills add chmonitor/chmonitor --skill principle-test-behavior-not-implementation -a claude-code`. Or copy the skill folder (.claude/skills/pstack/upstream/skills/principle-test-behavior-not-implementation in chmonitor/chmonitor) into .claude/skills/principle-test-behavior-not-implementation in your project. Claude Code loads it when a task matches its description.

How do I install Principle Test Behavior Not Implementation in Codex?

Run `npx skills add chmonitor/chmonitor --skill principle-test-behavior-not-implementation -a codex`. Or copy the skill folder (.claude/skills/pstack/upstream/skills/principle-test-behavior-not-implementation in chmonitor/chmonitor) into .agents/skills/principle-test-behavior-not-implementation in your project. Codex loads it when a task matches its description.

Can I use Principle Test Behavior Not Implementation in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add chmonitor/chmonitor --skill principle-test-behavior-not-implementation -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/principle-test-behavior-not-implementation, .gemini/skills/principle-test-behavior-not-implementation, .github/skills/principle-test-behavior-not-implementation and .opencode/skills/principle-test-behavior-not-implementation in your project.

What does Principle Test Behavior Not Implementation need to run?

SKILL.md names no scripts, command-line tools or credentials: Principle Test Behavior Not Implementation is instructions for the agent only.

Does Principle Test Behavior Not Implementation access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Principle Test Behavior Not Implementation safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Principle Test Behavior Not Implementation use?

Principle Test Behavior Not Implementation is published under the GPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Principle Test Behavior Not Implementation use?

About 526 tokens (SKILL.md is roughly 2.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Principle Test Behavior Not Implementation?

Skills that share tags, products or a category with Principle Test Behavior Not Implementation: Principle Redesign From First Principles (cursor/plugins, 10k stars), Uxui Principles (sickn33/agentic-awesome-skills, 47k stars), First Principles Thinking (mindfold-ai/Trellis, 15k stars) and Keep Track (davidondrej/skills, 4.1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Principle Test Behavior Not Implementation?

chmonitor (a GitHub organization) maintains it in chmonitor/chmonitor, which has 298 GitHub stars. The repository holds 53 skills in this directory. The repository was last updated on October 5, 2026.

Source: chmonitor/chmonitor on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.