test: update fragment tests

packages/runtime-core/src/createRenderer.ts

@@ -694,7 +694,9 @@ export function createRenderer(options: RendererOptions) {
       if (prevShapeFlag & ShapeFlags.ARRAY_CHILDREN) {
         unmountChildren(c1 as VNode[], parentComponent)
       }
-      hostSetElementText(container, c2 as string)
+      if (c2 !== c1) {
+        hostSetElementText(container, c2 as string)
+      }
     } else {
       if (prevShapeFlag & ShapeFlags.TEXT_CHILDREN) {
         hostSetElementText(container, '')

packages/runtime-core/src/h.ts

@@ -0,0 +1,49 @@
+import { VNodeTypes, VNode, createVNode } from './vnode'
+import { isObject, isArray } from '@vue/shared'
+
+// `h` is a more user-friendly version of `createVNode` that allows omitting the
+// props when possible. It is intended for manually written render functions.
+// Compiler-generated code uses `createVNode` because
+// 1. it is monomorphic and avoids the extra call overhead
+// 2. it allows specifying patchFlags for optimization
+
+/*
+// type only
+h('div')
+
+// type + props
+h('div', {})
+
+// type + omit props + children
+// Omit props does NOT support named slots
+h('div', []) // array
+h('div', () => {}) // default slot
+h('div', 'foo') // text
+
+// type + props + children
+h('div', {}, []) // array
+h('div', {}, () => {}) // default slot
+h('div', {}, {}) // named slots
+h('div', {}, 'foo') // text
+
+// named slots without props requires explicit `null` to avoid ambiguity
+h('div', null, {})
+**/
+
+export function h(
+  type: VNodeTypes,
+  propsOrChildren?: any,
+  children?: any
+): VNode {
+  if (arguments.length === 2) {
+    if (isObject(propsOrChildren) && !isArray(propsOrChildren)) {
+      // props without children
+      return createVNode(type, propsOrChildren)
+    } else {
+      // omit props
+      return createVNode(type, null, propsOrChildren)
+    }
+  } else {
+    return createVNode(type, propsOrChildren, children)
+  }
+}

packages/runtime-core/src/index.ts

@@ -10,6 +10,7 @@ export * from './apiInject'
 // Advanced API ----------------------------------------------------------------
 
 // For raw render function users
+export { h } from './h'
 export {
   createVNode,
   cloneVNode,

packages/runtime-core/src/vnode.ts

@@ -18,7 +18,7 @@ export const Text = Symbol('Text')
 export const Empty = Symbol('Empty')
 export const Portal = Symbol('Portal')
 
-type VNodeTypes =
+export type VNodeTypes =
   | string
   | Function
   | Object