types: setup tests for built d.ts files

packages/reactivity/src/computed.ts

@@ -2,7 +2,7 @@ import { effect, ReactiveEffect, effectStack } from './effect'
 import { Ref, UnwrapRef } from './ref'
 import { isFunction, NOOP } from '@vue/shared'
 
-export interface ComputedRef<T> extends WritableComputedRef<T> {
+export interface ComputedRef<T = any> extends WritableComputedRef<T> {
   readonly value: UnwrapRef<T>
 }
 

packages/reactivity/src/ref.ts

@@ -15,7 +15,8 @@ const convert = <T extends unknown>(val: T): T =>
 
 export function ref<T extends Ref>(raw: T): T
 export function ref<T>(raw: T): Ref<T>
-export function ref(raw: unknown) {
+export function ref<T = any>(): Ref<T>
+export function ref(raw?: unknown) {
   if (isRef(raw)) {
     return raw
   }