vite: allow passing overrides for vite config

Author: XiNiHa

.changeset/modern-schools-tan.md

@@ -0,0 +1,5 @@
+---
+'@vanilla-extract/vite-plugin': minor
+---
+
+Add `viteConfigOverrides` option

packages/vite-plugin/package.json

@@ -16,7 +16,8 @@
   "author": "SEEK",
   "license": "MIT",
   "dependencies": {
-    "@vanilla-extract/integration": "workspace:^"
+    "@vanilla-extract/integration": "workspace:^",
+    "deepmerge": "^4.3.1"
   },
   "devDependencies": {
     "vite": "^5.0.11"

packages/vite-plugin/src/index.ts

@@ -18,6 +18,7 @@ import {
   createCompiler,
   normalizePath,
 } from '@vanilla-extract/integration';
+import deepmerge from 'deepmerge';
 
 const virtualExtCss = '.vanilla.css';
 
@@ -45,10 +46,12 @@ const removeIncompatiblePlugins = (plugin: PluginOption) =>
 interface Options {
   identifiers?: IdentifierOption;
   unstable_mode?: 'transform' | 'emitCss';
+  viteConfigOverrides?: Partial<UserConfig>;
 }
 export function vanillaExtractPlugin({
   identifiers,
   unstable_mode: mode = 'emitCss',
+  viteConfigOverrides = {},
 }: Options = {}): Plugin {
   let config: ResolvedConfig;
   let configEnv: ConfigEnv;
@@ -142,12 +145,15 @@ export function vanillaExtractPlugin({
           configForViteCompiler = config.inlineConfig;
         }
 
-        const viteConfig = {
-          ...configForViteCompiler,
-          plugins: configForViteCompiler?.plugins
-            ?.flat()
-            .filter(removeIncompatiblePlugins),
-        };
+        const viteConfig = deepmerge(
+          {
+            ...configForViteCompiler,
+            plugins: configForViteCompiler?.plugins
+              ?.flat()
+              .filter(removeIncompatiblePlugins),
+          },
+          viteConfigOverrides,
+        );
 
         compiler = createCompiler({
           root: config.root,