Re: [Qemu-devel] [PATCH v5 0/3] Add common QEMU control functionality to qemu-iotests

[Fam Zheng <famz@redhat.com>]

On Mon, 05/05 17:32, Kevin Wolf wrote:
> Am 05.05.2014 um 17:21 hat Stefan Hajnoczi geschrieben:
> > On Wed, Apr 30, 2014 at 10:55:07AM -0400, Jeff Cody wrote:
> > > This adds some common functionality to control QEMU for qemu-iotests.
> > > 
> > > Additionally, test 085 is updated to use this new functionality.
> > > 
> > > Some minor fixups along the way, to clear up spaced pathname issues, 
> > > for common.rc, test 019, and test 086.
> > > 
> > > 
> > > Jeff Cody (3):
> > >   block: qemu-iotests - add common.qemu, for bash-controlled qemu tests
> > 
> > Once a test launches QEMU, it soon needs to parse QMP commands or wait
> > for QMP events.  That doesn't lend itself to the traditional
> > qemu-iotests shell model.  That is why iotests.py exists.
> > 
> > Shell script is a poor language for test cases that go beyond
> > pre-defined commands whose output is saved for diffing.  The string
> > manipulation is clumsy, JSON is not supported, tricks with fifos can
> > easily deadlock or break when a process terminates unexpectedly, etc.
> > 
> > If we go further in the direction of this patch series, we'll duplicate
> > existing iotests.py code and have complex shell tests that are hard to
> > extend.  I think it's time to draw the line and convert any test cases
> > that need to complexity to Python.
> > 
> > Why not use iotests.py?
> 
> Because it's hard to use. The "compare against reference output" thing
> is the first thing that you lose with iotests.py, and it's the most
> useful feature in qemu-iotests.
> 
> When a Python test case fails, you get into real debugging. When a shell
> script test case fails, you usually see immediately from the reference
> output diff what's wrong.
> 

Perhaps we should add more error information into iotests.py, if a test case
fails.

Otherwise I don't think iotests.py hard to use though, out of my subjective
point. I agree that shell is not as goog as python in this kind of test.

Fam