config_service: add last import validation and tests

appengine/config_service/ui/src/config-ui/front-page.html

 <!--
   Copyright 2017 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 -->
 
 <link rel="import" href="../../bower_components/app-layout/app-layout.html">
 <link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html">
 <link rel="import" href="../../bower_components/paper-button/paper-button.html">
 <link rel="import" href="../../bower_components/paper-search/paper-search-bar.html">
@@ skipping 20 matching lines @@
         border-width: 2px;
         width: 40%;
         height: 100%;
         margin: auto;
       }
     </style>
 
     <iron-ajax
         auto
         id="requestConfigs"
-        url="/_ah/api/config/v1/config-sets"
+        url="/_ah/api/config/v1/config-sets?include_last_import_attempt=true"
         handle-as="json"
         on-response="_onGotConfigSets"
         headers="[[auth_headers]]">
     </iron-ajax>
     
     <div class="search-bar">
       <paper-search-bar query="{{query}}"></paper-search-bar>
     </div>
     
     <div class="config-list">
       <template is="dom-if" if="[[isLoading]]">
         <div class="center">Fetching config sets...</div>
       </template>
       <template is="dom-if" if="[[_not(isLoading)]]">
         <template is="dom-if" if="[[_isEmpty(searchResults)]]">
           <div class="center">No config sets found.</div>
         </template>
         <template is="dom-if" if="[[_not(_isEmpty(searchResults))]]">
           <template is="dom-repeat" items="[[searchResults]]" as="config">
-            <config-set-card name="[[config.config_set]]" on-tap="_handleClick"></config-set-card>
+            <config-set-card 
+                name="[[config.config_set]]" 
+                last-import-attempt="[[_getLastImportAttempt(config.last_import_attempt)]]" 
+                on-tap="_handleClick">
+            </config-set-card>
           </template>
         </template>
       </template>
     </div>
   </template>
 
   <script>
     Polymer({
       is: 'front-page',
 
@@ skipping 12 matching lines @@
           type: String,
           observer: '_updateSearchResults'
         },
 
         searchResults: {
           type: Array,
           value: () => []
         }
       },
 
+      _getLastImportAttempt: function(lastImportAttempt) {
+        if (lastImportAttempt) {
+          return lastImportAttempt;
+        } else {
+          return null;
+        }
+      },
+
       _isEmpty: function(array) {
         return array.length === 0;
       },
 
       _onGotConfigSets: function(event) {
         this.configSetList = event.detail.response.config_sets;
         this._updateSearchResults();
         this.isLoading = false;
       },
 
       _not: function(b) {
         return !b;
       },
 
       _updateSearchResults: function() {
         this.searchResults = this.configSetList.filter(e => e.config_set.includes(this.query));
       },
 
       _handleClick: function(event) {
         window.location = window.location.href + event.model.config.config_set;
       },
 
     });
   </script>
 </dom-module>