Add function to upgrade charm

unit_tests/test_zaza_model.py

@@ -1041,6 +1041,32 @@ disk_formats = ami,ari,aki,vhd,vmdk,raw,qcow2,vdi,iso,root-tar
         with self.assertRaises(asyncio.futures.TimeoutError):
             model.wait_for_agent_status(timeout=0.1)
 
+    def test_upgrade_charm(self):
+        async def _upgrade_charm(channel=None, force_series=False,
+                                 force_units=False, path=None,
+                                 resources=None, revision=None,
+                                 switch=None, model_name=None):
+            return
+        self.patch_object(model, 'get_juju_model', return_value='mname')
+        self.patch_object(model, 'Model')
+        self.patch_object(model, 'get_unit_from_name')
+        self.get_unit_from_name.return_value = self.unit1
+        self.Model.return_value = self.Model_mock
+        app_mock = mock.MagicMock()
+        app_mock.upgrade_charm.side_effect = _upgrade_charm
+        self.mymodel.applications['myapp'] = app_mock
+        model.upgrade_charm(
+            'myapp',
+            switch='cs:~me/new-charm-45')
+        app_mock.upgrade_charm.assert_called_once_with(
+            channel=None,
+            force_series=False,
+            force_units=False,
+            path=None,
+            resources=None,
+            revision=None,
+            switch='cs:~me/new-charm-45')
+
     def test_prepare_series_upgrade(self):
         self.patch_object(model, 'subprocess')
         self.patch_object(model, 'get_juju_model',

zaza/model.py

@@ -1228,6 +1228,48 @@ def set_model_constraints(constraints, model_name=None):
     subprocess.check_call(cmd)
 
 
+async def async_upgrade_charm(application_name, channel=None,
+                              force_series=False, force_units=False,
+                              path=None, resources=None, revision=None,
+                              switch=None, model_name=None):
+    """
+    Upgrade the given charm.
+
+    :param application_name: Name of application on this side of relation
+    :type application_name: str
+    :param channel: Channel to use when getting the charm from the charm store,
+                    e.g. 'development'
+    :type channel: str
+    :param force_series: Upgrade even if series of deployed application is not
+                         supported by the new charm
+    :type force_series: bool
+    :param force_units: Upgrade all units immediately, even if in error state
+    :type force_units: bool
+    :param path: Uprade to a charm located at path
+    :type path: str
+    :param resources: Dictionary of resource name/filepath pairs
+    :type resources: dict
+    :param revision: Explicit upgrade revision
+    :type revision: int
+    :param switch: Crossgrade charm url
+    :type switch: str
+    :param model_name: Name of model to operate on
+    :type model_name: str
+    """
+    async with run_in_model(model_name) as model:
+        app = model.applications[application_name]
+        await app.upgrade_charm(
+            channel=channel,
+            force_series=force_series,
+            force_units=force_units,
+            path=path,
+            resources=resources,
+            revision=revision,
+            switch=switch)
+
+upgrade_charm = sync_wrapper(async_upgrade_charm)
+
+
 class UnitNotFound(Exception):
     """Unit was not found in model."""