test: add test case

packages/runtime-core/__tests__/hmr.spec.ts

@@ -14,6 +14,7 @@ import {
 import * as runtimeTest from '@vue/runtime-test'
 import { createApp, registerRuntimeCompiler } from '@vue/runtime-test'
 import { baseCompile } from '@vue/compiler-core'
+import { createSSRApp } from '@vue/runtime-dom'
 
 declare var __VUE_HMR_RUNTIME__: HMRRuntime
 const { createRecord, rerender, reload } = __VUE_HMR_RUNTIME__
@@ -894,4 +895,41 @@ describe('hot module replacement', () => {
     await timeout()
     expect(serializeInner(root)).toBe('<div>bar</div>')
   })
+
+  /**
+   * @vitest-environment jsdom
+   */
+  test('reload child wrapped in KeepAlive', async () => {
+    const id = 'child-reload'
+    const Child: ComponentOptions = {
+      __hmrId: id,
+      render: compileToFunction(`<div>foo</div>`),
+    }
+    createRecord(id, Child)
+
+    const appId = 'test-app-id'
+    const App: ComponentOptions = {
+      __hmrId: appId,
+      components: { Child },
+      render: compileToFunction(`
+        <div>
+        <KeepAlive>
+          <Child />
+        </KeepAlive>
+      </div>
+      `),
+    }
+
+    const root = document.createElement('div')
+    root.innerHTML = runtimeTest.renderToString(h(App))
+    createSSRApp(App).mount(root)
+    expect(root.innerHTML).toBe('<div><div>foo</div></div>')
+
+    reload(id, {
+      __hmrId: id,
+      render: compileToFunction(`<div>bar</div>`),
+    })
+    await timeout()
+    expect(root.innerHTML).toBe('<div><div>bar</div></div>')
+  })
 })