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

[Max Reitz <mreitz@redhat.com>]

On 24.04.2015 15:55, Alberto Garcia wrote:
> 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?

That would be a bug. Which is what the tests are for. :-)

Max

> 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