fix: allow localhost as a valid hostname

packages/vite/src/node/__tests__/utils.spec.ts

@@ -1,42 +1,65 @@
-import { getPotentialTsSrcPaths, injectQuery, isWindows } from '../utils'
+import {
+  getPotentialTsSrcPaths,
+  injectQuery,
+  isWindows,
+  resolveHostname
+} from '../utils'
 
-if (isWindows) {
-  // this test will work incorrectly on unix systems
-  test('normalize windows path', () => {
-    expect(injectQuery('C:\\User\\Vite\\Project', 'direct')).toEqual(
-      'C:/User/Vite/Project?direct'
+describe('injectQuery', () => {
+  if (isWindows) {
+    // this test will work incorrectly on unix systems
+    test('normalize windows path', () => {
+      expect(injectQuery('C:\\User\\Vite\\Project', 'direct')).toEqual(
+        'C:/User/Vite/Project?direct'
+      )
+    })
+  }
+
+  test('path with multiple spaces', () => {
+    expect(injectQuery('/usr/vite/path with space', 'direct')).toEqual(
+      '/usr/vite/path with space?direct'
     )
   })
-}
 
-test('path with multiple spaces', () => {
-  expect(injectQuery('/usr/vite/path with space', 'direct')).toEqual(
-    '/usr/vite/path with space?direct'
-  )
-})
+  test('path with multiple % characters', () => {
+    expect(injectQuery('/usr/vite/not%20a%20space', 'direct')).toEqual(
+      '/usr/vite/not%20a%20space?direct'
+    )
+  })
 
-test('path with multiple % characters', () => {
-  expect(injectQuery('/usr/vite/not%20a%20space', 'direct')).toEqual(
-    '/usr/vite/not%20a%20space?direct'
-  )
-})
+  test('path with %25', () => {
+    expect(injectQuery('/usr/vite/%25hello%25', 'direct')).toEqual(
+      '/usr/vite/%25hello%25?direct'
+    )
+  })
 
-test('path with %25', () => {
-  expect(injectQuery('/usr/vite/%25hello%25', 'direct')).toEqual(
-    '/usr/vite/%25hello%25?direct'
-  )
-})
+  test('path with unicode', () => {
+    expect(injectQuery('/usr/vite/東京', 'direct')).toEqual(
+      '/usr/vite/東京?direct'
+    )
+  })
 
-test('path with unicode', () => {
-  expect(injectQuery('/usr/vite/東京', 'direct')).toEqual(
-    '/usr/vite/東京?direct'
-  )
+  test('path with unicode, space, and %', () => {
+    expect(injectQuery('/usr/vite/東京 %20 hello', 'direct')).toEqual(
+      '/usr/vite/東京 %20 hello?direct'
+    )
+  })
 })
 
-test('path with unicode, space, and %', () => {
-  expect(injectQuery('/usr/vite/東京 %20 hello', 'direct')).toEqual(
-    '/usr/vite/東京 %20 hello?direct'
-  )
+describe('resolveHostname', () => {
+  test('defaults to 127.0.0.1', () => {
+    expect(resolveHostname(undefined)).toEqual({
+      host: '127.0.0.1',
+      name: 'localhost'
+    })
+  })
+
+  test('accepts localhost', () => {
+    expect(resolveHostname('localhost')).toEqual({
+      host: 'localhost',
+      name: 'localhost'
+    })
+  })
 })
 
 test('ts import of file with .js extension', () => {

packages/vite/src/node/utils.ts

@@ -638,11 +638,7 @@ export function resolveHostname(
   optionsHost: string | boolean | undefined
 ): Hostname {
   let host: string | undefined
-  if (
-    optionsHost === undefined ||
-    optionsHost === false ||
-    optionsHost === 'localhost'
-  ) {
+  if (optionsHost === undefined || optionsHost === false) {
     // Use a secure default
     host = '127.0.0.1'
   } else if (optionsHost === true) {