test(compiler-ssr): v-for tests

packages/compiler-ssr/src/transforms/ssrVFor.ts

@@ -5,7 +5,8 @@ import {
   createCallExpression,
   createFunctionExpression,
   createForLoopParams,
-  createBlockStatement
+  createBlockStatement,
+  NodeTypes
 } from '@vue/compiler-dom'
 import {
   SSRTransformContext,
@@ -23,16 +24,28 @@ export const ssrTransformFor = createStructuralDirectiveTransform(
 // This is called during the 2nd transform pass to construct the SSR-sepcific
 // codegen nodes.
 export function processFor(node: ForNode, context: SSRTransformContext) {
+  const childContext = createChildContext(context)
+  const needFragmentWrapper =
+    node.children.length !== 1 || node.children[0].type !== NodeTypes.ELEMENT
+  if (needFragmentWrapper) {
+    childContext.pushStringPart(`<!---->`)
+  }
+  processChildren(node.children, childContext)
+  if (needFragmentWrapper) {
+    childContext.pushStringPart(`<!---->`)
+  }
   const renderLoop = createFunctionExpression(
     createForLoopParams(node.parseResult)
   )
-  const childContext = createChildContext(context)
-  processChildren(node.children, childContext)
   renderLoop.body = createBlockStatement(childContext.body)
+
+  // v-for always renders a fragment
+  context.pushStringPart(`<!---->`)
   context.pushStatement(
     createCallExpression(context.helper(SSR_RENDER_LIST), [
       node.source,
       renderLoop
     ])
   )
+  context.pushStringPart(`<!---->`)
 }

packages/compiler-ssr/src/transforms/ssrVIf.ts

@@ -59,15 +59,15 @@ function processIfBranch(
   context: SSRTransformContext
 ): BlockStatement {
   const { children } = branch
-  const firstChild = children[0]
-  // TODO optimize away nested fragments when the only child is a ForNode
   const needFragmentWrapper =
-    children.length !== 1 || firstChild.type !== NodeTypes.ELEMENT
+    (children.length !== 1 || children[0].type !== NodeTypes.ELEMENT) &&
+    // optimize away nested fragments when the only child is a ForNode
+    !(children.length === 1 && children[0].type === NodeTypes.FOR)
   const childContext = createChildContext(context)
   if (needFragmentWrapper) {
     childContext.pushStringPart(`<!---->`)
   }
-  processChildren(branch.children, childContext)
+  processChildren(children, childContext)
   if (needFragmentWrapper) {
     childContext.pushStringPart(`<!---->`)
   }