Re: [Qemu-block] [PATCH 08/11] qemu-iotests: add no-op streaming test

[Alberto Garcia]

On Fri 24 Apr 2015 03:19:54 PM CEST, Max Reitz wrote:

>> This patch updates test_stream_partial() to test that the
>> block-stream operation never copies data from the image specified as
>> base.
>
> I think it would be better to add this as an own test case. But I
> won't oppose adding it as a special case of test_stream_partial
> either, because strictly speaking, streaming nothing is a special case
> of streaming partially.

That was the idea, but of course it can be moved to a new test, it's
also fine with me.

>> +        self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-c', 'map', 
>> mid_img),
>> +                            qemu_io('-f', iotests.imgfmt, '-c', 'map', 
>> test_img),
>> +                            'image file map matches backing file after a 
>> no-op')
>
> Well, you haven't really proven anything by doing this, except that
> the mid_img hasn't been streamed completely into test_img... What you
> want to prove is that test_img is empty after streaming, right?

That's right, but what scenario would that be? A streaming operation
that is completed without errors and leaves partial data on the
destination image?

There's only 512 bytes written in mid_img for this test case. If we
suspect that it can go wrong maybe we should start comparing more things
than just the qemu_io map output...

Berto