devices: adjust API for 'devices: add assignment.device property' change

Make it easy to retrieve DeviceInfo object out of DeviceAssignment
object. The only missing piece of information for that is device class,
so add it. Make it optional, as it can be filled on demand when passing
the object through DeviceCollection (either by listing devices, or
attaching/detaching).

This also makes DeviceCollection._device method not needed anymore.

qubesadmin/devices.py

@@ -34,10 +34,11 @@ Devices are identified by pair of (backend domain, `ident`), where `ident` is
 class DeviceAssignment(object):  # pylint: disable=too-few-public-methods
     ''' Maps a device to a frontend_domain. '''
 
-    def __init__(self, backend_domain, ident, options=None, persistent=False,
+    def __init__(self, backend_domain, ident, options=None,
-                 frontend_domain=None):
+            persistent=False, frontend_domain=None, devclass=None):
         self.backend_domain = backend_domain
         self.ident = ident
+        self.devclass = devclass
         self.options = options or {}
         self.persistent = persistent
         self.frontend_domain = frontend_domain
@@ -55,6 +56,22 @@ class DeviceAssignment(object):  # pylint: disable=too-few-public-methods
         return self.backend_domain == other.backend_domain \
             and self.ident == other.ident
 
+    def clone(self):
+        '''Clone object instance'''
+        return self.__class__(
+            self.backend_domain,
+            self.ident,
+            self.options,
+            self.persistent,
+            self.frontend_domain,
+            self.devclass,
+        )
+
+    @property
+    def device(self):
+        '''Get DeviceInfo object corresponding to this DeviceAssignment'''
+        return self.backend_domain.devices[self.devclass][self.ident]
+
 
 class DeviceInfo(object):
     ''' Holds all information about a device '''
@@ -120,6 +137,10 @@ class DeviceCollection(object):
         else:
             assert device_assignment.frontend_domain == self._vm, \
                 "Trying to attach DeviceAssignment belonging to other domain"
+        if device_assignment.devclass is None:
+            device_assignment.devclass = self._class
+        else:
+            assert device_assignment.devclass == self._class
 
         options = device_assignment.options.copy()
         if device_assignment.persistent:
@@ -143,6 +164,10 @@ class DeviceCollection(object):
         else:
             assert device_assignment.frontend_domain == self._vm, \
                 "Trying to detach DeviceAssignment belonging to other domain"
+        if device_assignment.devclass is None:
+            device_assignment.devclass = self._class
+        else:
+            assert device_assignment.devclass == self._class
 
         self._vm.qubesd_call(None,
             'admin.vm.device.{}.Detach'.format(self._class),
@@ -174,13 +199,14 @@ class DeviceCollection(object):
                 continue
             backend_domain = self._vm.app.domains[backend_domain]
             yield DeviceAssignment(backend_domain, ident, options,
-                persistent=dev_persistent, frontend_domain=self._vm)
+                persistent=dev_persistent, frontend_domain=self._vm,
+                devclass=self._class)
 
     def attached(self):
         '''List devices which are (or may be) attached to this vm '''
 
         for assignment in self.assignments():
-            yield self._device(assignment)
+            yield assignment.device
 
     def persistent(self):
         ''' Devices persistently attached and safe to access before libvirt
@@ -188,13 +214,7 @@ class DeviceCollection(object):
         '''
 
         for assignment in self.assignments(True):
-            yield self._device(assignment)
+            yield assignment.device
-
-    def _device(self, assignment):
-        ''' Helper method for geting a `qubes.devices.DeviceInfo` object from
-            `qubes.devices.DeviceAssignment`. '''
-
-        return assignment.backend_domain.devices[self._class][assignment.ident]
 
     def available(self):
         '''List devices exposed by this vm'''

qubesadmin/tests/devices.py

@@ -161,6 +161,12 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
             ('test-vm', 'admin.vm.device.test.List', None, None)] = \
             b'0\0test-vm2+dev1\n' \
             b'test-vm3+dev2\n'
+        self.app.expected_calls[
+            ('test-vm2', 'admin.vm.device.test.Available', None, None)] = \
+            b'0\0dev1 description=desc\n'
+        self.app.expected_calls[
+            ('test-vm3', 'admin.vm.device.test.Available', None, None)] = \
+            b'0\0dev2 description=desc\n'
         assigns = list(self.vm.devices['test'].assignments())
         self.assertEqual(len(assigns), 2)
         self.assertIsInstance(assigns[0], qubesadmin.devices.DeviceAssignment)
@@ -170,6 +176,9 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
         self.assertEqual(assigns[0].frontend_domain,
             self.app.domains['test-vm'])
         self.assertEqual(assigns[0].options, {})
+        self.assertEqual(assigns[0].devclass, 'test')
+        self.assertEqual(assigns[0].device,
+            self.app.domains['test-vm2'].devices['test']['dev1'])
 
         self.assertIsInstance(assigns[1], qubesadmin.devices.DeviceAssignment)
         self.assertEqual(assigns[1].backend_domain,
@@ -178,6 +187,9 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
         self.assertEqual(assigns[1].frontend_domain,
             self.app.domains['test-vm'])
         self.assertEqual(assigns[1].options, {})
+        self.assertEqual(assigns[1].devclass, 'test')
+        self.assertEqual(assigns[1].device,
+            self.app.domains['test-vm3'].devices['test']['dev2'])
 
         self.assertAllCalled()
 
@@ -196,6 +208,7 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
             self.app.domains['test-vm'])
         self.assertEqual(assigns[0].options, {'ro': 'True'})
         self.assertEqual(assigns[0].persistent, False)
+        self.assertEqual(assigns[0].devclass, 'test')
 
         self.assertIsInstance(assigns[1], qubesadmin.devices.DeviceAssignment)
         self.assertEqual(assigns[1].backend_domain,
@@ -205,6 +218,7 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
             self.app.domains['test-vm'])
         self.assertEqual(assigns[1].options, {'ro': 'False'})
         self.assertEqual(assigns[1].persistent, True)
+        self.assertEqual(assigns[1].devclass, 'test')
 
         self.assertAllCalled()
 
@@ -223,6 +237,7 @@ class TC_00_DeviceCollection(qubesadmin.tests.QubesTestCase):
             self.app.domains['test-vm'])
         self.assertEqual(assigns[0].options, {})
         self.assertEqual(assigns[0].persistent, True)
+        self.assertEqual(assigns[0].devclass, 'test')
         self.assertAllCalled()
 
     def test_042_assignments_non_persistent(self):