respect env.dir when running preview (#7001)

* respect env.dir when running preview - closes #6204

* add test

Author: Rich-Harris

.changeset/forty-news-smell.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Respect `config.kit.env.dir` when running `vite preview`

packages/kit/src/exports/vite/preview/index.js

@@ -46,7 +46,7 @@ export async function preview(vite, vite_config, svelte_config) {
 
 	const server = new Server(manifest);
 	await server.init({
-		env: loadEnv(vite_config.mode, process.cwd(), '')
+		env: loadEnv(vite_config.mode, svelte_config.kit.env.dir, '')
 	});
 
 	return () => {

packages/kit/test/apps/options-2/src/routes/env/+page.svelte

@@ -1,5 +1,7 @@
 <script>
 	import { PUBLIC_LOOK_IN_OPTIONS_2 } from '$env/static/public';
+	import { env } from '$env/dynamic/public';
 </script>
 
-<p>{PUBLIC_LOOK_IN_OPTIONS_2}</p>
+<p data-testid="static">static: {PUBLIC_LOOK_IN_OPTIONS_2}</p>
+<p data-testid="dynamic">dynamic: {env.PUBLIC_LOOK_IN_OPTIONS_2}</p>

packages/kit/test/apps/options-2/test/test.js

@@ -8,7 +8,8 @@ test.describe.configure({ mode: 'parallel' });
 test.describe('env', () => {
 	test('resolves upwards', async ({ page }) => {
 		await page.goto('/basepath/env');
-		expect(await page.textContent('p')).toBe('resolves upwards!');
+		expect(await page.textContent('[data-testid="static"]')).toBe('static: resolves upwards!');
+		expect(await page.textContent('[data-testid="dynamic"]')).toBe('dynamic: resolves upwards!');
 	});
 });