Lib/test/test_capi.py

# 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 namedtuple
import os
import pickle
import platform
import random
import re
import subprocess
import sys
import sysconfig
import textwrap
import time
import unittest
from test import support
from test.support import MISSING_C_DOCSTRINGS
from test.support.script_helper import assert_python_failure
try:
    import _posixsubprocess
except ImportError:
    _posixsubprocess = None
try:
    import threading
except ImportError:
    threading = 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")

    @unittest.skipUnless(threading, 'Threading required for this 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()


@unittest.skipUnless(threading, 'Threading required for this test.')
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 EmbeddingTests(unittest.TestCase):
    def setUp(self):
        here = os.path.abspath(__file__)
        basepath = os.path.dirname(os.path.dirname(os.path.dirname(here)))
        exename = "_testembed"
        if sys.platform.startswith("win"):
            ext = ("_d" if "_d" in sys.executable else "") + ".exe"
            exename += ext
            exepath = os.path.dirname(sys.executable)
        else:
            exepath = os.path.join(basepath, "Programs")
        self.test_exe = exe = os.path.join(exepath, exename)
        if not os.path.exists(exe):
            self.skipTest("%r doesn't exist" % exe)
        # This is needed otherwise we get a fatal error:
        # "Py_Initialize: Unable to get the locale encoding
        # LookupError: no codec search functions registered: can't find encoding"
        self.oldcwd = os.getcwd()
        os.chdir(basepath)

    def tearDown(self):
        os.chdir(self.oldcwd)

    def run_embedded_interpreter(self, *args):
        """Runs a test in the embedded interpreter"""
        cmd = [self.test_exe]
        cmd.extend(args)
        p = subprocess.Popen(cmd,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE,
                             universal_newlines=True)
        (out, err) = p.communicate()
        self.assertEqual(p.returncode, 0,
                         "bad returncode %d, stderr is %r" %
                         (p.returncode, err))
        return out, err

    def run_repeated_init_and_subinterpreters(self):
        out, err = self.run_embedded_interpreter("repeated_init_and_subinterpreters")
        self.assertEqual(err, "")

        # The output from _testembed looks like this:
        # --- Pass 0 ---
        # interp 0 <0x1cf9330>, thread state <0x1cf9700>: id(modules) = 139650431942728
        # interp 1 <0x1d4f690>, thread state <0x1d35350>: id(modules) = 139650431165784
        # interp 2 <0x1d5a690>, thread state <0x1d99ed0>: id(modules) = 139650413140368
        # interp 3 <0x1d4f690>, thread state <0x1dc3340>: id(modules) = 139650412862200
        # interp 0 <0x1cf9330>, thread state <0x1cf9700>: id(modules) = 139650431942728
        # --- Pass 1 ---
        # ...

        interp_pat = (r"^interp (\d+) <(0x[\dA-F]+)>, "
                      r"thread state <(0x[\dA-F]+)>: "
                      r"id\(modules\) = ([\d]+)$")
        Interp = namedtuple("Interp", "id interp tstate modules")

        numloops = 0
        current_run = []
        for line in out.splitlines():
            if line == "--- Pass {} ---".format(numloops):
                self.assertEqual(len(current_run), 0)
                if support.verbose:
                    print(line)
                numloops += 1
                continue

            self.assertLess(len(current_run), 5)
            match = re.match(interp_pat, line)
            if match is None:
                self.assertRegex(line, interp_pat)

            # Parse the line from the loop.  The first line is the main
            # interpreter and the 3 afterward are subinterpreters.
            interp = Interp(*match.groups())
            if support.verbose:
                print(interp)
            self.assertTrue(interp.interp)
            self.assertTrue(interp.tstate)
            self.assertTrue(interp.modules)
            current_run.append(interp)

            # The last line in the loop should be the same as the first.
            if len(current_run) == 5:
                main = current_run[0]
                self.assertEqual(interp, main)
                yield current_run
                current_run = []

    def test_subinterps_main(self):
        for run in self.run_repeated_init_and_subinterpreters():
            main = run[0]

            self.assertEqual(main.id, '0')

    def test_subinterps_different_ids(self):
        for run in self.run_repeated_init_and_subinterpreters():
            main, *subs, _ = run

            mainid = int(main.id)
            for i, sub in enumerate(subs):
                self.assertEqual(sub.id, str(mainid + i + 1))

    def test_subinterps_distinct_state(self):
        for run in self.run_repeated_init_and_subinterpreters():
            main, *subs, _ = run

            if '0x0' in main:
                # XXX Fix on Windows (and other platforms): something
                # is going on with the pointers in Programs/_testembed.c.
                # interp.interp is 0x0 and interp.modules is the same
                # between interpreters.
                raise unittest.SkipTest('platform prints pointers as 0x0')

            for sub in subs:
                # A new subinterpreter may have the same
                # PyInterpreterState pointer as a previous one if
                # the earlier one has already been destroyed.  So
                # we compare with the main interpreter.  The same
                # applies to tstate.
                self.assertNotEqual(sub.interp, main.interp)
                self.assertNotEqual(sub.tstate, main.tstate)
                self.assertNotEqual(sub.modules, main.modules)

    @staticmethod
    def _get_default_pipe_encoding():
        rp, wp = os.pipe()
        try:
            with os.fdopen(wp, 'w') as w:
                default_pipe_encoding = w.encoding
        finally:
            os.close(rp)
        return default_pipe_encoding

    def test_forced_io_encoding(self):
        # Checks forced configuration of embedded interpreter IO streams
        out, err = self.run_embedded_interpreter("forced_io_encoding")
        if support.verbose:
            print()
            print(out)
            print(err)
        expected_errors = sys.__stdout__.errors
        expected_stdin_encoding = sys.__stdin__.encoding
        expected_pipe_encoding = self._get_default_pipe_encoding()
        expected_output = '\n'.join([
        "--- Use defaults ---",
        "Expected encoding: default",
        "Expected errors: default",
        "stdin: {in_encoding}:{errors}",
        "stdout: {out_encoding}:{errors}",
        "stderr: {out_encoding}:backslashreplace",
        "--- Set errors only ---",
        "Expected encoding: default",
        "Expected errors: ignore",
        "stdin: {in_encoding}:ignore",
        "stdout: {out_encoding}:ignore",
        "stderr: {out_encoding}:backslashreplace",
        "--- Set encoding only ---",
        "Expected encoding: latin-1",
        "Expected errors: default",
        "stdin: latin-1:{errors}",
        "stdout: latin-1:{errors}",
        "stderr: latin-1:backslashreplace",
        "--- Set encoding and errors ---",
        "Expected encoding: latin-1",
        "Expected errors: replace",
        "stdin: latin-1:replace",
        "stdout: latin-1:replace",
        "stderr: latin-1:backslashreplace"])
        expected_output = expected_output.format(
                                in_encoding=expected_stdin_encoding,
                                out_encoding=expected_pipe_encoding,
                                errors=expected_errors)
        # This is useful if we ever trip over odd platform behaviour
        self.maxDiff = None
        self.assertEqual(out.strip(), expected_output)


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', ''])


@unittest.skipUnless(threading, 'Threading required for this test.')
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):
        for name in dir(_testcapi):
            if name.startswith('test_'):
                with self.subTest("internal", name=name):
                    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)

    @unittest.skipUnless(threading, 'Test requires a GIL (multithreading)')
    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(sysconfig.get_config_var('WITH_PYMALLOC') == 1,
                     '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()