tests-vitestlisted

# Frontend unit tests: Vitest Write and run frontend component and unit tests using Vitest conventions. The unit-test script is the project's own (`test`/`test:unit`) or `npx vitest run`. - Test files are typically co-located with their source file (`Button.test.tsx` next to `Button.tsx`) or collected under `src/__tests__/`. Check the project's `vitest.config.ts` (or `.js`/`.mjs`) for the actual `include` pattern before creating a new file. - Use `@testing-library/react` (`render`, `screen`) with `userEvent` from `@testing-library/user-event` for component tests; use plain `vi.fn()` / `vi.spyOn()` for unit mocks and `vi.mock()` for module mocks. - Prefer queries that reflect how users perceive the UI (`getByRole`, `getByLabelText`, `getByText`) over implementation-detail selectors (`getByTestId`, CSS class). - **Targeted rerun:** the test file path and/or `-t`/`--testNamePattern`. `--reporter` only changes output format; it does not filter which tests run. - **Discovery:** `npx vitest list <file>` prints the test cases without running them. An empty list means the `include` pattern misses the file. - **Skip mechanism:** `it.skip`/`describe.skip`.