Ensure vite.config.js works on Windows

.changeset/neat-monkeys-dream.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[fix] support vite.config.js on Windows

packages/kit/src/cli.js

@@ -4,8 +4,9 @@ import path from 'path';
 import colors from 'kleur';
 import sade from 'sade';
 import * as vite from 'vite';
-import { load_config } from './core/config/index.js';
 import { networkInterfaces, release } from 'os';
+import { pathToFileURL } from 'url';
+import { load_config } from './core/config/index.js';
 import { coalesce_to_error } from './utils/error.js';
 
 /** @param {unknown} e */
@@ -289,7 +290,7 @@ export async function get_vite_config(svelte_config) {
 	for (const file of ['vite.config.js', 'vite.config.mjs', 'vite.config.cjs']) {
 		if (fs.existsSync(file)) {
 			// TODO warn here if config.kit.vite was specified
-			const module = await import(path.resolve(file));
+			const module = await import(pathToFileURL(file).toString());
 			return {
 				...module.default,
 				configFile: false

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

@@ -1,5 +1,3 @@
-import * as path from 'path';
-
 /** @type {import('@sveltejs/kit').Config} */
 const config = {
 	kit: {
@@ -8,16 +6,6 @@ const config = {
 		},
 		serviceWorker: {
 			register: false
-		},
-		vite: {
-			server: {
-				// TODO: required to support ipv6, remove on vite 3
-				// https://github.com/vitejs/vite/issues/7075
-				host: 'localhost',
-				fs: {
-					allow: [path.resolve('../../../src')]
-				}
-			}
 		}
 	}
 };

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

@@ -0,0 +1,17 @@
+import * as path from 'path';
+import { sveltekit } from '@sveltejs/kit/experimental/vite';
+
+/** @type {import('vite').UserConfig} */
+const config = {
+	plugins: [sveltekit()],
+	server: {
+		// TODO: required to support ipv6, remove on vite 3
+		// https://github.com/vitejs/vite/issues/7075
+		host: 'localhost',
+		fs: {
+			allow: [path.resolve('../../../src')]
+		}
+	}
+};
+
+export default config;