triggers panel: tests for schema migration

dist/panel-triggers/migrations.js

@@ -4,11 +4,20 @@ System.register([], function (_export, _context) {
   "use strict";
 
   function migratePanelSchema(panel) {
+    if (isEmptyPanel(panel)) {
+      return panel;
+    }
+
     var schemaVersion = getSchemaVersion(panel);
     switch (schemaVersion) {
       case 1:
         panel.datasources = [panel.datasource];
+        panel.targets = {};
         panel.targets[panel.datasources[0]] = panel.triggers;
+
+        // delete old props
+        delete panel.triggers;
+        delete panel.datasource;
         break;
     }
 
@@ -20,6 +29,10 @@ System.register([], function (_export, _context) {
   function getSchemaVersion(panel) {
     return panel.schemaVersion || 1;
   }
+
+  function isEmptyPanel(panel) {
+    return !panel.datasource && !panel.datasources && !panel.triggers && !panel.targets;
+  }
   return {
     setters: [],
     execute: function () {}