summaryrefslogtreecommitdiffstats
path: root/Lib/test/test_iter.py
blob: 820911da35ab0397c4d66291465f15aca20e1d61 (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
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
# Test iterators.

import unittest
from test.test_support import run_unittest, TESTFN, unlink, have_unicode

# Test result of triple loop (too big to inline)
TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
            (0, 1, 0), (0, 1, 1), (0, 1, 2),
            (0, 2, 0), (0, 2, 1), (0, 2, 2),

            (1, 0, 0), (1, 0, 1), (1, 0, 2),
            (1, 1, 0), (1, 1, 1), (1, 1, 2),
            (1, 2, 0), (1, 2, 1), (1, 2, 2),

            (2, 0, 0), (2, 0, 1), (2, 0, 2),
            (2, 1, 0), (2, 1, 1), (2, 1, 2),
            (2, 2, 0), (2, 2, 1), (2, 2, 2)]

# Helper classes

class BasicIterClass:
    def __init__(self, n):
        self.n = n
        self.i = 0
    def next(self):
        res = self.i
        if res >= self.n:
            raise StopIteration
        self.i = res + 1
        return res

class IteratingSequenceClass:
    def __init__(self, n):
        self.n = n
    def __iter__(self):
        return BasicIterClass(self.n)

class SequenceClass:
    def __init__(self, n):
        self.n = n
    def __getitem__(self, i):
        if 0 <= i < self.n:
            return i
        else:
            raise IndexError

# Main test suite

class TestCase(unittest.TestCase):

    # Helper to check that an iterator returns a given sequence
    def check_iterator(self, it, seq):
        res = []
        while 1:
            try:
                val = it.next()
            except StopIteration:
                break
            res.append(val)
        self.assertEqual(res, seq)

    # Helper to check that a for loop generates a given sequence
    def check_for_loop(self, expr, seq):
        res = []
        for val in expr:
            res.append(val)
        self.assertEqual(res, seq)

    # Test basic use of iter() function
    def test_iter_basic(self):
        self.check_iterator(iter(range(10)), range(10))

    # Test that iter(iter(x)) is the same as iter(x)
    def test_iter_idempotency(self):
        seq = range(10)
        it = iter(seq)
        it2 = iter(it)
        self.assert_(it is it2)

    # Test that for loops over iterators work
    def test_iter_for_loop(self):
        self.check_for_loop(iter(range(10)), range(10))

    # Test several independent iterators over the same list
    def test_iter_independence(self):
        seq = range(3)
        res = []
        for i in iter(seq):
            for j in iter(seq):
                for k in iter(seq):
                    res.append((i, j, k))
        self.assertEqual(res, TRIPLETS)

    # Test triple list comprehension using iterators
    def test_nested_comprehensions_iter(self):
        seq = range(3)
        res = [(i, j, k)
               for i in iter(seq) for j in iter(seq) for k in iter(seq)]
        self.assertEqual(res, TRIPLETS)

    # Test triple list comprehension without iterators
    def test_nested_comprehensions_for(self):
        seq = range(3)
        res = [(i, j, k) for i in seq for j in seq for k in seq]
        self.assertEqual(res, TRIPLETS)

    # Test a class with __iter__ in a for loop
    def test_iter_class_for(self):
        self.check_for_loop(IteratingSequenceClass(10), range(10))

    # Test a class with __iter__ with explicit iter()
    def test_iter_class_iter(self):
        self.check_iterator(iter(IteratingSequenceClass(10)), range(10))

    # Test for loop on a sequence class without __iter__
    def test_seq_class_for(self):
        self.check_for_loop(SequenceClass(10), range(10))

    # Test iter() on a sequence class without __iter__
    def test_seq_class_iter(self):
        self.check_iterator(iter(SequenceClass(10)), range(10))

    # Test two-argument iter() with callable instance
    def test_iter_callable(self):
        class C:
            def __init__(self):
                self.i = 0
            def __call__(self):
                i = self.i
                self.i = i + 1
                if i > 100:
                    raise IndexError # Emergency stop
                return i
        self.check_iterator(iter(C(), 10), range(10))

    # Test two-argument iter() with function
    def test_iter_function(self):
        def spam(state=[0]):
            i = state[0]
            state[0] = i+1
            return i
        self.check_iterator(iter(spam, 10), range(10))

    # Test two-argument iter() with function that raises StopIteration
    def test_iter_function_stop(self):
        def spam(state=[0]):
            i = state[0]
            if i == 10:
                raise StopIteration
            state[0] = i+1
            return i
        self.check_iterator(iter(spam, 20), range(10))

    # Test exception propagation through function iterator
    def test_exception_function(self):
        def spam(state=[0]):
            i = state[0]
            state[0] = i+1
            if i == 10:
                raise RuntimeError
            return i
        res = []
        try:
            for x in iter(spam, 20):
                res.append(x)
        except RuntimeError:
            self.assertEqual(res, range(10))
        else:
            self.fail("should have raised RuntimeError")

    # Test exception propagation through sequence iterator
    def test_exception_sequence(self):
        class MySequenceClass(SequenceClass):
            def __getitem__(self, i):
                if i == 10:
                    raise RuntimeError
                return SequenceClass.__getitem__(self, i)
        res = []
        try:
            for x in MySequenceClass(20):
                res.append(x)
        except RuntimeError:
            self.assertEqual(res, range(10))
        else:
            self.fail("should have raised RuntimeError")

    # Test for StopIteration from __getitem__
    def test_stop_sequence(self):
        class MySequenceClass(SequenceClass):
            def __getitem__(self, i):
                if i == 10:
                    raise StopIteration
                return SequenceClass.__getitem__(self, i)
        self.check_for_loop(MySequenceClass(20), range(10))

    # Test a big range
    def test_iter_big_range(self):
        self.check_for_loop(iter(range(10000)), range(10000))

    # Test an empty list
    def test_iter_empty(self):
        self.check_for_loop(iter([]), [])

    # Test a tuple
    def test_iter_tuple(self):
        self.check_for_loop(iter((0,1,2,3,4,5,6,7,8,9)), range(10))

    # Test an xrange
    def test_iter_xrange(self):
        self.check_for_loop(iter(xrange(10)), range(10))

    # Test a string
    def test_iter_string(self):
        self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"])

    # Test a Unicode string
    if have_unicode:
        def test_iter_unicode(self):
            self.check_for_loop(iter(unicode("abcde")),
                                [unicode("a"), unicode("b"), unicode("c"),
                                 unicode("d"), unicode("e")])

    # Test a directory
    def test_iter_dict(self):
        dict = {}
        for i in range(10):
            dict[i] = None
        self.check_for_loop(dict, list(dict.keys()))

    # Test a file
    def test_iter_file(self):
        f = open(TESTFN, "w")
        try:
            for i in range(5):
                f.write("%d\n" % i)
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
            self.check_for_loop(f, [])
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test list()'s use of iterators.
    def test_builtin_list(self):
        self.assertEqual(list(SequenceClass(5)), range(5))
        self.assertEqual(list(SequenceClass(0)), [])
        self.assertEqual(list(()), [])
        self.assertEqual(list(range(10, -1, -1)), range(10, -1, -1))

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(list(d), list(d.keys()))

        self.assertRaises(TypeError, list, list)
        self.assertRaises(TypeError, list, 42)

        f = open(TESTFN, "w")
        try:
            for i in range(5):
                f.write("%d\n" % i)
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.assertEqual(list(f), ["0\n", "1\n", "2\n", "3\n", "4\n"])
            f.seek(0, 0)
            self.assertEqual(list(f),
                             ["0\n", "1\n", "2\n", "3\n", "4\n"])
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test tuples()'s use of iterators.
    def test_builtin_tuple(self):
        self.assertEqual(tuple(SequenceClass(5)), (0, 1, 2, 3, 4))
        self.assertEqual(tuple(SequenceClass(0)), ())
        self.assertEqual(tuple([]), ())
        self.assertEqual(tuple(()), ())
        self.assertEqual(tuple("abc"), ("a", "b", "c"))

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(tuple(d), tuple(d.keys()))

        self.assertRaises(TypeError, tuple, list)
        self.assertRaises(TypeError, tuple, 42)

        f = open(TESTFN, "w")
        try:
            for i in range(5):
                f.write("%d\n" % i)
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.assertEqual(tuple(f), ("0\n", "1\n", "2\n", "3\n", "4\n"))
            f.seek(0, 0)
            self.assertEqual(tuple(f),
                             ("0\n", "1\n", "2\n", "3\n", "4\n"))
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test filter()'s use of iterators.
    def test_builtin_filter(self):
        self.assertEqual(filter(None, SequenceClass(5)), range(1, 5))
        self.assertEqual(filter(None, SequenceClass(0)), [])
        self.assertEqual(filter(None, ()), ())
        self.assertEqual(filter(None, "abc"), "abc")

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(filter(None, d), list(d.keys()))

        self.assertRaises(TypeError, filter, None, list)
        self.assertRaises(TypeError, filter, None, 42)

        class Boolean:
            def __init__(self, truth):
                self.truth = truth
            def __bool__(self):
                return self.truth
        bTrue = Boolean(True)
        bFalse = Boolean(False)

        class Seq:
            def __init__(self, *args):
                self.vals = args
            def __iter__(self):
                class SeqIter:
                    def __init__(self, vals):
                        self.vals = vals
                        self.i = 0
                    def __iter__(self):
                        return self
                    def next(self):
                        i = self.i
                        self.i = i + 1
                        if i < len(self.vals):
                            return self.vals[i]
                        else:
                            raise StopIteration
                return SeqIter(self.vals)

        seq = Seq(*([bTrue, bFalse] * 25))
        self.assertEqual(filter(lambda x: not x, seq), [bFalse]*25)
        self.assertEqual(filter(lambda x: not x, iter(seq)), [bFalse]*25)

    # Test max() and min()'s use of iterators.
    def test_builtin_max_min(self):
        self.assertEqual(max(SequenceClass(5)), 4)
        self.assertEqual(min(SequenceClass(5)), 0)
        self.assertEqual(max(8, -1), 8)
        self.assertEqual(min(8, -1), -1)

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(max(d), "two")
        self.assertEqual(min(d), "one")
        self.assertEqual(max(d.values()), 3)
        self.assertEqual(min(iter(d.values())), 1)

        f = open(TESTFN, "w")
        try:
            f.write("medium line\n")
            f.write("xtra large line\n")
            f.write("itty-bitty line\n")
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.assertEqual(min(f), "itty-bitty line\n")
            f.seek(0, 0)
            self.assertEqual(max(f), "xtra large line\n")
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test map()'s use of iterators.
    def test_builtin_map(self):
        self.assertEqual(map(None, SequenceClass(5)), range(5))
        self.assertEqual(map(lambda x: x+1, SequenceClass(5)), range(1, 6))

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(map(None, d), list(d.keys()))
        self.assertEqual(map(lambda k, d=d: (k, d[k]), d), list(d.items()))
        dkeys = list(d.keys())
        expected = [(i < len(d) and dkeys[i] or None,
                     i,
                     i < len(d) and dkeys[i] or None)
                    for i in range(5)]
        self.assertEqual(map(None, d,
                                   SequenceClass(5),
                                   iter(d.keys())),
                         expected)

        f = open(TESTFN, "w")
        try:
            for i in range(10):
                f.write("xy" * i + "\n") # line i has len 2*i+1
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.assertEqual(map(len, f), range(1, 21, 2))
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test zip()'s use of iterators.
    def test_builtin_zip(self):
        self.assertEqual(list(zip()), [])
        self.assertEqual(list(zip(*[])), [])
        self.assertEqual(list(zip(*[(1, 2), 'ab'])), [(1, 'a'), (2, 'b')])

        self.assertRaises(TypeError, zip, None)
        self.assertRaises(TypeError, zip, range(10), 42)
        self.assertRaises(TypeError, zip, range(10), zip)

        self.assertEqual(list(zip(IteratingSequenceClass(3))),
                         [(0,), (1,), (2,)])
        self.assertEqual(list(zip(SequenceClass(3))),
                         [(0,), (1,), (2,)])

        d = {"one": 1, "two": 2, "three": 3}
        self.assertEqual(list(d.items()), list(zip(d, d.values())))

        # Generate all ints starting at constructor arg.
        class IntsFrom:
            def __init__(self, start):
                self.i = start

            def __iter__(self):
                return self

            def next(self):
                i = self.i
                self.i = i+1
                return i

        f = open(TESTFN, "w")
        try:
            f.write("a\n" "bbb\n" "cc\n")
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            self.assertEqual(list(zip(IntsFrom(0), f, IntsFrom(-100))),
                             [(0, "a\n", -100),
                              (1, "bbb\n", -99),
                              (2, "cc\n", -98)])
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

        self.assertEqual(list(zip(xrange(5))), [(i,) for i in range(5)])

        # Classes that lie about their lengths.
        class NoGuessLen5:
            def __getitem__(self, i):
                if i >= 5:
                    raise IndexError
                return i

        class Guess3Len5(NoGuessLen5):
            def __len__(self):
                return 3

        class Guess30Len5(NoGuessLen5):
            def __len__(self):
                return 30

        def lzip(*args):
            return list(zip(*args))

        self.assertEqual(len(Guess3Len5()), 3)
        self.assertEqual(len(Guess30Len5()), 30)
        self.assertEqual(lzip(NoGuessLen5()), lzip(range(5)))
        self.assertEqual(lzip(Guess3Len5()), lzip(range(5)))
        self.assertEqual(lzip(Guess30Len5()), lzip(range(5)))

        expected = [(i, i) for i in range(5)]
        for x in NoGuessLen5(), Guess3Len5(), Guess30Len5():
            for y in NoGuessLen5(), Guess3Len5(), Guess30Len5():
                self.assertEqual(lzip(x, y), expected)

    # This test case will be removed if we don't have Unicode
    def test_unicode_join_endcase(self):

        # This class inserts a Unicode object into its argument's natural
        # iteration, in the 3rd position.
        class OhPhooey:
            def __init__(self, seq):
                self.it = iter(seq)
                self.i = 0

            def __iter__(self):
                return self

            def next(self):
                i = self.i
                self.i = i+1
                if i == 2:
                    return unicode("fooled you!")
                return self.it.next()

        f = open(TESTFN, "w")
        try:
            f.write("a\n" + "b\n" + "c\n")
        finally:
            f.close()

        f = open(TESTFN, "r")
        # Nasty:  string.join(s) can't know whether unicode.join() is needed
        # until it's seen all of s's elements.  But in this case, f's
        # iterator cannot be restarted.  So what we're testing here is
        # whether string.join() can manage to remember everything it's seen
        # and pass that on to unicode.join().
        try:
            got = " - ".join(OhPhooey(f))
            self.assertEqual(got, unicode("a\n - b\n - fooled you! - c\n"))
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass
    if not have_unicode:
        def test_unicode_join_endcase(self): pass

    # Test iterators with 'x in y' and 'x not in y'.
    def test_in_and_not_in(self):
        for sc5 in IteratingSequenceClass(5), SequenceClass(5):
            for i in range(5):
                self.assert_(i in sc5)
            for i in "abc", -1, 5, 42.42, (3, 4), [], {1: 1}, 3-12j, sc5:
                self.assert_(i not in sc5)

        self.assertRaises(TypeError, lambda: 3 in 12)
        self.assertRaises(TypeError, lambda: 3 not in map)

        d = {"one": 1, "two": 2, "three": 3, 1j: 2j}
        for k in d:
            self.assert_(k in d)
            self.assert_(k not in d.values())
        for v in d.values():
            self.assert_(v in d.values())
            self.assert_(v not in d)
        for k, v in d.items():
            self.assert_((k, v) in d.items())
            self.assert_((v, k) not in d.items())

        f = open(TESTFN, "w")
        try:
            f.write("a\n" "b\n" "c\n")
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            for chunk in "abc":
                f.seek(0, 0)
                self.assert_(chunk not in f)
                f.seek(0, 0)
                self.assert_((chunk + "\n") in f)
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test iterators with operator.countOf (PySequence_Count).
    def test_countOf(self):
        from operator import countOf
        self.assertEqual(countOf([1,2,2,3,2,5], 2), 3)
        self.assertEqual(countOf((1,2,2,3,2,5), 2), 3)
        self.assertEqual(countOf("122325", "2"), 3)
        self.assertEqual(countOf("122325", "6"), 0)

        self.assertRaises(TypeError, countOf, 42, 1)
        self.assertRaises(TypeError, countOf, countOf, countOf)

        d = {"one": 3, "two": 3, "three": 3, 1j: 2j}
        for k in d:
            self.assertEqual(countOf(d, k), 1)
        self.assertEqual(countOf(d.values(), 3), 3)
        self.assertEqual(countOf(d.values(), 2j), 1)
        self.assertEqual(countOf(d.values(), 1j), 0)

        f = open(TESTFN, "w")
        try:
            f.write("a\n" "b\n" "c\n" "b\n")
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            for letter, count in ("a", 1), ("b", 2), ("c", 1), ("d", 0):
                f.seek(0, 0)
                self.assertEqual(countOf(f, letter + "\n"), count)
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

    # Test iterators with operator.indexOf (PySequence_Index).
    def test_indexOf(self):
        from operator import indexOf
        self.assertEqual(indexOf([1,2,2,3,2,5], 1), 0)
        self.assertEqual(indexOf((1,2,2,3,2,5), 2), 1)
        self.assertEqual(indexOf((1,2,2,3,2,5), 3), 3)
        self.assertEqual(indexOf((1,2,2,3,2,5), 5), 5)
        self.assertRaises(ValueError, indexOf, (1,2,2,3,2,5), 0)
        self.assertRaises(ValueError, indexOf, (1,2,2,3,2,5), 6)

        self.assertEqual(indexOf("122325", "2"), 1)
        self.assertEqual(indexOf("122325", "5"), 5)
        self.assertRaises(ValueError, indexOf, "122325", "6")

        self.assertRaises(TypeError, indexOf, 42, 1)
        self.assertRaises(TypeError, indexOf, indexOf, indexOf)

        f = open(TESTFN, "w")
        try:
            f.write("a\n" "b\n" "c\n" "d\n" "e\n")
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            fiter = iter(f)
            self.assertEqual(indexOf(fiter, "b\n"), 1)
            self.assertEqual(indexOf(fiter, "d\n"), 1)
            self.assertEqual(indexOf(fiter, "e\n"), 0)
            self.assertRaises(ValueError, indexOf, fiter, "a\n")
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

        iclass = IteratingSequenceClass(3)
        for i in range(3):
            self.assertEqual(indexOf(iclass, i), i)
        self.assertRaises(ValueError, indexOf, iclass, -1)

    # Test iterators with file.writelines().
    def test_writelines(self):
        f = open(TESTFN, "w")

        try:
            self.assertRaises(TypeError, f.writelines, None)
            self.assertRaises(TypeError, f.writelines, 42)

            f.writelines(["1\n", "2\n"])
            f.writelines(("3\n", "4\n"))
            f.writelines({'5\n': None})
            f.writelines({})

            # Try a big chunk too.
            class Iterator:
                def __init__(self, start, finish):
                    self.start = start
                    self.finish = finish
                    self.i = self.start

                def next(self):
                    if self.i >= self.finish:
                        raise StopIteration
                    result = str(self.i) + '\n'
                    self.i += 1
                    return result

                def __iter__(self):
                    return self

            class Whatever:
                def __init__(self, start, finish):
                    self.start = start
                    self.finish = finish

                def __iter__(self):
                    return Iterator(self.start, self.finish)

            f.writelines(Whatever(6, 6+2000))
            f.close()

            f = open(TESTFN)
            expected = [str(i) + "\n" for i in range(1, 2006)]
            self.assertEqual(list(f), expected)

        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass


    # Test iterators on RHS of unpacking assignments.
    def test_unpack_iter(self):
        a, b = 1, 2
        self.assertEqual((a, b), (1, 2))

        a, b, c = IteratingSequenceClass(3)
        self.assertEqual((a, b, c), (0, 1, 2))

        try:    # too many values
            a, b = IteratingSequenceClass(3)
        except ValueError:
            pass
        else:
            self.fail("should have raised ValueError")

        try:    # not enough values
            a, b, c = IteratingSequenceClass(2)
        except ValueError:
            pass
        else:
            self.fail("should have raised ValueError")

        try:    # not iterable
            a, b, c = len
        except TypeError:
            pass
        else:
            self.fail("should have raised TypeError")

        a, b, c = {1: 42, 2: 42, 3: 42}.values()
        self.assertEqual((a, b, c), (42, 42, 42))

        f = open(TESTFN, "w")
        lines = ("a\n", "bb\n", "ccc\n")
        try:
            for line in lines:
                f.write(line)
        finally:
            f.close()
        f = open(TESTFN, "r")
        try:
            a, b, c = f
            self.assertEqual((a, b, c), lines)
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

        (a, b), (c,) = IteratingSequenceClass(2), {42: 24}
        self.assertEqual((a, b, c), (0, 1, 42))

        # Test reference count behavior

        class C(object):
            count = 0
            def __new__(cls):
                cls.count += 1
                return object.__new__(cls)
            def __del__(self):
                cls = self.__class__
                assert cls.count > 0
                cls.count -= 1
        x = C()
        self.assertEqual(C.count, 1)
        del x
        self.assertEqual(C.count, 0)
        l = [C(), C(), C()]
        self.assertEqual(C.count, 3)
        try:
            a, b = iter(l)
        except ValueError:
            pass
        del l
        self.assertEqual(C.count, 0)


    # Make sure StopIteration is a "sink state".
    # This tests various things that weren't sink states in Python 2.2.1,
    # plus various things that always were fine.

    def test_sinkstate_list(self):
        # This used to fail
        a = range(5)
        b = iter(a)
        self.assertEqual(list(b), range(5))
        a.extend(range(5, 10))
        self.assertEqual(list(b), [])

    def test_sinkstate_tuple(self):
        a = (0, 1, 2, 3, 4)
        b = iter(a)
        self.assertEqual(list(b), range(5))
        self.assertEqual(list(b), [])

    def test_sinkstate_string(self):
        a = "abcde"
        b = iter(a)
        self.assertEqual(list(b), ['a', 'b', 'c', 'd', 'e'])
        self.assertEqual(list(b), [])

    def test_sinkstate_sequence(self):
        # This used to fail
        a = SequenceClass(5)
        b = iter(a)
        self.assertEqual(list(b), range(5))
        a.n = 10
        self.assertEqual(list(b), [])

    def test_sinkstate_callable(self):
        # This used to fail
        def spam(state=[0]):
            i = state[0]
            state[0] = i+1
            if i == 10:
                raise AssertionError, "shouldn't have gotten this far"
            return i
        b = iter(spam, 5)
        self.assertEqual(list(b), range(5))
        self.assertEqual(list(b), [])

    def test_sinkstate_dict(self):
        # XXX For a more thorough test, see towards the end of:
        # http://mail.python.org/pipermail/python-dev/2002-July/026512.html
        a = {1:1, 2:2, 0:0, 4:4, 3:3}
        for b in iter(a), a.keys(), a.items(), a.values():
            b = iter(a)
            self.assertEqual(len(list(b)), 5)
            self.assertEqual(list(b), [])

    def test_sinkstate_yield(self):
        def gen():
            for i in range(5):
                yield i
        b = gen()
        self.assertEqual(list(b), range(5))
        self.assertEqual(list(b), [])

    def test_sinkstate_range(self):
        a = xrange(5)
        b = iter(a)
        self.assertEqual(list(b), range(5))
        self.assertEqual(list(b), [])

    def test_sinkstate_enumerate(self):
        a = range(5)
        e = enumerate(a)
        b = iter(e)
        self.assertEqual(list(b), list(zip(range(5), range(5))))
        self.assertEqual(list(b), [])


def test_main():
    run_unittest(TestCase)


if __name__ == "__main__":
    test_main()