This file is indexed.

/usr/lib/python3.7/test/test_capi.py is in libpython3.7-testsuite 3.7.0~b3-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
# Run the _testcapi module tests (tests for the Python/C API):  by defn,
# these are all functions _testcapi exports whose name begins with 'test_'.

from collections import OrderedDict
import os
import pickle
import random
import re
import subprocess
import sys
import sysconfig
import textwrap
import threading
import time
import unittest
from test import support
from test.support import MISSING_C_DOCSTRINGS
from test.support.script_helper import assert_python_failure, assert_python_ok
try:
    import _posixsubprocess
except ImportError:
    _posixsubprocess = None

# Skip this test if the _testcapi module isn't available.
_testcapi = support.import_module('_testcapi')

# Were we compiled --with-pydebug or with #define Py_DEBUG?
Py_DEBUG = hasattr(sys, 'gettotalrefcount')


def testfunction(self):
    """some doc"""
    return self

class InstanceMethod:
    id = _testcapi.instancemethod(id)
    testfunction = _testcapi.instancemethod(testfunction)

class CAPITest(unittest.TestCase):

    def test_instancemethod(self):
        inst = InstanceMethod()
        self.assertEqual(id(inst), inst.id())
        self.assertTrue(inst.testfunction() is inst)
        self.assertEqual(inst.testfunction.__doc__, testfunction.__doc__)
        self.assertEqual(InstanceMethod.testfunction.__doc__, testfunction.__doc__)

        InstanceMethod.testfunction.attribute = "test"
        self.assertEqual(testfunction.attribute, "test")
        self.assertRaises(AttributeError, setattr, inst.testfunction, "attribute", "test")

    def test_no_FatalError_infinite_loop(self):
        with support.SuppressCrashReport():
            p = subprocess.Popen([sys.executable, "-c",
                                  'import _testcapi;'
                                  '_testcapi.crash_no_current_thread()'],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE)
        (out, err) = p.communicate()
        self.assertEqual(out, b'')
        # This used to cause an infinite loop.
        self.assertTrue(err.rstrip().startswith(
                         b'Fatal Python error:'
                         b' PyThreadState_Get: no current thread'))

    def test_memoryview_from_NULL_pointer(self):
        self.assertRaises(ValueError, _testcapi.make_memoryview_from_NULL_pointer)

    def test_exc_info(self):
        raised_exception = ValueError("5")
        new_exc = TypeError("TEST")
        try:
            raise raised_exception
        except ValueError as e:
            tb = e.__traceback__
            orig_sys_exc_info = sys.exc_info()
            orig_exc_info = _testcapi.set_exc_info(new_exc.__class__, new_exc, None)
            new_sys_exc_info = sys.exc_info()
            new_exc_info = _testcapi.set_exc_info(*orig_exc_info)
            reset_sys_exc_info = sys.exc_info()

            self.assertEqual(orig_exc_info[1], e)

            self.assertSequenceEqual(orig_exc_info, (raised_exception.__class__, raised_exception, tb))
            self.assertSequenceEqual(orig_sys_exc_info, orig_exc_info)
            self.assertSequenceEqual(reset_sys_exc_info, orig_exc_info)
            self.assertSequenceEqual(new_exc_info, (new_exc.__class__, new_exc, None))
            self.assertSequenceEqual(new_sys_exc_info, new_exc_info)
        else:
            self.assertTrue(False)

    @unittest.skipUnless(_posixsubprocess, '_posixsubprocess required for this test.')
    def test_seq_bytes_to_charp_array(self):
        # Issue #15732: crash in _PySequence_BytesToCharpArray()
        class Z(object):
            def __len__(self):
                return 1
        self.assertRaises(TypeError, _posixsubprocess.fork_exec,
                          1,Z(),3,(1, 2),5,6,7,8,9,10,11,12,13,14,15,16,17)
        # Issue #15736: overflow in _PySequence_BytesToCharpArray()
        class Z(object):
            def __len__(self):
                return sys.maxsize
            def __getitem__(self, i):
                return b'x'
        self.assertRaises(MemoryError, _posixsubprocess.fork_exec,
                          1,Z(),3,(1, 2),5,6,7,8,9,10,11,12,13,14,15,16,17)

    @unittest.skipUnless(_posixsubprocess, '_posixsubprocess required for this test.')
    def test_subprocess_fork_exec(self):
        class Z(object):
            def __len__(self):
                return 1

        # Issue #15738: crash in subprocess_fork_exec()
        self.assertRaises(TypeError, _posixsubprocess.fork_exec,
                          Z(),[b'1'],3,(1, 2),5,6,7,8,9,10,11,12,13,14,15,16,17)

    @unittest.skipIf(MISSING_C_DOCSTRINGS,
                     "Signature information for builtins requires docstrings")
    def test_docstring_signature_parsing(self):

        self.assertEqual(_testcapi.no_docstring.__doc__, None)
        self.assertEqual(_testcapi.no_docstring.__text_signature__, None)

        self.assertEqual(_testcapi.docstring_empty.__doc__, None)
        self.assertEqual(_testcapi.docstring_empty.__text_signature__, None)

        self.assertEqual(_testcapi.docstring_no_signature.__doc__,
            "This docstring has no signature.")
        self.assertEqual(_testcapi.docstring_no_signature.__text_signature__, None)

        self.assertEqual(_testcapi.docstring_with_invalid_signature.__doc__,
            "docstring_with_invalid_signature($module, /, boo)\n"
            "\n"
            "This docstring has an invalid signature."
            )
        self.assertEqual(_testcapi.docstring_with_invalid_signature.__text_signature__, None)

        self.assertEqual(_testcapi.docstring_with_invalid_signature2.__doc__,
            "docstring_with_invalid_signature2($module, /, boo)\n"
            "\n"
            "--\n"
            "\n"
            "This docstring also has an invalid signature."
            )
        self.assertEqual(_testcapi.docstring_with_invalid_signature2.__text_signature__, None)

        self.assertEqual(_testcapi.docstring_with_signature.__doc__,
            "This docstring has a valid signature.")
        self.assertEqual(_testcapi.docstring_with_signature.__text_signature__, "($module, /, sig)")

        self.assertEqual(_testcapi.docstring_with_signature_but_no_doc.__doc__, None)
        self.assertEqual(_testcapi.docstring_with_signature_but_no_doc.__text_signature__,
            "($module, /, sig)")

        self.assertEqual(_testcapi.docstring_with_signature_and_extra_newlines.__doc__,
            "\nThis docstring has a valid signature and some extra newlines.")
        self.assertEqual(_testcapi.docstring_with_signature_and_extra_newlines.__text_signature__,
            "($module, /, parameter)")

    def test_c_type_with_matrix_multiplication(self):
        M = _testcapi.matmulType
        m1 = M()
        m2 = M()
        self.assertEqual(m1 @ m2, ("matmul", m1, m2))
        self.assertEqual(m1 @ 42, ("matmul", m1, 42))
        self.assertEqual(42 @ m1, ("matmul", 42, m1))
        o = m1
        o @= m2
        self.assertEqual(o, ("imatmul", m1, m2))
        o = m1
        o @= 42
        self.assertEqual(o, ("imatmul", m1, 42))
        o = 42
        o @= m1
        self.assertEqual(o, ("matmul", 42, m1))

    def test_return_null_without_error(self):
        # Issue #23571: A function must not return NULL without setting an
        # error
        if Py_DEBUG:
            code = textwrap.dedent("""
                import _testcapi
                from test import support

                with support.SuppressCrashReport():
                    _testcapi.return_null_without_error()
            """)
            rc, out, err = assert_python_failure('-c', code)
            self.assertRegex(err.replace(b'\r', b''),
                             br'Fatal Python error: a function returned NULL '
                                br'without setting an error\n'
                             br'SystemError: <built-in function '
                                 br'return_null_without_error> returned NULL '
                                 br'without setting an error\n'
                             br'\n'
                             br'Current thread.*:\n'
                             br'  File .*", line 6 in <module>')
        else:
            with self.assertRaises(SystemError) as cm:
                _testcapi.return_null_without_error()
            self.assertRegex(str(cm.exception),
                             'return_null_without_error.* '
                             'returned NULL without setting an error')

    def test_return_result_with_error(self):
        # Issue #23571: A function must not return a result with an error set
        if Py_DEBUG:
            code = textwrap.dedent("""
                import _testcapi
                from test import support

                with support.SuppressCrashReport():
                    _testcapi.return_result_with_error()
            """)
            rc, out, err = assert_python_failure('-c', code)
            self.assertRegex(err.replace(b'\r', b''),
                             br'Fatal Python error: a function returned a '
                                br'result with an error set\n'
                             br'ValueError\n'
                             br'\n'
                             br'The above exception was the direct cause '
                                br'of the following exception:\n'
                             br'\n'
                             br'SystemError: <built-in '
                                br'function return_result_with_error> '
                                br'returned a result with an error set\n'
                             br'\n'
                             br'Current thread.*:\n'
                             br'  File .*, line 6 in <module>')
        else:
            with self.assertRaises(SystemError) as cm:
                _testcapi.return_result_with_error()
            self.assertRegex(str(cm.exception),
                             'return_result_with_error.* '
                             'returned a result with an error set')

    def test_buildvalue_N(self):
        _testcapi.test_buildvalue_N()

    def test_set_nomemory(self):
        code = """if 1:
            import _testcapi

            class C(): pass

            # The first loop tests both functions and that remove_mem_hooks()
            # can be called twice in a row. The second loop checks a call to
            # set_nomemory() after a call to remove_mem_hooks(). The third
            # loop checks the start and stop arguments of set_nomemory().
            for outer_cnt in range(1, 4):
                start = 10 * outer_cnt
                for j in range(100):
                    if j == 0:
                        if outer_cnt != 3:
                            _testcapi.set_nomemory(start)
                        else:
                            _testcapi.set_nomemory(start, start + 1)
                    try:
                        C()
                    except MemoryError as e:
                        if outer_cnt != 3:
                            _testcapi.remove_mem_hooks()
                        print('MemoryError', outer_cnt, j)
                        _testcapi.remove_mem_hooks()
                        break
        """
        rc, out, err = assert_python_ok('-c', code)
        self.assertIn(b'MemoryError 1 10', out)
        self.assertIn(b'MemoryError 2 20', out)
        self.assertIn(b'MemoryError 3 30', out)

    def test_mapping_keys_values_items(self):
        class Mapping1(dict):
            def keys(self):
                return list(super().keys())
            def values(self):
                return list(super().values())
            def items(self):
                return list(super().items())
        class Mapping2(dict):
            def keys(self):
                return tuple(super().keys())
            def values(self):
                return tuple(super().values())
            def items(self):
                return tuple(super().items())
        dict_obj = {'foo': 1, 'bar': 2, 'spam': 3}

        for mapping in [{}, OrderedDict(), Mapping1(), Mapping2(),
                        dict_obj, OrderedDict(dict_obj),
                        Mapping1(dict_obj), Mapping2(dict_obj)]:
            self.assertListEqual(_testcapi.get_mapping_keys(mapping),
                                 list(mapping.keys()))
            self.assertListEqual(_testcapi.get_mapping_values(mapping),
                                 list(mapping.values()))
            self.assertListEqual(_testcapi.get_mapping_items(mapping),
                                 list(mapping.items()))

    def test_mapping_keys_values_items_bad_arg(self):
        self.assertRaises(AttributeError, _testcapi.get_mapping_keys, None)
        self.assertRaises(AttributeError, _testcapi.get_mapping_values, None)
        self.assertRaises(AttributeError, _testcapi.get_mapping_items, None)

        class BadMapping:
            def keys(self):
                return None
            def values(self):
                return None
            def items(self):
                return None
        bad_mapping = BadMapping()
        self.assertRaises(TypeError, _testcapi.get_mapping_keys, bad_mapping)
        self.assertRaises(TypeError, _testcapi.get_mapping_values, bad_mapping)
        self.assertRaises(TypeError, _testcapi.get_mapping_items, bad_mapping)


class TestPendingCalls(unittest.TestCase):

    def pendingcalls_submit(self, l, n):
        def callback():
            #this function can be interrupted by thread switching so let's
            #use an atomic operation
            l.append(None)

        for i in range(n):
            time.sleep(random.random()*0.02) #0.01 secs on average
            #try submitting callback until successful.
            #rely on regular interrupt to flush queue if we are
            #unsuccessful.
            while True:
                if _testcapi._pending_threadfunc(callback):
                    break;

    def pendingcalls_wait(self, l, n, context = None):
        #now, stick around until l[0] has grown to 10
        count = 0;
        while len(l) != n:
            #this busy loop is where we expect to be interrupted to
            #run our callbacks.  Note that callbacks are only run on the
            #main thread
            if False and support.verbose:
                print("(%i)"%(len(l),),)
            for i in range(1000):
                a = i*i
            if context and not context.event.is_set():
                continue
            count += 1
            self.assertTrue(count < 10000,
                "timeout waiting for %i callbacks, got %i"%(n, len(l)))
        if False and support.verbose:
            print("(%i)"%(len(l),))

    def test_pendingcalls_threaded(self):

        #do every callback on a separate thread
        n = 32 #total callbacks
        threads = []
        class foo(object):pass
        context = foo()
        context.l = []
        context.n = 2 #submits per thread
        context.nThreads = n // context.n
        context.nFinished = 0
        context.lock = threading.Lock()
        context.event = threading.Event()

        threads = [threading.Thread(target=self.pendingcalls_thread,
                                    args=(context,))
                   for i in range(context.nThreads)]
        with support.start_threads(threads):
            self.pendingcalls_wait(context.l, n, context)

    def pendingcalls_thread(self, context):
        try:
            self.pendingcalls_submit(context.l, context.n)
        finally:
            with context.lock:
                context.nFinished += 1
                nFinished = context.nFinished
                if False and support.verbose:
                    print("finished threads: ", nFinished)
            if nFinished == context.nThreads:
                context.event.set()

    def test_pendingcalls_non_threaded(self):
        #again, just using the main thread, likely they will all be dispatched at
        #once.  It is ok to ask for too many, because we loop until we find a slot.
        #the loop can be interrupted to dispatch.
        #there are only 32 dispatch slots, so we go for twice that!
        l = []
        n = 64
        self.pendingcalls_submit(l, n)
        self.pendingcalls_wait(l, n)


class SubinterpreterTest(unittest.TestCase):

    def test_subinterps(self):
        import builtins
        r, w = os.pipe()
        code = """if 1:
            import sys, builtins, pickle
            with open({:d}, "wb") as f:
                pickle.dump(id(sys.modules), f)
                pickle.dump(id(builtins), f)
            """.format(w)
        with open(r, "rb") as f:
            ret = support.run_in_subinterp(code)
            self.assertEqual(ret, 0)
            self.assertNotEqual(pickle.load(f), id(sys.modules))
            self.assertNotEqual(pickle.load(f), id(builtins))


# Bug #6012
class Test6012(unittest.TestCase):
    def test(self):
        self.assertEqual(_testcapi.argparsing("Hello", "World"), 1)


class SkipitemTest(unittest.TestCase):

    def test_skipitem(self):
        """
        If this test failed, you probably added a new "format unit"
        in Python/getargs.c, but neglected to update our poor friend
        skipitem() in the same file.  (If so, shame on you!)

        With a few exceptions**, this function brute-force tests all
        printable ASCII*** characters (32 to 126 inclusive) as format units,
        checking to see that PyArg_ParseTupleAndKeywords() return consistent
        errors both when the unit is attempted to be used and when it is
        skipped.  If the format unit doesn't exist, we'll get one of two
        specific error messages (one for used, one for skipped); if it does
        exist we *won't* get that error--we'll get either no error or some
        other error.  If we get the specific "does not exist" error for one
        test and not for the other, there's a mismatch, and the test fails.

           ** Some format units have special funny semantics and it would
              be difficult to accommodate them here.  Since these are all
              well-established and properly skipped in skipitem() we can
              get away with not testing them--this test is really intended
              to catch *new* format units.

          *** Python C source files must be ASCII.  Therefore it's impossible
              to have non-ASCII format units.

        """
        empty_tuple = ()
        tuple_1 = (0,)
        dict_b = {'b':1}
        keywords = ["a", "b"]

        for i in range(32, 127):
            c = chr(i)

            # skip parentheses, the error reporting is inconsistent about them
            # skip 'e', it's always a two-character code
            # skip '|' and '$', they don't represent arguments anyway
            if c in '()e|$':
                continue

            # test the format unit when not skipped
            format = c + "i"
            try:
                _testcapi.parse_tuple_and_keywords(tuple_1, dict_b,
                    format, keywords)
                when_not_skipped = False
            except SystemError as e:
                s = "argument 1 (impossible<bad format char>)"
                when_not_skipped = (str(e) == s)
            except TypeError:
                when_not_skipped = False

            # test the format unit when skipped
            optional_format = "|" + format
            try:
                _testcapi.parse_tuple_and_keywords(empty_tuple, dict_b,
                    optional_format, keywords)
                when_skipped = False
            except SystemError as e:
                s = "impossible<bad format char>: '{}'".format(format)
                when_skipped = (str(e) == s)

            message = ("test_skipitem_parity: "
                "detected mismatch between convertsimple and skipitem "
                "for format unit '{}' ({}), not skipped {}, skipped {}".format(
                    c, i, when_skipped, when_not_skipped))
            self.assertIs(when_skipped, when_not_skipped, message)

    def test_parse_tuple_and_keywords(self):
        # Test handling errors in the parse_tuple_and_keywords helper itself
        self.assertRaises(TypeError, _testcapi.parse_tuple_and_keywords,
                          (), {}, 42, [])
        self.assertRaises(ValueError, _testcapi.parse_tuple_and_keywords,
                          (), {}, '', 42)
        self.assertRaises(ValueError, _testcapi.parse_tuple_and_keywords,
                          (), {}, '', [''] * 42)
        self.assertRaises(ValueError, _testcapi.parse_tuple_and_keywords,
                          (), {}, '', [42])

    def test_bad_use(self):
        # Test handling invalid format and keywords in
        # PyArg_ParseTupleAndKeywords()
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (1,), {}, '||O', ['a'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (1, 2), {}, '|O|O', ['a', 'b'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {'a': 1}, '$$O', ['a'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {'a': 1, 'b': 2}, '$O$O', ['a', 'b'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {'a': 1}, '$|O', ['a'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {'a': 1, 'b': 2}, '$O|O', ['a', 'b'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (1,), {}, '|O', ['a', 'b'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (1,), {}, '|OO', ['a'])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {}, '|$O', [''])
        self.assertRaises(SystemError, _testcapi.parse_tuple_and_keywords,
                          (), {}, '|OO', ['a', ''])

    def test_positional_only(self):
        parse = _testcapi.parse_tuple_and_keywords

        parse((1, 2, 3), {}, 'OOO', ['', '', 'a'])
        parse((1, 2), {'a': 3}, 'OOO', ['', '', 'a'])
        with self.assertRaisesRegex(TypeError,
               r'function takes at least 2 positional arguments \(1 given\)'):
            parse((1,), {'a': 3}, 'OOO', ['', '', 'a'])
        parse((1,), {}, 'O|OO', ['', '', 'a'])
        with self.assertRaisesRegex(TypeError,
               r'function takes at least 1 positional arguments \(0 given\)'):
            parse((), {}, 'O|OO', ['', '', 'a'])
        parse((1, 2), {'a': 3}, 'OO$O', ['', '', 'a'])
        with self.assertRaisesRegex(TypeError,
               r'function takes exactly 2 positional arguments \(1 given\)'):
            parse((1,), {'a': 3}, 'OO$O', ['', '', 'a'])
        parse((1,), {}, 'O|O$O', ['', '', 'a'])
        with self.assertRaisesRegex(TypeError,
               r'function takes at least 1 positional arguments \(0 given\)'):
            parse((), {}, 'O|O$O', ['', '', 'a'])
        with self.assertRaisesRegex(SystemError, r'Empty parameter name after \$'):
            parse((1,), {}, 'O|$OO', ['', '', 'a'])
        with self.assertRaisesRegex(SystemError, 'Empty keyword'):
            parse((1,), {}, 'O|OO', ['', 'a', ''])


class TestThreadState(unittest.TestCase):

    @support.reap_threads
    def test_thread_state(self):
        # some extra thread-state tests driven via _testcapi
        def target():
            idents = []

            def callback():
                idents.append(threading.get_ident())

            _testcapi._test_thread_state(callback)
            a = b = callback
            time.sleep(1)
            # Check our main thread is in the list exactly 3 times.
            self.assertEqual(idents.count(threading.get_ident()), 3,
                             "Couldn't find main thread correctly in the list")

        target()
        t = threading.Thread(target=target)
        t.start()
        t.join()


class Test_testcapi(unittest.TestCase):
    def test__testcapi(self):
        if support.verbose:
            print()
        for name in dir(_testcapi):
            if not name.startswith('test_'):
                continue
            with self.subTest("internal", name=name):
                if support.verbose:
                    print(f"  {name}", flush=True)
                test = getattr(_testcapi, name)
                test()


class PyMemDebugTests(unittest.TestCase):
    PYTHONMALLOC = 'debug'
    # '0x04c06e0' or '04C06E0'
    PTR_REGEX = r'(?:0x)?[0-9a-fA-F]+'

    def check(self, code):
        with support.SuppressCrashReport():
            out = assert_python_failure('-c', code,
                                        PYTHONMALLOC=self.PYTHONMALLOC)
        stderr = out.err
        return stderr.decode('ascii', 'replace')

    def test_buffer_overflow(self):
        out = self.check('import _testcapi; _testcapi.pymem_buffer_overflow()')
        regex = (r"Debug memory block at address p={ptr}: API 'm'\n"
                 r"    16 bytes originally requested\n"
                 r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
                 r"    The [0-9] pad bytes at tail={ptr} are not all FORBIDDENBYTE \(0x[0-9a-f]{{2}}\):\n"
                 r"        at tail\+0: 0x78 \*\*\* OUCH\n"
                 r"        at tail\+1: 0xfb\n"
                 r"        at tail\+2: 0xfb\n"
                 r"        .*\n"
                 r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
                 r"    Data at p: cb cb cb .*\n"
                 r"\n"
                 r"Fatal Python error: bad trailing pad byte")
        regex = regex.format(ptr=self.PTR_REGEX)
        regex = re.compile(regex, flags=re.DOTALL)
        self.assertRegex(out, regex)

    def test_api_misuse(self):
        out = self.check('import _testcapi; _testcapi.pymem_api_misuse()')
        regex = (r"Debug memory block at address p={ptr}: API 'm'\n"
                 r"    16 bytes originally requested\n"
                 r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
                 r"    The [0-9] pad bytes at tail={ptr} are FORBIDDENBYTE, as expected.\n"
                 r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
                 r"    Data at p: cb cb cb .*\n"
                 r"\n"
                 r"Fatal Python error: bad ID: Allocated using API 'm', verified using API 'r'\n")
        regex = regex.format(ptr=self.PTR_REGEX)
        self.assertRegex(out, regex)

    def check_malloc_without_gil(self, code):
        out = self.check(code)
        expected = ('Fatal Python error: Python memory allocator called '
                    'without holding the GIL')
        self.assertIn(expected, out)

    def test_pymem_malloc_without_gil(self):
        # Debug hooks must raise an error if PyMem_Malloc() is called
        # without holding the GIL
        code = 'import _testcapi; _testcapi.pymem_malloc_without_gil()'
        self.check_malloc_without_gil(code)

    def test_pyobject_malloc_without_gil(self):
        # Debug hooks must raise an error if PyObject_Malloc() is called
        # without holding the GIL
        code = 'import _testcapi; _testcapi.pyobject_malloc_without_gil()'
        self.check_malloc_without_gil(code)


class PyMemMallocDebugTests(PyMemDebugTests):
    PYTHONMALLOC = 'malloc_debug'


@unittest.skipUnless(support.with_pymalloc(), 'need pymalloc')
class PyMemPymallocDebugTests(PyMemDebugTests):
    PYTHONMALLOC = 'pymalloc_debug'


@unittest.skipUnless(Py_DEBUG, 'need Py_DEBUG')
class PyMemDefaultTests(PyMemDebugTests):
    # test default allocator of Python compiled in debug mode
    PYTHONMALLOC = ''


if __name__ == "__main__":
    unittest.main()