feat: serialize for test renderer

packages/renderer-test/src/index.ts

@@ -10,5 +10,6 @@ const { render: _render } = createRenderer({
 type publicRender = (node: VNode | null, container: TestElement) => void
 export const render = _render as publicRender
 
+export { serialize } from './serialize'
 export * from './nodeOps'
 export * from '@vue/core'

packages/renderer-test/src/serialize.ts

@@ -0,0 +1,30 @@
+import { TestElement, TestNode, NodeTypes, TestText } from './nodeOps'
+
+export function serialize(node: TestNode, depth: number = 0): string {
+  if (node.type === NodeTypes.ELEMENT) {
+    return serializeElement(node, depth)
+  } else {
+    return serializeText(node, depth)
+  }
+}
+
+function serializeElement(node: TestElement, depth: number): string {
+  const props = Object.keys(node.props)
+    .map(key => {
+      return `${key}=${JSON.stringify(node.props[key])}`
+    })
+    .join(' ')
+  const children = node.children.length
+    ? `\n${node.children.map(c => serialize(c, depth + 1))}\n`
+    : ``
+  const padding = `  `.repeat(depth)
+  return (
+    `${padding}<${node.tag}${props ? ` ${props}` : ``}>` +
+    `${children}` +
+    `${padding}</${node.tag}>`
+  )
+}
+
+function serializeText(node: TestText, depth: number): string {
+  return `  `.repeat(depth) + node.text
+}