Add test for #1868: Vocab.__contains__ with ints

spacy/tests/regression/test_issue1868.py

@@ -0,0 +1,13 @@
+'''Test Vocab.__contains__ works with int keys'''
+from __future__ import unicode_literals
+
+from ... vocab import Vocab
+
+def test_issue1868():
+    vocab = Vocab()
+    lex = vocab['hello']
+    assert lex.orth in vocab
+    assert lex.orth_ in vocab
+    assert 'some string' not in vocab
+    int_id = vocab.strings.add('some string')
+    assert int_id not in vocab