test(reactivity): declare the exact type (#644)

packages/reactivity/__tests__/ref.spec.ts

@@ -42,7 +42,7 @@ describe('reactivity/ref', () => {
         d: [a]
       }
     })
- 
+
     let dummy1: number
     let dummy2: number
     let dummy3: number
@@ -53,7 +53,7 @@ describe('reactivity/ref', () => {
       dummy3 = obj.b.d[0]
     })
 
-    const assertDummiesEqualTo = (val: any) =>
+    const assertDummiesEqualTo = (val: number) =>
       [dummy1, dummy2, dummy3].forEach(dummy => expect(dummy).toBe(val))
 
     assertDummiesEqualTo(1)