fix(vitest): use correct type for defineProject to allow usage in mer…

…geConfig (#4498)

packages/vitest/src/config.ts

@@ -26,10 +26,10 @@ export function defineConfig(config: UserConfigExport): UserConfigExport {
   return config
 }
 
-export function defineProject(config: UserProjectConfigExport) {
+export function defineProject<T extends UserProjectConfigExport>(config: T): T {
   return config
 }
 
-export function defineWorkspace(config: (string | (UserProjectConfigExport & { extends?: string }))[]) {
+export function defineWorkspace<T extends (string | (UserProjectConfigExport & { extends?: string }))[]>(config: T): T {
   return config
 }

test/config/package.json

@@ -3,7 +3,7 @@
   "type": "module",
   "private": true,
   "scripts": {
-    "test": "vitest run"
+    "test": "vitest run --typecheck"
   },
   "devDependencies": {
     "vite": "latest",

test/config/test/config-types.test-d.ts

@@ -0,0 +1,34 @@
+import { describe, expectTypeOf, test } from 'vitest'
+import { type UserWorkspaceConfig, defineConfig, defineProject, defineWorkspace, mergeConfig } from 'vitest/config'
+
+const expectMainTestConfig = expectTypeOf(defineConfig).parameter(0).resolves.toHaveProperty('test').exclude<undefined>()
+const expectProjectTestConfig = expectTypeOf(defineProject).parameter(0).resolves.toHaveProperty('test').exclude<undefined>()
+
+describe('define project helper', () => {
+  test('cannot define non-project fields on a project config', () => {
+    expectProjectTestConfig.toHaveProperty('name')
+    expectMainTestConfig.toHaveProperty('name')
+
+    expectProjectTestConfig.not.toHaveProperty('pool')
+    expectMainTestConfig.toHaveProperty('pool')
+
+    expectProjectTestConfig.not.toHaveProperty('coverage')
+    expectMainTestConfig.toHaveProperty('coverage')
+  })
+})
+
+describe('merge config helper', () => {
+  test('types are not conflicting', () => {
+    expectTypeOf(mergeConfig(
+      defineConfig({}),
+      defineProject({ test: { name: 'test' } }),
+    )).toMatchTypeOf<Record<string, unknown>>()
+  })
+})
+
+describe('workspace config', () => {
+  test('correctly defines return type', () => {
+    expectTypeOf(defineWorkspace([{ test: { name: 'test' } }])).items.toMatchTypeOf<UserWorkspaceConfig>()
+    expectTypeOf(defineWorkspace(['packages/*'])).items.toBeString()
+  })
+})

test/config/tsconfig.json

@@ -0,0 +1,6 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "exclude": [
+    "**/dist/**"
+  ]
+}