image-gen-mcp: Skill for Claude Code

Rstest Best Practices

Apply these rules when writing or reviewing Rstest test projects.

Configuration

• Use rstest.config.ts and defineConfig from @rstest/core
• Prefer explicit imports import { test, expect, describe } from '@rstest/core' over globals: true
• For Rsbuild projects, use @rstest/adapter-rsbuild with extends: withRsbuildConfig() to reuse build config
• For Rslib projects, use @rstest/adapter-rslib with extends: withRslibConfig() to reuse build config
• Use setupFiles for shared test setup (e.g., custom matchers, cleanup hooks)
• When using Rsbuild plugins (e.g., @rsbuild/plugin-react), add them via the plugins field
• For deep-level or advanced build configuration needs, use tools.rspack or tools.bundlerChain

CLI

• Use rstest or rstest run to run tests (run disables watch mode, suitable for CI)
• Use rstest --watch or rstest watch for local development with file watching
• Use rstest list to list all test files and test names
• Use rstest -u to update snapshots
• Use --reporter=verbose when debugging test failures for detailed output
• Use --config (-c) to specify a custom config file path

Test writing

• Import test APIs from @rstest/core: test, describe, expect, beforeEach, afterEach, etc.
• Use test or it for test cases; use describe for grouping related tests
• Use .only to focus on specific tests during development, but never commit .only to the codebase
• Use .skip or .todo to mark incomplete or temporarily skipped tests
• Prefer small, focused test cases that test a single behavior
• For async error paths, prefer await expect(fn()).rejects.toThrow(ErrorClass) (or .rejects.toMatchObject({ ... })) over try/catch with expect.fail or .catch(e => e) patterns — the matcher form fails clearly if the promise unexpectedly resolves, keeps the assertion in one chain, and avoids forgetting to assert the throw at all
• For async happy paths, use await expect(fn()).resolves.toEqual(...) for the same reason
• Use includeSource for in-source testing of small utility functions (Rust-style import.meta.rstest)
• For in-source tests, wrap test code in if (import.meta.rstest) { ... } and define import.meta.rstest as false in production build config