* Add tests for new merge() method

tests/test_merge.py

@@ -0,0 +1,32 @@
+from __future__ import unicode_literals
+
+import pytest
+
+from spacy.en import English
+
+NLU = English()
+
+
+def test_merge_tokens():
+    tokens = NLU(u'7 a.m. start.')
+    assert len(tokens) == 4
+    assert tokens[0].head.orth_ == 'a.m.'
+    assert tokens[1].head.orth_ == 'start'
+    tokens.merge(0, len('7 a.m.'), 'CD', '7 a.m.', 'TIME')
+    assert len(tokens) == 3
+    assert tokens[0].orth_ == '7 a.m.'
+    assert tokens[0].head.orth_ == 'start'
+
+
+def test_merge_heads():
+    tokens = NLU(u'I found a pilates class near work.')
+    assert len(tokens) == 8
+    tokens.merge(tokens[3].idx, tokens[4].idx + len(tokens[4]), tokens[4].tag_,
+                 'pilates class', 'O')
+    assert len(tokens) == 7
+    assert tokens[0].head.i == 1
+    assert tokens[1].head.i == 1
+    assert tokens[2].head.i == 3
+    assert tokens[3].head.i == 1
+    assert tokens[4].head.i in [1, 3]
+    assert tokens[5].head.i == 4