Add test of simple textcat workflow

spacy/tests/textcat/test_textcat.py

@@ -0,0 +1,19 @@
+from __future__ import unicode_literals
+from ...language import Language
+
+def test_simple_train():
+    nlp = Language()
+
+    nlp.add_pipe(nlp.create_pipe('textcat'))
+    nlp.get_pipe('textcat').add_label('is_good')
+
+    nlp.begin_training()
+
+    for i in range(5):
+        for text, answer in [('aaaa', 1.), ('bbbb', 0), ('aa', 1.),
+                            ('bbbbbbbbb', 0.), ('aaaaaa', 1)]:
+            nlp.update([text], [{'cats': {'answer': answer}}])
+    doc = nlp(u'aaa')
+    assert 'is_good' in doc.cats
+    assert doc.cats['is_good'] >= 0.5
+