Fixed bug #7, overlap with empty range incorrectly returns True

doc/changelog.rst

@@ -5,6 +5,14 @@ first `0.1` release does not properly adhere to this. Unless explicitly stated,
 changes are made by `Andreas Runfalk <https://github.com/runfalk>`_.
 
 
+Version 1.0.0
+-------------
+Released on <unreleased>
+
+- Fixed overlap with empty range incorrectly returns ``True``
+  (`bug #7 <https://github.com/runfalk/spans/issues/7>`_)
+
+
 Version 0.5.0
 -------------
 Released on 16th April, 2017

spans/types.py

@@ -377,7 +377,7 @@ def overlap(self, other):
         This is the same as the ``&&`` operator for two ranges in PostgreSQL.
 
         :param other: Range to test against.
-        :return: ``True`` if ranges intersect, otherwise ``False``.
+        :return: ``True`` if ranges overlap, otherwise ``False``.
         :raises TypeError: If `other` is of another type than this range.
 
         .. seealso::
@@ -387,7 +387,7 @@ def overlap(self, other):
 
         # Special case for empty ranges
         if not self or not other:
-            return True
+            return False
 
         if self < other:
             a, b = self, other

tests/test_range.py

@@ -439,3 +439,7 @@ def test_intersection(a, b, intersection):
 def test_pickling():
     span = intrange(1, 10)
     assert span == pickle.loads(pickle.dumps(span))
+
+
+def test_bug7_overlap_empty():
+    assert not intrange(1, 10).overlap(intrange.empty())