fix(model): always emit 'index', even if no indexes

Re: #3347

Author: vkarpov15

lib/model.js

@@ -929,14 +929,6 @@ Model.ensureIndexes = function ensureIndexes(options, callback) {
 
 function _ensureIndexes(model, options, callback) {
   var indexes = model.schema.indexes();
-  if (!indexes.length) {
-    setImmediate(function() {
-      callback && callback();
-    });
-    return;
-  }
-  // Indexes are created one-by-one to support how MongoDB < 2.4 deals
-  // with background indexes.
 
   var done = function(err) {
     if (err && model.schema.options.emitIndexErrors) {
@@ -946,6 +938,15 @@ function _ensureIndexes(model, options, callback) {
     callback && callback(err);
   };
 
+  if (!indexes.length) {
+    setImmediate(function() {
+      done();
+    });
+    return;
+  }
+  // Indexes are created one-by-one to support how MongoDB < 2.4 deals
+  // with background indexes.
+
   var indexSingleDone = function(err, fields, options, name) {
     model.emit('index-single-done', err, fields, options, name);
   };

test/model.indexes.test.js

@@ -226,16 +226,17 @@ describe('model', function() {
           schema = new Schema({name: {type: String}}),
           Test = db.model('IndexError', schema, 'x' + random());
 
-      Test.on('index', function(err) {
-        db.close();
-        assert.ok(/E11000 duplicate key error/.test(err.message), err);
-        done();
-      });
-
       Test.create({name: 'hi'}, {name: 'hi'}, function(err) {
         assert.strictEqual(err, null);
         Test.schema.index({name: 1}, {unique: true});
         Test.schema.index({other: 1});
+
+        Test.on('index', function(err) {
+          db.close();
+          assert.ok(/E11000 duplicate key error/.test(err.message), err);
+          done();
+        });
+
         Test.init();
       });
     });