test(breadcrumb): improve test coverage

Author: aioya

packages/varlet-ui/src/breadcrumb/__tests__/index.spec.js

@@ -0,0 +1,13 @@
+import { expect, test } from 'vite-plus/test'
+import { createApp } from 'vue'
+import Breadcrumb, { _BreadcrumbComponent, breadcrumbProps } from '..'
+
+test('breadcrumb plugin', () => {
+  const app = createApp({}).use(Breadcrumb)
+  expect(app.component(Breadcrumb.name)).toBeTruthy()
+})
+
+test('breadcrumb exports', () => {
+  expect(_BreadcrumbComponent).toBeTruthy()
+  expect(breadcrumbProps).toBeTruthy()
+})