fix(css): don't mock css-module if inline is specified (#3952)

Co-authored-by: Adam Hines <ahines@factset.com>

packages/vitest/src/node/plugins/cssEnabler.ts

@@ -7,6 +7,7 @@ import { toArray } from '../../utils'
 const cssLangs = '\\.(css|less|sass|scss|styl|stylus|pcss|postcss)($|\\?)'
 const cssLangRE = new RegExp(cssLangs)
 const cssModuleRE = new RegExp(`\\.module${cssLangs}`)
+const cssInlineRE = /[?&]inline(&|$)/
 
 function isCSS(id: string) {
   return cssLangRE.test(id)
@@ -16,6 +17,12 @@ function isCSSModule(id: string) {
   return cssModuleRE.test(id)
 }
 
+// inline css requests are expected to just return the
+// string content directly and not the proxy module
+function isInline(id: string) {
+  return cssInlineRE.test(id)
+}
+
 function getCSSModuleProxyReturn(strategy: CSSModuleScopeStrategy, filename: string) {
   if (strategy === 'non-scoped')
     return 'style'
@@ -55,7 +62,7 @@ export function CSSEnablerPlugin(ctx: { config: ResolvedConfig }): VitePlugin[]
         if (!isCSS(id) || shouldProcessCSS(id))
           return
 
-        if (isCSSModule(id)) {
+        if (isCSSModule(id) && !isInline(id)) {
           // return proxy for css modules, so that imported module has names:
           // styles.foo returns a "foo" instead of "undefined"
           // we don't use code content to generate hash for "scoped", because it's empty

test/css/test/process-inline.spec.ts

@@ -0,0 +1,20 @@
+import { describe, expect, test } from 'vitest'
+import { useRemoveStyles } from './utils'
+
+describe('processing inline css', () => {
+  useRemoveStyles()
+
+  test('doesn\'t apply css', async () => {
+    await import('../src/App.module.css?inline')
+
+    const element = document.createElement('div')
+    element.className = 'main'
+    const computed = window.getComputedStyle(element)
+    expect(computed.display, 'css is not processed').toBe('block')
+  })
+
+  test('returns a string', async () => {
+    const { default: style } = await import('../src/App.module.css?inline')
+    expect(typeof style).toBe('string')
+  })
+})

test/css/testing.mjs

@@ -3,14 +3,15 @@ import { startVitest } from 'vitest/node'
 const configs = [
   ['test/default-css', {}],
   ['test/process-css', { include: [/App\.css/] }],
-  ['test/process-module', { include: [/App\.module\.css/] }],
+  [['test/process-module', 'test/process-inline'], { include: [/App\.module\.css/] }],
   ['test/scope-module', { include: [/App\.module\.css/], modules: { classNameStrategy: 'scoped' } }],
   ['test/non-scope-module', { include: [/App\.module\.css/], modules: { classNameStrategy: 'non-scoped' } }],
 ]
 
 async function runTests() {
   for (const [name, config] of configs) {
-    await startVitest('test', [name], {
+    const names = Array.isArray(name) ? name : [name];
+    await startVitest('test', names, {
       run: true,
       css: config,
       update: false,