add hypothesis

Author: Thomas Grainger

.gitignore

@@ -32,6 +32,7 @@ pip-log.txt
 .tox
 nosetests.xml
 .noseids
+.hypothesis
 
 # Translations
 *.mo

tests/test_apply.py

@@ -1,15 +1,20 @@
 # -*- coding: utf-8 -*-
 
-import whatthepatch as wtp
-from whatthepatch import exceptions
+import unittest
+import difflib
 
+from hypothesis import given, assume
+from hypothesis import strategies as st
 from nose.tools import assert_raises
-import unittest
+
+from whatthepatch import exceptions
+import whatthepatch as wtp
 
 
 def _apply(src, diff_text, reverse=False, use_patch=False):
-    diff = next(wtp.parse_patch(diff_text))
-    return wtp.apply.apply_diff(diff, src, reverse, use_patch)
+    diff = list(wtp.parse_patch(diff_text))
+    assert len(diff) == 1
+    return wtp.apply.apply_diff(diff[0], src, reverse, use_patch)
 
 
 def _apply_r(src, diff_text, reverse=True, use_patch=False):
@@ -147,5 +152,28 @@ def test_diff_ed(self):
         self.assertEqual(new_text, (self.tzu, None))
 
 
+    @given(
+        st.text(), st.text(), st.text(), st.text(), st.datetimes(),
+        st.datetimes(), st.integers(),
+    )
+    def test_apply_reverse(self, a, b, fromfile, tofile, fromdate, todate, n):
+        diff = list(difflib.unified_diff(
+            a.split('\n'),
+            b.split('\n'),
+            fromfile=fromfile,
+            tofile=tofile,
+            fromfiledate=fromdate.isoformat(),
+            tofiledate=todate.isoformat(),
+            n=n,
+            lineterm='',
+        ))
+        assume(diff)
+        a_str = a
+        b_str = b
+
+        self.assertEqual(_apply(a_str.split('\n'), diff[:]), b_str.split('\n'))
+        self.assertEqual(_apply_r(b_str.split('\n'), diff[:]), a_str.split('\n'))
+
+
 if __name__ == '__main__':
     unittest.main()

tox.ini

@@ -4,7 +4,9 @@ envlist = py{27,34,35,36,37}, lint
 [testenv]
 commands = nosetests --with-doctest --doctest-extension=rst {posargs}
 deps =
+    pytz
     nose==1.3.7
+    hypothesis==4.14.0
 
 [testenv:lint]
 deps =