Make deque.rotate() smarter. Beef-up related tests.

1 files changed, 43 insertions, 9 deletions

diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 016c2ae..f3bc59f 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -41,16 +41,50 @@ class TestBasic(unittest.TestCase):
         self.assertEqual(list(d), list(reversed('abcd')))
 
     def test_rotate(self):
-        s = 'abcde'
+        s = tuple('abcde')
+        n = len(s)
+
+        d = deque(s)
+        d.rotate(1)             # verify rot(1)
+        self.assertEqual(''.join(d), 'eabcd')
+
+        d = deque(s)
+        d.rotate(-1)            # verify rot(-1)
+        self.assertEqual(''.join(d), 'bcdea')
+        d.rotate()              # check default to 1
+        self.assertEqual(tuple(d), s)
+
+        for i in xrange(n*3):
+            d = deque(s)
+            e = deque(d)
+            d.rotate(i)         # check vs. rot(1) n times
+            for j in xrange(i):
+                e.rotate(1)
+            self.assertEqual(tuple(d), tuple(e))
+            d.rotate(-i)        # check that it works in reverse
+            self.assertEqual(tuple(d), s)
+            e.rotate(n-i)       # check that it wraps forward
+            self.assertEqual(tuple(e), s)
+
+        for i in xrange(n*3):
+            d = deque(s)
+            e = deque(d)
+            d.rotate(-i)
+            for j in xrange(i):
+                e.rotate(-1)    # check vs. rot(-1) n times
+            self.assertEqual(tuple(d), tuple(e))
+            d.rotate(i)         # check that it works in reverse
+            self.assertEqual(tuple(d), s)
+            e.rotate(i-n)       # check that it wraps backaround
+            self.assertEqual(tuple(e), s)
+
         d = deque(s)
-        d.rotate(2)
-        self.assertEqual(''.join(d), 'deabc')
-        d.rotate(3)
-        self.assertEqual(''.join(d), s)
-        d.rotate(-3)
-        self.assertEqual(''.join(d), 'deabc')
-        d.rotate(-15)
-        self.assertEqual(''.join(d), 'deabc')
+        e = deque(s)
+        e.rotate(BIG+17)        # verify on long series of rotates
+        dr = d.rotate
+        for i in xrange(BIG+17):
+            dr()
+        self.assertEqual(tuple(d), tuple(e))
 
     def test_len(self):
         d = deque('ab')