rstest-best-practices

name	rstest-best-practices
description	Rstest best practices for project setup, configuration, CLI workflow, test writing, mocking, snapshot testing, DOM testing, coverage, multi-project setup, and CI integration. Use when setting up, writing, or reviewing Rstest tests and test projects. For systematic startup, build, runtime, logging, memory, or performance diagnosis, use rstest-debugging.

Rstest Best Practices

Apply these rules when setting up, writing, or reviewing Rstest projects.

Workflow

• Inspect the existing package manager, dependency policy, module mode, build configuration, test layout, and framework conventions before editing.
• Add @rstest/core, a package-local test script, and a config file whose extension matches the package's module mode.
• Reuse existing build configuration only when doing so lowers maintenance cost and remains compatible. An adapter is optional; use an independent Rstest config when adapter integration is incompatible or disproportionately costly, and explicitly reproduce required aliases, plugins, defines, environments, and externals.
• Configure test discovery, environment, and setup files intentionally. Do not enable passWithNoTests unless an empty test set is an expected and documented state.
• Verify test discovery with rstest list, then run focused tests, the full suite, and the project's existing build or type-check command.

Configuration and environments

• Use defineConfig from @rstest/core and a config file extension compatible with the package's module mode.
• Prefer explicit imports from @rstest/core over globals: true.
• Use setupFiles for shared matchers and cleanup; use plugins, resolve, or source for ordinary build integration and low-level only when necessary.