support comment option in template (#897)

* support comment option in template

* Update loader.js

* Update template-comment.vue

Author: Kingwl

lib/loader.js

@@ -89,10 +89,12 @@ module.exports = function (content) {
   var output = ''
   var parts = parse(content, fileName, this.sourceMap)
   var hasScoped = parts.styles.some(function (s) { return s.scoped })
+  var hasComment = parts.template && parts.template.attrs.comments
 
   var templateCompilerOptions = '?' + JSON.stringify({
     id: moduleId,
     hasScoped: hasScoped,
+    hasComment: hasComment,
     transformToRequire: options.transformToRequire,
     preserveWhitespace: options.preserveWhitespace,
     buble: options.buble,

lib/template-compiler/index.js

@@ -23,7 +23,8 @@ module.exports = function (html) {
   var compilerOptions = {
     preserveWhitespace: options.preserveWhitespace,
     modules: defaultModules.concat(userModules || []),
-    scopeId: options.hasScoped ? options.id : null
+    scopeId: options.hasScoped ? options.id : null,
+    comments: options.hasComment
   }
 
   var compile = isServer && compiler.ssrCompile && vueOptions.optimizeSSR !== false

test/fixtures/template-comment.vue

@@ -0,0 +1,16 @@
+<template comments>
+  <div>
+    <h2 class="red">{{msg}}</h2><!-- comment here -->
+  </div>
+</template>
+
+<script>
+export default {
+  comments: true,
+  data () {
+    return {
+      msg: 'Hello from Component A!'
+    }
+  }
+}
+</script>

test/test.js

@@ -98,11 +98,18 @@ function mockRender (options, data) {
       children: children
     }
   }
+  function e (text = '') {
+    return {
+      text:  text,
+      isComment: true
+    }
+  }
   return options.render.call(Object.assign({
     _v (val) {
       return val
     },
     _self: {},
+    _e: e,
     $createElement: h,
     _m (index) {
       return options.staticRenderFns[index].call(this)
@@ -907,4 +914,22 @@ describe('vue-loader', function () {
       done()
     })
   })
+
+  it('template with comments', done => {
+    test({
+      entry: './test/fixtures/template-comment.vue'
+    }, (window, module, rawModule) => {
+      expect(module.comments).to.equal(true)
+      var vnode = mockRender(module, {
+        msg: 'hi'
+      })
+      expect(vnode.tag).to.equal('div')
+      expect(vnode.children.length).to.equal(2)
+      expect(vnode.children[0].data.staticClass).to.equal('red')
+      expect(vnode.children[0].children[0]).to.equal('hi')
+      expect(vnode.children[1].isComment).to.true
+      expect(vnode.children[1].text).to.equal(' comment here ')
+      done()
+    })
+  })
 })