* Add tests for tokens api

tests/test_tokens_api.py

@@ -0,0 +1,16 @@
+from __future__ import unicode_literals
+from spacy.en import English
+
+import pytest
+
+@pytest.fixture
+def tokens():
+    nlp = English()
+    return nlp(u'Give it back! He pleaded.')
+
+
+def test_getitem(tokens):
+    assert tokens[0].orth_ == 'Give'
+    assert tokens[-1].orth_ == '.'
+    with pytest.raises(IndexError):
+        tokens[len(tokens)]