* Added a substantial number of edge case and argument tests for

  the itertoolsmodule.
* Taught itertools.repeat(obj, n) to treat negative repeat counts as
  zero.  This behavior matches that for sequences and prevents
  infinite loops.

Lib/test/test_itertools.py

@@ -2,63 +2,119 @@ import unittest
 from test import test_support
 from itertools import *
 import sys
+import operator
+
+def onearg(x):
+    'Test function of one argument'
+    return x
+
+def errfunc(*args):
+    'Test function that raises an error'
+    raise ValueError
+
+def gen3():
+    'Non-restartable source sequence'
+    for i in (0, 1, 2):
+        yield i
+
+def isEven(x):
+    'Test predicate'
+    return x%2==0
+
+class StopNow:
+    'Class emulating an empty iterable.'
+    def __iter__(self):
+        return self
+    def next(self):
+        raise StopIteration
 
 class TestBasicOps(unittest.TestCase):
     def test_chain(self):
         self.assertEqual(list(chain('abc', 'def')), list('abcdef'))
+        self.assertEqual(list(chain('abc')), list('abc'))
+        self.assertEqual(list(chain('')), [])
+        self.assertRaises(TypeError, chain, 2, 3)
 
     def test_count(self):
         self.assertEqual(zip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
         self.assertEqual(zip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
         self.assertRaises(TypeError, count, 2, 3)
+        self.assertRaises(TypeError, count, 'a')
+        c = count(sys.maxint-2)   # verify that rollover doesn't crash
+        c.next(); c.next(); c.next(); c.next(); c.next()
 
     def test_cycle(self):
         self.assertEqual(list(islice(cycle('abc'),10)), list('abcabcabca'))
         self.assertEqual(list(cycle('')), [])
+        self.assertRaises(TypeError, cycle)
+        self.assertRaises(TypeError, cycle, 5)
+        self.assertEqual(list(islice(cycle(gen3()),10)), [0,1,2,0,1,2,0,1,2,0])
 
     def test_ifilter(self):
-        def isEven(x):
-            return x%2==0
         self.assertEqual(list(ifilter(isEven, range(6))), [0,2,4])
         self.assertEqual(list(ifilter(None, [0,1,0,2,0])), [1,2])
         self.assertRaises(TypeError, ifilter)
-        self.assertRaises(TypeError, ifilter, 3)
+        self.assertRaises(TypeError, ifilter, lambda x:x)
+        self.assertRaises(TypeError, ifilter, lambda x:x, range(6), 7)
         self.assertRaises(TypeError, ifilter, isEven, 3)
+        self.assertRaises(TypeError, ifilter(range(6), range(6)).next)
 
     def test_ifilterfalse(self):
-        def isEven(x):
-            return x%2==0
         self.assertEqual(list(ifilterfalse(isEven, range(6))), [1,3,5])
         self.assertEqual(list(ifilterfalse(None, [0,1,0,2,0])), [0,0,0])
         self.assertRaises(TypeError, ifilterfalse)
-        self.assertRaises(TypeError, ifilterfalse, 3)
+        self.assertRaises(TypeError, ifilterfalse, lambda x:x)
+        self.assertRaises(TypeError, ifilterfalse, lambda x:x, range(6), 7)
         self.assertRaises(TypeError, ifilterfalse, isEven, 3)
+        self.assertRaises(TypeError, ifilterfalse(range(6), range(6)).next)
 
     def test_izip(self):
         ans = [(x,y) for x, y in izip('abc',count())]
         self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
+        self.assertEqual(list(izip('abc', range(6))), zip('abc', range(6)))
+        self.assertEqual(list(izip('abcdef', range(3))), zip('abcdef', range(3)))
+        self.assertEqual(list(izip('abcdef')), zip('abcdef'))
         self.assertRaises(TypeError, izip)
+        self.assertRaises(TypeError, izip, 3)
+        self.assertRaises(TypeError, izip, range(3), 3)
+        # Check tuple re-use (implementation detail)
+        self.assertEqual([tuple(list(pair)) for pair in izip('abc', 'def')],
+                         zip('abc', 'def'))
+        ids = map(id, izip('abc', 'def'))
+        self.assertEqual(min(ids), max(ids))
 
     def test_repeat(self):
         self.assertEqual(zip(xrange(3),repeat('a')),
                          [(0, 'a'), (1, 'a'), (2, 'a')])
         self.assertEqual(list(repeat('a', 3)), ['a', 'a', 'a'])
+        self.assertEqual(list(repeat('a', 0)), [])
+        self.assertEqual(list(repeat('a', -3)), [])
         self.assertRaises(TypeError, repeat)
+        self.assertRaises(TypeError, repeat, None, 3, 4)
+        self.assertRaises(TypeError, repeat, None, 'a')
 
     def test_imap(self):
-        import operator
         self.assertEqual(list(imap(operator.pow, range(3), range(1,7))),
                          [0**1, 1**2, 2**3])
         self.assertEqual(list(imap(None, 'abc', range(5))),
                          [('a',0),('b',1),('c',2)])
+        self.assertEqual(list(imap(operator.pow, [])), [])
         self.assertRaises(TypeError, imap)
         self.assertRaises(TypeError, imap, operator.neg)
+        self.assertRaises(TypeError, imap(10, range(5)).next)
+        self.assertRaises(ValueError, imap(errfunc, [4], [5]).next)
+        self.assertRaises(TypeError, imap(onearg, [4], [5]).next)
 
     def test_starmap(self):
-        import operator
         self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
                          [0**1, 1**2, 2**3])
+        self.assertEqual(list(starmap(operator.pow, [])), [])
         self.assertRaises(TypeError, list, starmap(operator.pow, [[4,5]]))
+        self.assertRaises(TypeError, starmap)
+        self.assertRaises(TypeError, starmap, operator.pow, [(4,5)], 'extra')
+        self.assertRaises(TypeError, starmap(10, [(4,5)]).next)
+        self.assertRaises(ValueError, starmap(errfunc, [(4,5)]).next)
+        self.assertRaises(TypeError, starmap(onearg, [(4,5)]).next)
 
     def test_islice(self):
         for args in [          # islice(args) should agree with range(args)
@@ -100,20 +156,25 @@ class TestBasicOps(unittest.TestCase):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
         underten = lambda x: x<10
         self.assertEqual(list(takewhile(underten, data)), [1, 3, 5])
+        self.assertEqual(list(takewhile(underten, [])), [])
+        self.assertRaises(TypeError, takewhile)
+        self.assertRaises(TypeError, takewhile, operator.pow)
+        self.assertRaises(TypeError, takewhile, operator.pow, [(4,5)], 'extra')
+        self.assertRaises(TypeError, takewhile(10, [(4,5)]).next)
+        self.assertRaises(ValueError, takewhile(errfunc, [(4,5)]).next)
 
     def test_dropwhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
         underten = lambda x: x<10
         self.assertEqual(list(dropwhile(underten, data)), [20, 2, 4, 6, 8])
+        self.assertEqual(list(dropwhile(underten, [])), [])
+        self.assertRaises(TypeError, dropwhile)
+        self.assertRaises(TypeError, dropwhile, operator.pow)
+        self.assertRaises(TypeError, dropwhile, operator.pow, [(4,5)], 'extra')
+        self.assertRaises(TypeError, dropwhile(10, [(4,5)]).next)
+        self.assertRaises(ValueError, dropwhile(errfunc, [(4,5)]).next)
 
     def test_StopIteration(self):
-        class StopNow:
-            """Test support class .  Emulates an empty iterable."""
-            def __iter__(self):
-                return self
-            def next(self):
-                raise StopIteration
-
         for f in (chain, cycle, izip):
             self.assertRaises(StopIteration, f([]).next)
             self.assertRaises(StopIteration, f(StopNow()).next)

Modules/itertoolsmodule.c

@@ -1691,6 +1691,9 @@ repeat_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 	if (!PyArg_ParseTuple(args, "O|l:repeat", &element, &cnt))
 		return NULL;
 
+	if (PyTuple_Size(args) == 2 && cnt < 0)
+		cnt = 0;
+
 	ro = (repeatobject *)type->tp_alloc(type, 0);
 	if (ro == NULL)
 		return NULL;