Fix #1230. Fix word2vec reset_from bug in v1.0.1 and added unittest

gensim/models/word2vec.py

@@ -738,8 +738,8 @@ def reset_from(self, other_model):
         Borrow shareable pre-built structures (like vocab) from the other_model. Useful
         if testing multiple models in parallel on the same corpus.
         """
-        self.wv.vocab = other_model.vocab
-        self.wv.index2word = other_model.index2word
+        self.wv.vocab = other_model.wv.vocab
+        self.wv.index2word = other_model.wv.index2word
         self.cum_table = other_model.cum_table
         self.corpus_count = other_model.corpus_count
         self.reset_weights()

gensim/test/test_word2vec.py

@@ -678,6 +678,16 @@ def test_sentences_should_not_be_a_generator(self):
     def testLoadOnClassError(self):
         """Test if exception is raised when loading word2vec model on instance"""
         self.assertRaises(AttributeError, load_on_instance)
+
+    def test_reset_from(self):
+        """Test if reset_from() uses pre-built structures from other model"""
+        model = word2vec.Word2Vec(sentences, min_count=1)
+        other_model = word2vec.Word2Vec(new_sentences, min_count=1) 
+        other_vocab = other_model.wv.vocab
+        model.reset_from(other_model)
+        self.assertEqual(model.wv.vocab, other_vocab)
+
+
 #endclass TestWord2VecModel
 
 class TestWMD(unittest.TestCase):