types: test cases typing

src/slider/test/index.spec.ts

@@ -141,7 +141,7 @@ test('should change slider bar height when using bar-height prop', () => {
     },
   });
 
-  expect(wrapper.element.style.height).toEqual('10px');
+  expect(wrapper.style.height).toEqual('10px');
 });
 
 test('shoud change button size when using button-size prop', () => {
@@ -152,7 +152,7 @@ test('shoud change button size when using button-size prop', () => {
     },
   });
 
-  const button = wrapper.find('.van-slider__button').element;
+  const button = wrapper.find('.van-slider__button');
   expect(button.style.width).toEqual('10px');
   expect(button.style.height).toEqual('10px');
 });