fix(vitest): improve defineProject and defineWorkspace types (#6198)

Author: sheremet-va

docs/guide/workspace.md

@@ -96,6 +96,7 @@ Workspace projects don't support all configuration properties. For better type s
 
 :::code-group
 ```ts [packages/a/vitest.config.ts] twoslash
+// @errors: 2769
 import { defineProject } from 'vitest/config'
 
 export default defineProject({

netlify.toml

@@ -1,7 +1,7 @@
 [build]
 publish = "docs/.vitepress/dist"
 command = "pnpm ci:docs"
-ignore = "git diff --quiet $COMMIT_REF $CACHED_COMMIT_REF -- docs/ package.json pnpm-lock.yaml"
+ignore = "git diff --quiet $CACHED_COMMIT_REF $COMMIT_REF docs/ package.json pnpm-lock.yaml"
 
 [build.environment]
 NODE_VERSION = "20"

packages/vitest/src/config.ts

@@ -48,12 +48,22 @@ export function defineConfig(config: UserConfigExport): UserConfigExport {
   return config
 }
 
-export function defineProject<T extends UserProjectConfigExport>(config: T): T {
+export function defineProject(config: UserWorkspaceConfig): UserWorkspaceConfig
+export function defineProject(config: Promise<UserWorkspaceConfig>): Promise<UserWorkspaceConfig>
+export function defineProject(config: UserProjectConfigFn): UserProjectConfigFn
+export function defineProject(config: UserProjectConfigExport): UserProjectConfigExport
+export function defineProject(config: UserProjectConfigExport): UserProjectConfigExport {
   return config
 }
 
-type Workspace = string | (UserProjectConfigExport & { extends?: string })
+type WorkspaceProjectConfiguration = string | (UserProjectConfigExport & {
+  /**
+   * Relative path to the extendable config. All other options will be merged with this config.
+   * @example '../vite.config.ts'
+   */
+  extends?: string
+})
 
-export function defineWorkspace(config: Workspace[]): Workspace[] {
+export function defineWorkspace(config: WorkspaceProjectConfiguration[]): WorkspaceProjectConfiguration[] {
   return config
 }