* Add test for parse tree navigation

tests/test_parse_navigate.py

@@ -0,0 +1,28 @@
+from __future__ import unicode_literals
+from os import path
+import codecs
+
+from spacy.en import English
+
+import pytest
+
+
+@pytest.fixture
+def sun_text():
+    with codecs.open(path.join(path.dirname(__file__), 'sun.txt'), 'r', 'utf8') as file_:
+        text = file_.read()
+    return text
+
+
+@pytest.fixture
+def nlp():
+    return English()
+
+
+def test_consistency(nlp, sun_text):
+    tokens = nlp(sun_text)
+    for head in tokens:
+        for child in head.lefts:
+            assert child.head is head
+        for child in head.rights:
+            assert child.head is head