Zucchini Rules for VS Code

Explore your Zucchini business rules, see which scenarios cover them, and run those scenarios without leaving your editor. When coverage is missing, ask AI to draft examples or look for counterexamples.

• Find coverage gaps. Browse rules and their obligations to see what still needs an example.
• Read scenarios in context. Jump to a scenario and hover over highlighted steps to see the rules they exercise.
• Run what matters. Run one scenario, a rule’s scenarios, or a whole fixture, and see the results in the sidebar.
• Draft more scenarios. Generate passing examples or counterexamples using a language model available in VS Code.

Get started

1. Install Zucchini Rules from the VS Code Extensions Marketplace.
2. Open your Zucchini project. Enable RULE_COVERAGE_REPORT in your project’s zucchinify() call and build it to generate the rule reports.
3. Click the Zucchini icon in the Activity Bar to explore your rules.

Requires VS Code 1.95 or newer. To run scenarios, CTest must be available on your PATH, or configured in the extension’s settings. Build your project with your usual tools; the view updates when reports change.

For help setting up reports, see the rules setup guide.

Explore your rules

Expand a fixture to see its rules, then expand a rule to see its obligations and the scenarios that exercise them. Warning icons flag obligations without coverage. Use Show Flat Scenarios in the view toolbar to list scenarios directly under each fixture. The same button becomes Show Rule Hierarchy to switch back; the view description shows the current mode.

Use the funnel button in the view toolbar to open VS Code's native Find field inside the tree. Its filter toggle switches between highlighting matches and hiding nonmatching rows. The funnel expands and loads branches first so the native filter can evaluate the nested hierarchy. This is a tree label search, not the fixture-pattern filter. Press Escape to close the field. For persistent fixture-name patterns, use Zucchini: Fixture Filter in Settings (for example Shop*, Inventory, !Legacy*).

Click a scenario to open its feature file. While the Zucchini view is visible, steps with rule observations are highlighted. Hover over them for details.

Coverage tells you that a scenario exercised an obligation during discovery. Run the scenario to check whether it passes.

Run scenarios

Click the play button beside a scenario, obligation, rule, or fixture. Results appear in the sidebar; detailed output is available in the Zucchini output channel. Starting a run, AI action, or manual refresh clears the previous output. The view also picks up results from runs outside the extension.

After you edit a scenario, save and rebuild your project before running it here. New scenarios appear as Awaiting discovery until then. Older results are marked stale when they no longer match the current scenarios.

Generate scenarios with AI

Click the sparkle button beside a rule or obligation and choose:

• Generate Passing Examples to demonstrate the expected behavior.
• Generate Failing Counterexamples to look for cases where the implementation breaks the rule.

Choose a model when prompted. You’ll need a language model provider in VS Code that supports extension requests, such as GitHub Copilot Chat. Authentication and any charges are handled by your provider.

Generation sends the selected rule, feature files, step definitions, and relevant implementation source to your chosen provider, including unsaved editor content. This context helps the model use your existing steps and understand the behavior it should test.

Drafts are added to feature files as unsaved editor changes. Review them, save, and rebuild to discover and validate the new scenarios. The model may explain that it cannot find a suitable example or counterexample. Generated scenarios can still be wrong, so review their assertions and step usage.

Progress and completion appear as notifications. The model’s explanation is available in the Zucchini output channel. Running scenarios and generating with AI require a trusted workspace.

Settings and help

Search for Zucchini in VS Code Settings to change the scenario count, report locations, grouping, or CTest path. Most projects can use the defaults.

• No rules appear? Build your project with rule coverage reports enabled, then run Zucchini: Refresh Reports. If reports are in a custom location, update Zucchini: Report Patterns.
• A report is incompatible? Update the extension or rebuild with a compatible Zucchini version.
• Generation cannot find your sources? Set the fixture’s manifest or sourceFiles in Zucchini: Fixtures.
• No usable AI model appears? Enable GitHub Copilot Chat or another provider that supports extension requests. Copilot CLI chat-session models cannot be used for scenario generation.

See the configuration and development guide for advanced settings and contributor instructions. Report problems on GitHub.