tests

frontend/vite.config.ts

@@ -1,7 +1,23 @@
 import { sveltekit } from '@sveltejs/kit/vite';
 import tailwindcss from '@tailwindcss/vite';
-import { defineConfig } from 'vite';
+import { fileURLToPath } from 'node:url';
+import { defineConfig } from 'vitest/config';
 
-export default defineConfig({
-  plugins: [tailwindcss(), sveltekit()]
-});
+export default defineConfig(({ mode }) => ({
+  plugins: [tailwindcss(), sveltekit()],
+  // Under Vitest, resolve Svelte's browser (client) build so components can
+  // `mount` in jsdom instead of hitting the SSR build.
+  resolve: mode === 'test' ? { conditions: ['browser'] } : {},
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./vitest-setup.ts'],
+    include: ['src/**/*.{test,spec}.{js,ts}'],
+    alias: {
+      // SvelteKit's $env virtual module isn't available outside the dev server.
+      '$env/dynamic/public': fileURLToPath(
+        new URL('./src/test-mocks/env-dynamic-public.ts', import.meta.url)
+      )
+    }
+  }
+}));