Canonical Copilot Collections is a repository for organizing and distributing GitHub Copilot instructions, prompts, agents, and skills across Canonical repositories. Teams configure repositories to subscribe to shared collections, such as Python, documentation, or Juju development guidance, and keep those assets synchronized.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add canonical/copilot-collections --skill migrate-harness-tests-to-state-transition-testgit clone --depth 1 https://github.com/canonical/copilot-collectionsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/canonical/copilot-collections/migrate-harness-tests-to-state-transition-test)<a href="https://agentmods.dev/skills/canonical/copilot-collections/migrate-harness-tests-to-state-transition-test"><img src="https://agentmods.dev/badge/skills/canonical/copilot-collections/migrate-harness-tests-to-state-transition-test/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/canonical/copilot-collections/migrate-harness-tests-to-state-transition-test"><img src="https://agentmods.dev/badge/skills/canonical/copilot-collections/migrate-harness-tests-to-state-transition-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00049 | $0.01586 |
| Opus 5 | $0.00024 | $0.00793 |
| Sonnet 5 | $0.00010 | $0.00317 |
| Haiku 4.5 | $0.00005 | $0.00159 |
Grade A, and why
migrate-harness-tests-to-state-transition-test scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Migrate Harness Tests To State Transition Test
Overview
Guide charm maintainers through replacing deprecated Harness-based unit tests with deterministic state-transition tests that mirror how Juju actually fires events. Use this skill whenever a test still instantiates testing.Harness or chains multiple events inside one fixture.
When To Use
ops.testing.Harness(or Scenario Harness helpers) still appear in tests or fixtures.- Migration requires modeling relations, containers, secrets, or actions with
testing.State. - CI must stay green while Harness-only helpers (
add_relation,evaluate_status, etc.) are removed.
Preflight Checks
- Inspect
pyproject.toml(or requirements files) before touching code; ensureops[testing]is present in every dependency group that executes Scenario/state-transition tests. Remove legacyops-scenarioif it lingers. - Match the repo’s package manager: use
uv add --group unit ops[testing](and mirror across groups) when[tool.uv]oruv.lockexists; otherwise edit the appropriaterequirements.txt, Poetry group, etc. - After dependency edits, re-sync the exact groups you touched (
uv sync --group unit --group lint,poetry install, etc.) so the virtualenv contains Scenario Context. - Re-run the project’s bootstrap entrypoint (
uv sync,pip install -r requirements.txt,make setup, …) to align local + CI execution before rewriting tests.
Mandatory Plan & Ledger
Create a written task list before editing files and keep it updated:
- Record the migration goal (e.g., "Drop Harness from tests/unit/test_charm.py") plus all files involved.
- Add explicit tasks for every preflight requirement: dependency inspection, disposable venv creation, environment sync commands, bootstrap targets.
- Inventory Harness usage with the detector script, note each file’s assertions, and migrate files one by one in ledger order.
- Pair every code-change task with an immediate verification task (targeted pytest/tox command). Log the command, exit code, and timestamp when marking done.
- If a command fails, append remediation + re-run tasks; do not advance to the next file until the paired verification succeeds.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 86 lines · 49 tokens per session scan A 0222b035fa4f
migrate-harness-tests-to-state-transition-test is a skill published in the GitHub repository canonical/copilot-collections (29 stars, last pushed 9d ago), licensed Apache-2.0. It adds 49 tokens to every session and 1,586 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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