docs: Add example using portal-vue (#136)

* Install dep

* Add basic example

Author: afontcu

package-lock.json

@@ -53,6 +53,7 @@
     "jest-serializer-vue": "^2.0.2",
     "kcd-scripts": "^5.4.0",
     "lodash.merge": "^4.6.2",
+    "portal-vue": "^2.1.7",
     "vee-validate": "^2.2.15",
     "vue": "^2.6.11",
     "vue-i18n": "^8.15.5",

package.json

@@ -0,0 +1,30 @@
+import {render, waitFor} from '@testing-library/vue'
+import '@testing-library/jest-dom/extend-expect'
+import PortalVue from 'portal-vue'
+
+const PortalComponent = {
+  template: `
+    <div>
+      <Portal to="portalName" data-testid="portal">
+        <p>Content rendered wherever the portal-target is located.</p>
+      </Portal>
+
+      <PortalTarget name="portalName" data-testid="target" />
+  </div>`,
+}
+
+test('portal', async () => {
+  const {getByTestId} = render(PortalComponent, {}, vue => {
+    vue.use(PortalVue)
+  })
+
+  // wait until PortalVue has removed content from the source element
+  // and moved it to the target one.
+  await waitFor(() => {
+    expect(getByTestId('portal')).toBeEmpty()
+  })
+
+  expect(getByTestId('target')).toHaveTextContent(
+    'Content rendered wherever the portal-target is located.',
+  )
+})