Re: [Qemu-devel] [PATCH v2 1/2] tests.acceptance: adds multi vm capability for acceptance tests

[Caio Carrara <ccarrara@redhat.com>]

Hi, Wainer.

On Mon, Jan 28, 2019 at 05:42:24PM -0200, Wainer dos Santos Moschetta wrote:
> 
> On 01/28/2019 03:47 PM, Caio Carrara wrote:
> > This change adds the possibility to write acceptance tests with multi
> > virtual machine support. It's done keeping the virtual machines objects
> > stored in a test attribute (dictionary). This dictionary shouldn't be
> > accessed directly but through the new method added `get_vm`. This new
> > method accept a list of args (that will be added as virtual machine
> > arguments) and an optional name argument. The name is the key that
> > identify a single virtual machine along the test machines available. If
> > a name without a machine is informed a new machine will be instantiated.
> > 
> > The current usage of vm in tests will not be broken by this change since
> > it keeps a property called vm in the base test class. This property only
> > calls the new method `get_vm` with default parameters (no args and
> > 'default' as machine name).
> 
> I've checked that current tests does not break by this change. I also
> checked the example you provided on docs/devel/testing.rst works too.
> 
> So Tested-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> 
> > 
> > Signed-off-by: Caio Carrara <ccarrara@redhat.com>
> > ---
> >   docs/devel/testing.rst                    | 40 ++++++++++++++++++++++-
> >   tests/acceptance/avocado_qemu/__init__.py | 25 +++++++++++---
> >   2 files changed, 60 insertions(+), 5 deletions(-)
> > 
> > diff --git a/docs/devel/testing.rst b/docs/devel/testing.rst
> > index 18e2c0868a..b97c0368bc 100644
> > --- a/docs/devel/testing.rst
> > +++ b/docs/devel/testing.rst
> > @@ -634,7 +634,45 @@ instance, available at ``self.vm``.  Because many tests will tweak the
> >   QEMU command line, launching the QEMUMachine (by using ``self.vm.launch()``)
> >   is left to the test writer.
> > -At test "tear down", ``avocado_qemu.Test`` handles the QEMUMachine
> > +The base test class has also support for tests with more than one
> > +QEMUMachine. The way to get machines is through the ``self.get_vm()``
> > +method which will return a QEMUMachine instance. The ``self.get_vm()``
> > +method also accepts an optional `name` attribute so you can identify a
> > +specific machine and get it more than once through the tests methods. A
> > +simple and hypothetical example follows:
> 
> Since you explain the self.get_vm() optional name attribute, you also could
> mention it accepts arguments to be passed to the newly created VM.
> 
> > +
> > +.. code::
> > +
> > +  from avocado_qemu import Test
> > +
> > +
> > +  class MultipleMachines(Test):
> > +      """
> > +      :avocado: enable
> > +      """
> > +      def test_multiple_machines(self):
> > +          first_machine = self.get_vm()
> > +          second_machine = self.get_vm()
> > +          self.get_vm(name='third_machine').launch()
> > +
> > +          first_machine.launch()
> > +          second_machine.launch()
> > +
> > +          first_res = first_machine.command(
> > +              'human-monitor-command',
> > +              command_line='info version')
> > +
> > +          second_res = second_machine.command(
> > +              'human-monitor-command',
> > +              command_line='info version')
> > +
> > +          third_res = self.get_vm(name='third_machine').command(
> > +              'human-monitor-command',
> > +              command_line='info version')
> > +
> > +          self.assertEquals(first_res, second_res, third_res)
> > +
> > +At test "tear down", ``avocado_qemu.Test`` handles all the QEMUMachines
> >   shutdown.
> >   QEMUMachine
> > diff --git a/tests/acceptance/avocado_qemu/__init__.py b/tests/acceptance/avocado_qemu/__init__.py
> > index 1e54fd5932..4c9e27feda 100644
> > --- a/tests/acceptance/avocado_qemu/__init__.py
> > +++ b/tests/acceptance/avocado_qemu/__init__.py
> > @@ -10,6 +10,7 @@
> >   import os
> >   import sys
> > +import uuid
> >   import avocado
> > @@ -42,13 +43,29 @@ def pick_default_qemu_bin():
> >   class Test(avocado.Test):
> >       def setUp(self):
> > -        self.vm = None
> > +        self._vms = {}
> >           self.qemu_bin = self.params.get('qemu_bin',
> >                                           default=pick_default_qemu_bin())
> >           if self.qemu_bin is None:
> >               self.cancel("No QEMU binary defined or found in the source tree")
> > -        self.vm = QEMUMachine(self.qemu_bin)
> > +
> > +    def _new_vm(self, *args):
> > +        vm = QEMUMachine(self.qemu_bin)
> > +        if args:
> > +            vm.add_args(*args)
> > +        return vm
> > +
> > +    @property
> > +    def vm(self):
> > +        return self.get_vm(name='default')
> > +
> > +    def get_vm(self, *args, name=None):
> > +        if not name:
> > +            name = str(uuid.uuid4())
> 
> Beware that if you don't give a name to the VM, the only way to access it
> later is to keep the reference returned by get_vm(). Do you think it is
> something we should care about? or assume the test writer handle this
> (unlikely?) case somehow?

I think it's something e should assume the test writer is going to
handle.
> 
> - Wainer
> 
> > +        if self._vms.get(name) is None:
> > +            self._vms[name] = self._new_vm(*args)
> > +        return self._vms[name]
> >       def tearDown(self):
> > -        if self.vm is not None:
> > -            self.vm.shutdown()
> > +        for vm in self._vms.values():
> > +            vm.shutdown()
> 

Thanks,

-- 
Caio Carrara
Software Engineer, Virt Team - Red Hat
ccarrara@redhat.com