[date] Fixed: wrong incrementation of month in date_range function (closes #186698).

Add a unit test.

2 files changed, 8 insertions, 1 deletions

diff --git a/date.py b/date.py
index ae5025e..bd660c0 100644
--- a/date.py
+++ b/date.py
@@ -188,8 +188,8 @@ def date_range(begin, end, incday=None, incmonth=None):
     end = todate(end)
     if incmonth:
         while begin < end:
-            begin = next_month(begin, incmonth)
             yield begin
+            begin = next_month(begin, incmonth)
     else:
         incr = get_step(begin, incday or 1)
         while begin < end:
diff --git a/test/unittest_date.py b/test/unittest_date.py
index 0aa1de8..ba1522c 100644
--- a/test/unittest_date.py
+++ b/test/unittest_date.py
@@ -138,6 +138,13 @@ class DateTC(TestCase):
         date = ticks2datetime(ticks)
         self.assertEqual(ustrftime(date, '%Y-%m-%d'), u'1899-12-31')
 
+    def test_month(self):
+        """enumerate months"""
+        r = list(date_range(self.datecls(2006, 5, 6), self.datecls(2006, 8, 27),
+                            incmonth=True))
+        expected = [self.datecls(2006, 5, 6), self.datecls(2006, 6, 1), self.datecls(2006, 7, 1), self.datecls(2006, 8, 1)]
+        self.assertListEqual(expected, r)
+
 
 class MxDateTC(DateTC):
     datecls = mxDate