Fix _verify_nova_compute (#397)

- logic was getting the app as a string instead of the object
- fix unit tests

Closes: #393

cou/apps/auxiliary.py

@@ -351,7 +351,7 @@ async def _verify_nova_compute(self, target: OpenStackRelease) -> None:
         units_not_upgraded = []
         apps = await self.model.get_applications()
 
-        for app in apps:
+        for app in apps.values():
             if app.charm != "nova-compute":
                 logger.debug("skipping application %s", app.name)
                 continue

tests/unit/apps/test_auxiliary.py

@@ -1202,7 +1202,7 @@ async def test_ceph_osd_verify_nova_compute_no_app(model):
         },
         workload_version="15.2.0",
     )
-    model.get_applications.return_value = [app]
+    model.get_applications.return_value = {"ceph-osd": app}
 
     await app._verify_nova_compute(target)
 
@@ -1288,7 +1288,7 @@ async def test_ceph_osd_verify_nova_compute_pass(mock_lookup, model):
         },
         workload_version="17.0.1",
     )
-    model.get_applications.return_value = [app, nova_compute]
+    model.get_applications.return_value = {"ceph-osd": app, "nova-compute": nova_compute}
 
     await app._verify_nova_compute(target)
 
@@ -1327,7 +1327,7 @@ async def test_ceph_osd_verify_nova_compute_fail(mock_lookup, model):
         },
         workload_version="17.0.1",
     )
-    model.get_applications.return_value = [app, nova_compute]
+    model.get_applications.return_value = {"ceph-osd": app, "nova-compute": nova_compute}
 
     with pytest.raises(ApplicationError, match=f"Units 'nova-compute/0' did not reach {target}."):
         await app._verify_nova_compute(target)