test(reactivity): replace isReactive with isReadonly (#7513)

packages/reactivity/__tests__/readonly.spec.ts

@@ -450,7 +450,7 @@ describe('reactivity/readonly', () => {
       bar: markRaw({ b: 2 }),
     })
     expect(isReadonly(obj.foo)).toBe(true)
-    expect(isReactive(obj.bar)).toBe(false)
+    expect(isReadonly(obj.bar)).toBe(false)
   })
 
   test('should make ref readonly', () => {