summaryrefslogtreecommitdiffstats
path: root/Lib/test/test_itertools.py
blob: 73e880971d91bd627f13f04c59a51512a699c99e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
import unittest
from test import test_support
from itertools import *
import sys
import operator
import random

def onearg(x):
    'Test function of one argument'
    return 2*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

def isOdd(x):
    'Test predicate'
    return x%2==1

class StopNow:
    'Class emulating an empty iterable.'
    def __iter__(self):
        return self
    def next(self):
        raise StopIteration

def take(n, seq):
    'Convenience function for partially consuming a long of infinite iterable'
    return list(islice(seq, n))

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.assertEqual(take(4, chain('abc', 'def')), list('abcd'))
        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.assertEqual(take(2, zip('abc',count(3))), [('a', 3), ('b', 4)])
        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(take(10, cycle('abc')), 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_groupby(self):
        # Check whether it accepts arguments correctly
        self.assertEqual([], list(groupby([])))
        self.assertEqual([], list(groupby([], key=id)))
        self.assertRaises(TypeError, list, groupby('abc', []))
        self.assertRaises(TypeError, groupby, None)

        # Check normal input
        s = [(0, 10, 20), (0, 11,21), (0,12,21), (1,13,21), (1,14,22),
             (2,15,22), (3,16,23), (3,17,23)]
        dup = []
        for k, g in groupby(s, lambda r:r[0]):
            for elem in g:
                self.assertEqual(k, elem[0])
                dup.append(elem)
        self.assertEqual(s, dup)

        # Check nested case
        dup = []
        for k, g in groupby(s, lambda r:r[0]):
            for ik, ig in groupby(g, lambda r:r[2]):
                for elem in ig:
                    self.assertEqual(k, elem[0])
                    self.assertEqual(ik, elem[2])
                    dup.append(elem)
        self.assertEqual(s, dup)

        # Check case where inner iterator is not used
        keys = [k for k, g in groupby(s, lambda r:r[0])]
        expectedkeys = set([r[0] for r in s])
        self.assertEqual(set(keys), expectedkeys)
        self.assertEqual(len(keys), len(expectedkeys))

        # Exercise pipes and filters style
        s = 'abracadabra'
        # sort s | uniq
        r = [k for k, g in groupby(sorted(s))]
        self.assertEqual(r, ['a', 'b', 'c', 'd', 'r'])
        # sort s | uniq -d
        r = [k for k, g in groupby(sorted(s)) if list(islice(g,1,2))]
        self.assertEqual(r, ['a', 'b', 'r'])
        # sort s | uniq -c
        r = [(len(list(g)), k) for k, g in groupby(sorted(s))]
        self.assertEqual(r, [(5, 'a'), (2, 'b'), (1, 'c'), (1, 'd'), (2, 'r')])
        # sort s | uniq -c | sort -rn | head -3
        r = sorted([(len(list(g)) , k) for k, g in groupby(sorted(s))], reverse=True)[:3]
        self.assertEqual(r, [(5, 'a'), (2, 'r'), (2, 'b')])

        # iter.next failure
        class ExpectedError(Exception):
            pass
        def delayed_raise(n=0):
            for i in range(n):
                yield 'yo'
            raise ExpectedError
        def gulp(iterable, keyp=None, func=list):
            return [func(g) for k, g in groupby(iterable, keyp)]

        # iter.next failure on outer object
        self.assertRaises(ExpectedError, gulp, delayed_raise(0))
        # iter.next failure on inner object
        self.assertRaises(ExpectedError, gulp, delayed_raise(1))

        # __cmp__ failure
        class DummyCmp:
            def __cmp__(self, dst):
                raise ExpectedError
        s = [DummyCmp(), DummyCmp(), None]

        # __cmp__ failure on outer object
        self.assertRaises(ExpectedError, gulp, s, func=id)
        # __cmp__ failure on inner object
        self.assertRaises(ExpectedError, gulp, s)

        # keyfunc failure
        def keyfunc(obj):
            if keyfunc.skip > 0:
                keyfunc.skip -= 1
                return obj
            else:
                raise ExpectedError

        # keyfunc failure on outer object
        keyfunc.skip = 0
        self.assertRaises(ExpectedError, gulp, [None], keyfunc)
        keyfunc.skip = 1
        self.assertRaises(ExpectedError, gulp, [None, None], keyfunc)

    def test_ifilter(self):
        self.assertEqual(list(ifilter(isEven, range(6))), [0,2,4])
        self.assertEqual(list(ifilter(None, [0,1,0,2,0])), [1,2])
        self.assertEqual(take(4, ifilter(isEven, count())), [0,2,4,6])
        self.assertRaises(TypeError, ifilter)
        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):
        self.assertEqual(list(ifilterfalse(isEven, range(6))), [1,3,5])
        self.assertEqual(list(ifilterfalse(None, [0,1,0,2,0])), [0,0,0])
        self.assertEqual(take(4, ifilterfalse(isEven, count())), [1,3,5,7])
        self.assertRaises(TypeError, ifilterfalse)
        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(take(3,izip('abcdef', count())), zip('abcdef', range(3)))
        self.assertEqual(list(izip('abcdef')), zip('abcdef'))
        self.assertEqual(list(izip()), zip())
        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'))
        self.assertEqual([pair for pair in izip('abc', 'def')],
                         zip('abc', 'def'))
        ids = map(id, izip('abc', 'def'))
        self.assertEqual(min(ids), max(ids))
        ids = map(id, list(izip('abc', 'def')))
        self.assertEqual(len(dict.fromkeys(ids)), len(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(take(3, repeat('a')), ['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):
        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(None, 'abc', count())),
                         [('a',0),('b',1),('c',2)])
        self.assertEqual(take(2,imap(None, 'abc', count())),
                         [('a',0),('b',1)])
        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):
        self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
                         [0**1, 1**2, 2**3])
        self.assertEqual(take(3, starmap(operator.pow, izip(count(), count(1)))),
                         [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)
                (10, 20, 3),
                (10, 3, 20),
                (10, 20),
                (10, 3),
                (20,)
                ]:
            self.assertEqual(list(islice(xrange(100), *args)), range(*args))

        for args, tgtargs in [  # Stop when seqn is exhausted
                ((10, 110, 3), ((10, 100, 3))),
                ((10, 110), ((10, 100))),
                ((110,), (100,))
                ]:
            self.assertEqual(list(islice(xrange(100), *args)), range(*tgtargs))

        # Test stop=None
        self.assertEqual(list(islice(xrange(10), None)), range(10))
        self.assertEqual(list(islice(xrange(10), 2, None)), range(2, 10))
        self.assertEqual(list(islice(xrange(10), 1, None, 2)), range(1, 10, 2))

        # Test invalid arguments
        self.assertRaises(TypeError, islice, xrange(10))
        self.assertRaises(TypeError, islice, xrange(10), 1, 2, 3, 4)
        self.assertRaises(ValueError, islice, xrange(10), -5, 10, 1)
        self.assertRaises(ValueError, islice, xrange(10), 1, -5, -1)
        self.assertRaises(ValueError, islice, xrange(10), 1, 10, -1)
        self.assertRaises(ValueError, islice, xrange(10), 1, 10, 0)
        self.assertRaises(ValueError, islice, xrange(10), 'a')
        self.assertRaises(ValueError, islice, xrange(10), 'a', 1)
        self.assertRaises(ValueError, islice, xrange(10), 1, 'a')
        self.assertRaises(ValueError, islice, xrange(10), 'a', 1, 1)
        self.assertRaises(ValueError, islice, xrange(10), 1, 'a', 1)
        self.assertEqual(len(list(islice(count(), 1, 10, sys.maxint))), 1)

    def test_takewhile(self):
        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_tee(self):
        n = 200
        def irange(n):
            for i in xrange(n):
                yield i

        a, b = tee([])        # test empty iterator
        self.assertEqual(list(a), [])
        self.assertEqual(list(b), [])

        a, b = tee(irange(n)) # test 100% interleaved
        self.assertEqual(zip(a,b), zip(range(n),range(n)))

        a, b = tee(irange(n)) # test 0% interleaved
        self.assertEqual(list(a), range(n))
        self.assertEqual(list(b), range(n))

        a, b = tee(irange(n)) # test dealloc of leading iterator
        for i in xrange(100):
            self.assertEqual(a.next(), i)
        del a
        self.assertEqual(list(b), range(n))

        a, b = tee(irange(n)) # test dealloc of trailing iterator
        for i in xrange(100):
            self.assertEqual(a.next(), i)
        del b
        self.assertEqual(list(a), range(100, n))

        for j in xrange(5):   # test randomly interleaved
            order = [0]*n + [1]*n
            random.shuffle(order)
            lists = ([], [])
            its = tee(irange(n))
            for i in order:
                value = its[i].next()
                lists[i].append(value)
            self.assertEqual(lists[0], range(n))
            self.assertEqual(lists[1], range(n))

        # test argument format checking
        self.assertRaises(TypeError, tee)
        self.assertRaises(TypeError, tee, 3)
        self.assertRaises(TypeError, tee, [1,2], 'x')
        self.assertRaises(TypeError, tee, [1,2], 3, 'x')

        # tee object should be instantiable
        a, b = tee('abc')
        c = type(a)('def')
        self.assertEqual(list(c), list('def'))

        # test long-lagged and multi-way split
        a, b, c = tee(xrange(2000), 3)
        for i in xrange(100):
            self.assertEqual(a.next(), i)
        self.assertEqual(list(b), range(2000))
        self.assertEqual([c.next(), c.next()], range(2))
        self.assertEqual(list(a), range(100,2000))
        self.assertEqual(list(c), range(2,2000))

        # tee pass-through to copyable iterator
        a, b = tee('abc')
        c, d = tee(a)
        self.assert_(a is c)


    def test_StopIteration(self):
        self.assertRaises(StopIteration, izip().next)

        for f in (chain, cycle, izip, groupby):
            self.assertRaises(StopIteration, f([]).next)
            self.assertRaises(StopIteration, f(StopNow()).next)

        self.assertRaises(StopIteration, islice([], None).next)
        self.assertRaises(StopIteration, islice(StopNow(), None).next)

        p, q = tee([])
        self.assertRaises(StopIteration, p.next)
        self.assertRaises(StopIteration, q.next)
        p, q = tee(StopNow())
        self.assertRaises(StopIteration, p.next)
        self.assertRaises(StopIteration, q.next)

        self.assertRaises(StopIteration, repeat(None, 0).next)

        for f in (ifilter, ifilterfalse, imap, takewhile, dropwhile, starmap):
            self.assertRaises(StopIteration, f(lambda x:x, []).next)
            self.assertRaises(StopIteration, f(lambda x:x, StopNow()).next)

class TestGC(unittest.TestCase):

    def makecycle(self, iterator, container):
        container.append(iterator)
        iterator.next()
        del container, iterator

    def test_chain(self):
        a = []
        self.makecycle(chain(a), a)

    def test_cycle(self):
        a = []
        self.makecycle(cycle([a]*2), a)

    def test_ifilter(self):
        a = []
        self.makecycle(ifilter(lambda x:True, [a]*2), a)

    def test_ifilterfalse(self):
        a = []
        self.makecycle(ifilterfalse(lambda x:False, a), a)

    def test_izip(self):
        a = []
        self.makecycle(izip([a]*2, [a]*3), a)

    def test_imap(self):
        a = []
        self.makecycle(imap(lambda x:x, [a]*2), a)

    def test_islice(self):
        a = []
        self.makecycle(islice([a]*2, None), a)

    def test_starmap(self):
        a = []
        self.makecycle(starmap(lambda *t: t, [(a,a)]*2), a)

def R(seqn):
    'Regular generator'
    for i in seqn:
        yield i

class G:
    'Sequence using __getitem__'
    def __init__(self, seqn):
        self.seqn = seqn
    def __getitem__(self, i):
        return self.seqn[i]

class I:
    'Sequence using iterator protocol'
    def __init__(self, seqn):
        self.seqn = seqn
        self.i = 0
    def __iter__(self):
        return self
    def next(self):
        if self.i >= len(self.seqn): raise StopIteration
        v = self.seqn[self.i]
        self.i += 1
        return v

class Ig:
    'Sequence using iterator protocol defined with a generator'
    def __init__(self, seqn):
        self.seqn = seqn
        self.i = 0
    def __iter__(self):
        for val in self.seqn:
            yield val

class X:
    'Missing __getitem__ and __iter__'
    def __init__(self, seqn):
        self.seqn = seqn
        self.i = 0
    def next(self):
        if self.i >= len(self.seqn): raise StopIteration
        v = self.seqn[self.i]
        self.i += 1
        return v

class N:
    'Iterator missing next()'
    def __init__(self, seqn):
        self.seqn = seqn
        self.i = 0
    def __iter__(self):
        return self

class E:
    'Test propagation of exceptions'
    def __init__(self, seqn):
        self.seqn = seqn
        self.i = 0
    def __iter__(self):
        return self
    def next(self):
        3/0

class S:
    'Test immediate stop'
    def __init__(self, seqn):
        pass
    def __iter__(self):
        return self
    def next(self):
        raise StopIteration

def L(seqn):
    'Test multiple tiers of iterators'
    return chain(imap(lambda x:x, R(Ig(G(seqn)))))


class TestVariousIteratorArgs(unittest.TestCase):

    def test_chain(self):
        for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(chain(g(s))), list(g(s)))
                self.assertEqual(list(chain(g(s), g(s))), list(g(s))+list(g(s)))
            self.assertRaises(TypeError, chain, X(s))
            self.assertRaises(TypeError, list, chain(N(s)))
            self.assertRaises(ZeroDivisionError, list, chain(E(s)))

    def test_cycle(self):
        for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                tgtlen = len(s) * 3
                expected = list(g(s))*3
                actual = list(islice(cycle(g(s)), tgtlen))
                self.assertEqual(actual, expected)
            self.assertRaises(TypeError, cycle, X(s))
            self.assertRaises(TypeError, list, cycle(N(s)))
            self.assertRaises(ZeroDivisionError, list, cycle(E(s)))

    def test_groupby(self):
        for s in (range(10), range(0), range(1000), (7,11), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual([k for k, sb in groupby(g(s))], list(g(s)))
            self.assertRaises(TypeError, groupby, X(s))
            self.assertRaises(TypeError, list, groupby(N(s)))
            self.assertRaises(ZeroDivisionError, list, groupby(E(s)))

    def test_ifilter(self):
        for s in (range(10), range(0), range(1000), (7,11), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(ifilter(isEven, g(s))), filter(isEven, g(s)))
            self.assertRaises(TypeError, ifilter, isEven, X(s))
            self.assertRaises(TypeError, list, ifilter(isEven, N(s)))
            self.assertRaises(ZeroDivisionError, list, ifilter(isEven, E(s)))

    def test_ifilterfalse(self):
        for s in (range(10), range(0), range(1000), (7,11), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(ifilterfalse(isEven, g(s))), filter(isOdd, g(s)))
            self.assertRaises(TypeError, ifilterfalse, isEven, X(s))
            self.assertRaises(TypeError, list, ifilterfalse(isEven, N(s)))
            self.assertRaises(ZeroDivisionError, list, ifilterfalse(isEven, E(s)))

    def test_izip(self):
        for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(izip(g(s))), zip(g(s)))
                self.assertEqual(list(izip(g(s), g(s))), zip(g(s), g(s)))
            self.assertRaises(TypeError, izip, X(s))
            self.assertRaises(TypeError, list, izip(N(s)))
            self.assertRaises(ZeroDivisionError, list, izip(E(s)))

    def test_imap(self):
        for s in (range(10), range(0), range(100), (7,11), xrange(20,50,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(imap(onearg, g(s))), map(onearg, g(s)))
                self.assertEqual(list(imap(operator.pow, g(s), g(s))), map(operator.pow, g(s), g(s)))
            self.assertRaises(TypeError, imap, onearg, X(s))
            self.assertRaises(TypeError, list, imap(onearg, N(s)))
            self.assertRaises(ZeroDivisionError, list, imap(onearg, E(s)))

    def test_islice(self):
        for s in ("12345", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                self.assertEqual(list(islice(g(s),1,None,2)), list(g(s))[1::2])
            self.assertRaises(TypeError, islice, X(s), 10)
            self.assertRaises(TypeError, list, islice(N(s), 10))
            self.assertRaises(ZeroDivisionError, list, islice(E(s), 10))

    def test_starmap(self):
        for s in (range(10), range(0), range(100), (7,11), xrange(20,50,5)):
            for g in (G, I, Ig, S, L, R):
                ss = zip(s, s)
                self.assertEqual(list(starmap(operator.pow, g(ss))), map(operator.pow, g(s), g(s)))
            self.assertRaises(TypeError, starmap, operator.pow, X(ss))
            self.assertRaises(TypeError, list, starmap(operator.pow, N(ss)))
            self.assertRaises(ZeroDivisionError, list, starmap(operator.pow, E(ss)))

    def test_takewhile(self):
        for s in (range(10), range(0), range(1000), (7,11), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                tgt = []
                for elem in g(s):
                    if not isEven(elem): break
                    tgt.append(elem)
                self.assertEqual(list(takewhile(isEven, g(s))), tgt)
            self.assertRaises(TypeError, takewhile, isEven, X(s))
            self.assertRaises(TypeError, list, takewhile(isEven, N(s)))
            self.assertRaises(ZeroDivisionError, list, takewhile(isEven, E(s)))

    def test_dropwhile(self):
        for s in (range(10), range(0), range(1000), (7,11), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                tgt = []
                for elem in g(s):
                    if not tgt and isOdd(elem): continue
                    tgt.append(elem)
                self.assertEqual(list(dropwhile(isOdd, g(s))), tgt)
            self.assertRaises(TypeError, dropwhile, isOdd, X(s))
            self.assertRaises(TypeError, list, dropwhile(isOdd, N(s)))
            self.assertRaises(ZeroDivisionError, list, dropwhile(isOdd, E(s)))

    def test_tee(self):
        for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
            for g in (G, I, Ig, S, L, R):
                it1, it2 = tee(g(s))
                self.assertEqual(list(it1), list(g(s)))
                self.assertEqual(list(it2), list(g(s)))
            self.assertRaises(TypeError, tee, X(s))
            self.assertRaises(TypeError, list, tee(N(s))[0])
            self.assertRaises(ZeroDivisionError, list, tee(E(s))[0])

class LengthTransparency(unittest.TestCase):

    def test_repeat(self):
        self.assertEqual(len(repeat(None, 50)), 50)
        self.assertRaises(TypeError, len, repeat(None))

class RegressionTests(unittest.TestCase):

    def test_sf_793826(self):
        # Fix Armin Rigo's successful efforts to wreak havoc

        def mutatingtuple(tuple1, f, tuple2):
            # this builds a tuple t which is a copy of tuple1,
            # then calls f(t), then mutates t to be equal to tuple2
            # (needs len(tuple1) == len(tuple2)).
            def g(value, first=[1]):
                if first:
                    del first[:]
                    f(z.next())
                return value
            items = list(tuple2)
            items[1:1] = list(tuple1)
            gen = imap(g, items)
            z = izip(*[gen]*len(tuple1))
            z.next()

        def f(t):
            global T
            T = t
            first[:] = list(T)

        first = []
        mutatingtuple((1,2,3), f, (4,5,6))
        second = list(T)
        self.assertEqual(first, second)


libreftest = """ Doctest for examples in the library reference: libitertools.tex


>>> amounts = [120.15, 764.05, 823.14]
>>> for checknum, amount in izip(count(1200), amounts):
...     print 'Check %d is for $%.2f' % (checknum, amount)
...
Check 1200 is for $120.15
Check 1201 is for $764.05
Check 1202 is for $823.14

>>> import operator
>>> for cube in imap(operator.pow, xrange(1,4), repeat(3)):
...    print cube
...
1
8
27

>>> reportlines = ['EuroPython', 'Roster', '', 'alex', '', 'laura', '', 'martin', '', 'walter', '', 'samuele']
>>> for name in islice(reportlines, 3, None, 2):
...    print name.title()
...
Alex
Laura
Martin
Walter
Samuele

>>> from operator import itemgetter
>>> d = dict(a=1, b=2, c=1, d=2, e=1, f=2, g=3)
>>> di = sorted(d.iteritems(), key=itemgetter(1))
>>> for k, g in groupby(di, itemgetter(1)):
...     print k, map(itemgetter(0), g)
...
1 ['a', 'c', 'e']
2 ['b', 'd', 'f']
3 ['g']

# Find runs of consecutive numbers using groupby.  The key to the solution
# is differencing with a range so that consecutive numbers all appear in
# same group.
>>> data = [ 1,  4,5,6, 10, 15,16,17,18, 22, 25,26,27,28]
>>> for k, g in groupby(enumerate(data), lambda (i,x):i-x):
...     print map(operator.itemgetter(1), g)
...
[1]
[4, 5, 6]
[10]
[15, 16, 17, 18]
[22]
[25, 26, 27, 28]

>>> def take(n, seq):
...     return list(islice(seq, n))

>>> def enumerate(iterable):
...     return izip(count(), iterable)

>>> def tabulate(function):
...     "Return function(0), function(1), ..."
...     return imap(function, count())

>>> def iteritems(mapping):
...     return izip(mapping.iterkeys(), mapping.itervalues())

>>> def nth(iterable, n):
...     "Returns the nth item"
...     return list(islice(iterable, n, n+1))

>>> def all(seq, pred=bool):
...     "Returns True if pred(x) is True for every element in the iterable"
...     return False not in imap(pred, seq)

>>> def any(seq, pred=bool):
...     "Returns True if pred(x) is True for at least one element in the iterable"
...     return True in imap(pred, seq)

>>> def no(seq, pred=bool):
...     "Returns True if pred(x) is False for every element in the iterable"
...     return True not in imap(pred, seq)

>>> def quantify(seq, pred=bool):
...     "Count how many times the predicate is True in the sequence"
...     return sum(imap(pred, seq))

>>> def padnone(seq):
...     "Returns the sequence elements and then returns None indefinitely"
...     return chain(seq, repeat(None))

>>> def ncycles(seq, n):
...     "Returns the sequence elements n times"
...     return chain(*repeat(seq, n))

>>> def dotproduct(vec1, vec2):
...     return sum(imap(operator.mul, vec1, vec2))

>>> def flatten(listOfLists):
...     return list(chain(*listOfLists))

>>> def repeatfunc(func, times=None, *args):
...     "Repeat calls to func with specified arguments."
...     "   Example:  repeatfunc(random.random)"
...     if times is None:
...         return starmap(func, repeat(args))
...     else:
...         return starmap(func, repeat(args, times))

>>> def pairwise(iterable):
...     "s -> (s0,s1), (s1,s2), (s2, s3), ..."
...     a, b = tee(iterable)
...     try:
...         b.next()
...     except StopIteration:
...         pass
...     return izip(a, b)

This is not part of the examples but it tests to make sure the definitions
perform as purported.

>>> take(10, count())
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> list(enumerate('abc'))
[(0, 'a'), (1, 'b'), (2, 'c')]

>>> list(islice(tabulate(lambda x: 2*x), 4))
[0, 2, 4, 6]

>>> nth('abcde', 3)
['d']

>>> all([2, 4, 6, 8], lambda x: x%2==0)
True

>>> all([2, 3, 6, 8], lambda x: x%2==0)
False

>>> any([2, 4, 6, 8], lambda x: x%2==0)
True

>>> any([1, 3, 5, 9], lambda x: x%2==0,)
False

>>> no([1, 3, 5, 9], lambda x: x%2==0)
True

>>> no([1, 2, 5, 9], lambda x: x%2==0)
False

>>> quantify(xrange(99), lambda x: x%2==0)
50

>>> a = [[1, 2, 3], [4, 5, 6]]
>>> flatten(a)
[1, 2, 3, 4, 5, 6]

>>> list(repeatfunc(pow, 5, 2, 3))
[8, 8, 8, 8, 8]

>>> import random
>>> take(5, imap(int, repeatfunc(random.random)))
[0, 0, 0, 0, 0]

>>> list(pairwise('abcd'))
[('a', 'b'), ('b', 'c'), ('c', 'd')]

>>> list(pairwise([]))
[]

>>> list(pairwise('a'))
[]

>>> list(islice(padnone('abc'), 0, 6))
['a', 'b', 'c', None, None, None]

>>> list(ncycles('abc', 3))
['a', 'b', 'c', 'a', 'b', 'c', 'a', 'b', 'c']

>>> dotproduct([1,2,3], [4,5,6])
32

"""

__test__ = {'libreftest' : libreftest}

def test_main(verbose=None):
    test_classes = (TestBasicOps, TestVariousIteratorArgs, TestGC,
                    RegressionTests, LengthTransparency)
    test_support.run_unittest(*test_classes)

    # verify reference counting
    if verbose and hasattr(sys, "gettotalrefcount"):
        import gc
        counts = [None] * 5
        for i in xrange(len(counts)):
            test_support.run_unittest(*test_classes)
            gc.collect()
            counts[i] = sys.gettotalrefcount()
        print counts

    # doctest the examples in the library reference
    test_support.run_doctest(sys.modules[__name__], verbose)

if __name__ == "__main__":
    test_main(verbose=True)