test_fileinput.py 文件源码

def test_fileno_when_ValueError_raised(self):
        class FilenoRaisesValueError(UnconditionallyRaise):
            def __init__(self):
                UnconditionallyRaise.__init__(self, ValueError)
            def fileno(self):
                self.__call__()

        unconditionally_raise_ValueError = FilenoRaisesValueError()
        t = writeTmp(1, ["\n"])
        self.addCleanup(remove_tempfiles, t)
        with FileInput(files=[t]) as fi:
            file_backup = fi._file
            try:
                fi._file = unconditionally_raise_ValueError
                result = fi.fileno()
            finally:
                fi._file = file_backup # make sure the file gets cleaned up

        # sanity check to make sure that our test scenario was actually hit
        self.assertTrue(unconditionally_raise_ValueError.invoked,
                        "_file.fileno() was not invoked")

        self.assertEqual(result, -1, "fileno() should return -1")