test_fileinput.py 文件源码

def test_readline(self):
        with open(TESTFN, 'wb') as f:
            f.write('A\nB\r\nC\r')
            # Fill TextIOWrapper buffer.
            f.write('123456789\n' * 1000)
            # Issue #20501: readline() shouldn't read whole file.
            f.write('\x80')
        self.addCleanup(safe_unlink, TESTFN)

        fi = FileInput(files=TESTFN, openhook=hook_encoded('ascii'))
        # The most likely failure is a UnicodeDecodeError due to the entire
        # file being read when it shouldn't have been.
        self.assertEqual(fi.readline(), u'A\n')
        self.assertEqual(fi.readline(), u'B\r\n')
        self.assertEqual(fi.readline(), u'C\r')
        with self.assertRaises(UnicodeDecodeError):
            # Read to the end of file.
            list(fi)
        fi.close()