Major update for v1 and tests

vitest.config.js

@@ -0,0 +1,73 @@
+import { defineConfig } from 'vitest/config';
+import react from '@vitejs/plugin-react';
+
+// ────────────────────────────────────────────────────────────────────────
+// Vitest configuration.
+//
+// Separate from `vite.config.js` so the production build config stays
+// focused on production concerns (PWA manifest, sticker virtual module,
+// dev-server proxy) and doesn't ship test-only configuration into
+// userland. Vitest reads this file specifically when running tests.
+//
+// What this enables
+// ─────────────────
+//   • jsdom environment — gives tests access to `document`, `window`,
+//     `localStorage`, etc. Required for any test of useDesignEditor
+//     (which reads localStorage for the diagnostic-history flag) and
+//     any future component test using React Testing Library.
+//
+//   • React plugin — JSX compilation. Tests can import .jsx files
+//     directly.
+//
+//   • Setup file — `src/test/setup.js` runs before each test file
+//     and registers @testing-library/jest-dom's custom matchers
+//     (toBeInTheDocument, toHaveTextContent, etc.) plus a global
+//     `afterEach` that cleans up the RTL container so tests don't
+//     bleed state into each other.
+//
+//   • `globals: true` — exposes `describe`/`it`/`expect`/`vi` as
+//     globals so tests don't have to import them from 'vitest'
+//     in every file. This matches Jest's convention (which the
+//     codebase has zero prior tests in but the React community
+//     largely defaults to), and keeps the test files visually
+//     close to the original source they cover.
+//
+// What's NOT here (intentionally)
+// ─────────────────────────────────
+//   • Coverage reporter. We can add `@vitest/coverage-v8` and a
+//     `coverage` config block later if/when we want CI-gated
+//     coverage thresholds. For v1 the tests are themselves the
+//     coverage — adding the reporter now would inflate dev deps
+//     and CI time without yet having a coverage target to enforce.
+//
+//   • Aliases. The codebase uses only relative imports (`'../utils/...'`,
+//     `'./SomeComponent'`); there's no `@/` or similar to teach the
+//     resolver about. If we ever add path aliases to the main vite
+//     config, we'd mirror them here.
+//
+//   • Custom test-include glob. The default `**/*.{test,spec}.{js,jsx}`
+//     matches the co-located convention we're using (test file lives
+//     next to the source it covers). Override only if we add a separate
+//     `tests/` directory later.
+// ────────────────────────────────────────────────────────────────────────
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./src/test/setup.js'],
+    // Co-located tests: `Foo.test.js` next to `Foo.js`.
+    // The default include glob already covers this; listing it
+    // explicitly so the convention is visible in the config file
+    // for anyone exploring the repo.
+    include: ['src/**/*.{test,spec}.{js,jsx}'],
+    // CSS imports in source files (e.g. `import './App.css'`) need to
+    // resolve without errors during test runs even though the styles
+    // themselves don't affect test logic. `css: false` tells Vitest
+    // to short-circuit CSS processing — imports succeed, no parsing
+    // happens, tests stay fast. Set to true (or a finer-grained
+    // matcher) if/when a test needs to assert on computed styles.
+    css: false,
+  },
+});