pad/web/vitest.config.ts

import { defineConfig } from 'vitest/config';
import { fileURLToPath } from 'node:url';
import { createRequire } from 'node:module';
import { realpathSync } from 'node:fs';

// Two-project vitest setup (TASK-2081 / PLAN-1984):
//
//  - `node`  — the existing pure-TS unit suite. Plain node environment, no
//              Svelte plugin (fast; matches the pre-TASK-2081 behavior).
//  - `jsdom` — `.svelte` component + `.svelte.ts` rune-module tests. Runs in a
//              browser-like DOM with the Svelte plugin so runes/components
//              compile, and aliases `$app/environment` to a browser=true mock.
//
// Split by filename: `*.svelte.test.ts` routes to jsdom, everything else
// (`*.test.ts`) stays on node. Keeping the node suite out of jsdom avoids
// slowing/altering the pure-logic tests.
//
// The jsdom project's deps (`jsdom`, `@testing-library/svelte`,
// `@testing-library/jest-dom`) are declared in package.json but may be absent
// until `npm install` runs (worktrees share a read-only node_modules). When
// they're missing we register ONLY the node project, so `npm run test` keeps
// the existing suite green; once installed, the jsdom project activates
// automatically and `npm run test` runs BOTH.

const require = createRequire(import.meta.url);
function canResolve(id: string): boolean {
	try {
		require.resolve(id);
		return true;
	} catch {
		return false;
	}
}

const projectRoot = fileURLToPath(new URL('.', import.meta.url));
const $lib = fileURLToPath(new URL('./src/lib', import.meta.url));
const appEnvironmentMock = fileURLToPath(new URL('./src/test/mocks/app-environment.ts', import.meta.url));
const appStateMock = fileURLToPath(new URL('./src/test/mocks/app-state.ts', import.meta.url));

// Agent worktrees symlink `web/node_modules` to the main checkout's
// node_modules rather than `npm install`-ing a copy (installing clobbers a
// worktree; see CLAUDE.md). Vite's dev-server fs-access guard checks a
// requested file's REALPATH against `server.fs.allow`, which defaults to the
// project root and its ancestors — a node_modules symlink that resolves
// outside that root (the worktree lives under a sibling directory tree) gets
// denied, breaking every jsdom-project test that imports a real package
// (e.g. `@testing-library/svelte/vitest`) with a confusing "does the file
// exist?" error even though it does. Explicitly allowing the resolved
// realpath fixes worktrees without changing behavior for a normal checkout,
// where the realpath is just `<project>/node_modules` — already inside the
// default allow-list. `projectRoot` MUST stay in the allow list alongside
// it — setting `server.fs.allow` REPLACES Vite's default (project root +
// ancestors), so omitting the root here would deny access to ordinary
// project source files (Codex review).
const nodeModulesRealPath = (() => {
	try {
		return realpathSync(fileURLToPath(new URL('./node_modules', import.meta.url)));
	} catch {
		return undefined;
	}
})();

const browserTestDepsInstalled =
	canResolve('jsdom') &&
	canResolve('@testing-library/svelte') &&
	canResolve('@testing-library/jest-dom') &&
	canResolve('@sveltejs/vite-plugin-svelte');

const BROWSER_TEST_GLOB = 'src/**/*.svelte.test.ts';

const nodeProject = {
	resolve: { alias: { $lib } },
	test: {
		name: 'node',
		environment: 'node',
		include: ['src/**/*.test.ts'],
		// The jsdom project owns these; they'd blow up in the plain node env.
		exclude: [BROWSER_TEST_GLOB],
	},
};

export default defineConfig(async () => {
	const projects: Record<string, unknown>[] = [nodeProject];

	if (browserTestDepsInstalled) {
		// Dynamic import so a missing plugin can never crash config loading.
		const { svelte } = await import('@sveltejs/vite-plugin-svelte');
		const { svelteTesting } = await import('@testing-library/svelte/vite');
		projects.push({
			plugins: [svelte(), svelteTesting()],
			resolve: {
				alias: {
					$lib,
					// No SvelteKit plugin in this project, so provide `$app/environment`
					// and `$app/state` — without a provider these don't just come back
					// undefined, they fail to RESOLVE, which is a load-time error for
					// any component that imports them (and one `vi.mock` can't rescue,
					// since resolution happens first).
					'$app/environment': appEnvironmentMock,
					'$app/state': appStateMock,
				},
			},
			server: nodeModulesRealPath
				? { fs: { allow: [projectRoot, nodeModulesRealPath] } }
				: undefined,
			test: {
				name: 'jsdom',
				environment: 'jsdom',
				include: [BROWSER_TEST_GLOB],
				setupFiles: ['./src/test/setup-jsdom.ts'],
			},
		});
	}

	return { test: { projects } };
});