Method test_pyobject_asfiledescriptor

Lib/test/test_capi/test_file.py:131–171

(self)

            writeobject("abc", NULL, 0)

    def test_pyobject_asfiledescriptor(self):
        # Test PyObject_AsFileDescriptor(obj):
        # - Return obj if obj is an integer.
        # - Return obj.fileno() otherwise.
        # File descriptor must be >= 0.
        asfd = _testlimitedcapi.pyobject_asfiledescriptor

        self.assertEqual(asfd(123), 123)
        self.assertEqual(asfd(0), 0)

        with open(__file__, "rb") as fp:
            self.assertEqual(asfd(fp), fp.fileno())

        # bool emits RuntimeWarning
        msg = r"bool is used as a file descriptor"
        with warnings_helper.check_warnings((msg, RuntimeWarning)):
            self.assertEqual(asfd(True), 1)

        class FakeFile:
            def __init__(self, fd):
                self.fd = fd
            def fileno(self):
                return self.fd

        # file descriptor must be positive
        with self.assertRaises(ValueError):
            asfd(-1)
        with self.assertRaises(ValueError):
            asfd(FakeFile(-1))

        # fileno() result must be an integer
        with self.assertRaises(TypeError):
            asfd(FakeFile("text"))

        # unsupported types
        for obj in ("string", ["list"], object()):
            with self.subTest(obj=obj):
                with self.assertRaises(TypeError):
                    asfd(obj)

        # CRASHES asfd(NULL)

    def test_pyfile_newstdprinter(self):
        # Test PyFile_NewStdPrinter()