Method test_large_readinto

Lib/test/test_os/test_os.py:348–362

(self, size)

                         "needs INT_MAX < PY_SSIZE_T_MAX")
    @support.bigmemtest(size=INT_MAX + 10, memuse=1, dry_run=False)
    def test_large_readinto(self, size):
        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
        create_file(os_helper.TESTFN, b'test')

        # Issue #21932: For readinto the buffer contains the length rather than
        # a length being passed explicitly to read, should still get capped to a
        # valid size / not raise an OverflowError for sizes larger than INT_MAX.
        buffer = bytearray(INT_MAX + 10)
        with open(os_helper.TESTFN, "rb") as fp:
            length = os.readinto(fp.fileno(), buffer)

        # The test does not try to read more than 2 GiB at once because the
        # operating system is free to return less bytes than requested.
        self.assertEqual(length, 4)
        self.assertEqual(buffer[:4], b'test')

    def test_write(self):
        # os.write() accepts bytes- and buffer-like objects but not strings