scenario-tests

Drive Juju charm state transitions with ops.testing Scenario for unit tests.

1|Updated Feb 8, 2026

Search Tags:#testing #charm #scenario #unit-testing #juju #ops.testing

Ready to run

npx skills add https://github.com/tonyandrewmeyer/cantrip --skill scenario-tests

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: scenario-tests
Source: https://github.com/tonyandrewmeyer/cantrip/tree/main/src/cantrip/skills/scenario-tests
Command: npx skills add https://github.com/tonyandrewmeyer/cantrip --skill scenario-tests

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Authoring unit tests for Juju charms can be error-prone and time-consuming without a structured testing framework.

Core Features & Use Cases

State-transition tests using ops.testing Scenario to drive charm behavior.
Clear separation of Context, State, and events for deterministic testing.
Guidance for testing common flows such as start, relation_joined, config_changed, and pebble_ready in isolation.

Quick Start

Create tests under tests/unit and use Scenario's Context, State, and on.* events to drive state transitions.

Frequently Asked Questions about scenario-tests

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I write unit tests for Juju charms without deploying to a live environment?▼

Scenario testing separates Context, State, and events to validate charm behavior across events like start, relation_joined, config_changed, and pebble_ready. This structured approach prevents errors and saves time when authoring unit tests for Juju charms.

What is the best way to test Pebble interactions in a Juju charm?▼

The best way to test Pebble interactions is using Scenario with ops.testing to drive state transitions. This allows you to validate pebble_ready events and Pebble behavior deterministically without a live Juju deployment.

Can I use pytest with ops.testing to verify Juju charm events?▼

Using pytest with ops.testing and Scenario allows you to verify Juju charm events by driving state transitions. This validates unit behavior across events such as start, relation_joined, and update_status without a live deployment.

How do I test config_changed and relation_joined events in isolation for my charm?▼

To test config_changed and relation_joined events in isolation, use Scenario with ops.testing to drive state transitions. This allows deterministic validation of charm unit behavior across these events without a live environment.

Does Scenario testing require a live Juju environment to validate charm behavior?▼

Scenario enables reliable Juju charm unit testing without a live deployment. By driving state transitions with ops.testing, it validates unit behavior across events such as start, config_changed, and update_status.

Why should I use Scenario for charm unit testing instead of manual testing approaches?▼

Using Scenario for charm unit testing avoids the error-prone nature of manual approaches. It provides clear separation of Context, State, and events, driving state transitions with ops.testing to validate behavior deterministically.