feat(Image): add radius prop (#4230)

src/image/test/__snapshots__/index.spec.js.snap

@@ -25,6 +25,13 @@ exports[`load event 2`] = `
 </div>
 `;
 
-exports[`show-loading prop 1`] = `<div class="van-image"><img class="van-image__img"></div>`;
+exports[`radius prop 1`] = `
+<div class="van-image" style="overflow: hidden; border-radius: 3px;"><img src="https://img.yzcdn.cn/vant/cat.jpeg" class="van-image__img">
+  <div class="van-image__loading"><i class="van-icon van-icon-photo-o" style="font-size: 22px;">
+      <!----></i></div>
+</div>
+`;
 
 exports[`show-error prop 1`] = `<div class="van-image"></div>`;
+
+exports[`show-loading prop 1`] = `<div class="van-image"><img class="van-image__img"></div>`;

src/image/test/index.spec.js

@@ -124,3 +124,14 @@ test('show-error prop', () => {
 
   expect(wrapper).toMatchSnapshot();
 });
+
+test('radius prop', () => {
+  const wrapper = mount(Image, {
+    propsData: {
+      radius: 3,
+      src: 'https://img.yzcdn.cn/vant/cat.jpeg'
+    }
+  });
+
+  expect(wrapper).toMatchSnapshot();
+});