Re: [Qemu-block] [PATCH v3] python: Use io.StringIO

[Paolo Bonzini]

On 11/10/2018 13:33, Kevin Wolf wrote:
> 045 1s ...        [13:31:47] [13:31:47] [failed, exit status 1] - output 
> mismatch (see 045.out.bad)
> --- /home/kwolf/source/qemu/tests/qemu-iotests/045.out  2017-01-24 
> 14:49:48.000000000 +0100
> +++ /home/kwolf/source/qemu/tests/qemu-iotests/045.out.bad      2018-10-11 
> 13:31:47.266876850 +0200
> @@ -1,5 +1,26 @@
> -...........
> -----------------------------------------------------------------------
> -Ran 11 tests
> -
> -OK
> +Traceback (most recent call last):
> +  File "045", line 178, in <module>
> +    iotests.main(supported_fmts=['raw'])
> +  File "/home/kwolf/source/qemu/tests/qemu-iotests/iotests.py", line 698, in 
> main
> +    unittest.main(testRunner=MyTestRunner)
> +  File "/usr/lib64/python2.7/unittest/main.py", line 95, in __init__
> +    self.runTests()
> +  File "/usr/lib64/python2.7/unittest/main.py", line 232, in runTests
> +    self.result = testRunner.run(self.test)
> +  File "/usr/lib64/python2.7/unittest/runner.py", line 151, in run
> +    test(result)
> +  File "/usr/lib64/python2.7/unittest/suite.py", line 70, in __call__
> +    return self.run(*args, **kwds)
> +  File "/usr/lib64/python2.7/unittest/suite.py", line 108, in run
> +    test(result)
> +  File "/usr/lib64/python2.7/unittest/suite.py", line 70, in __call__
> +    return self.run(*args, **kwds)
> +  File "/usr/lib64/python2.7/unittest/suite.py", line 108, in run
> +    test(result)
> +  File "/usr/lib64/python2.7/unittest/case.py", line 431, in __call__
> +    return self.run(*args, **kwds)
> +  File "/usr/lib64/python2.7/unittest/case.py", line 406, in run
> +    result.addSuccess(self)
> +  File "/usr/lib64/python2.7/unittest/runner.py", line 62, in addSuccess
> +    self.stream.write('.')
> +TypeError: unicode argument expected, got 'str'
> Failures: 045
> Failed 1 of 1 tests
> 
> $ /usr/bin/env python --version
> Python 2.7.15

Indeed, io.StringIO exists in Python 2.7 but it's different!  If Python
2 code is not unicode-friendly (it almost never is) it should use
StringIO.StringIO, for example 'six' defines

  six.StringIO:
    This is an fake file object for textual data. It’s an alias for
    StringIO.StringIO in Python 2 and io.StringIO in Python 3.

  six.BytesIO:
    This is a fake file object for binary data. In Python 2, it’s an
    alias for StringIO.StringIO, but in Python 3, it’s an alias for
    io.BytesIO.

So the solution seems to be a try/except (and then, better move the
"from X import StringIO" to the top of the file then, rather than
keeping it in def main).

Paolo