Test and cleanup add_storage

Author: cderici

juju/unit.py

@@ -132,18 +132,23 @@ async def add_storage(self, storage_name, pool=None, count=1, size=1024):
         by the charm, which can specify a maximum number of storage instances per unit.
         :param: int size: the required size of the storage instance, in MiB.
 
-        :return:
+        :return: []str storage_tags
         """
-        constraints = None
+        constraints = client.StorageConstraints(count=count)
         if pool:
             constraints = client.StorageConstraints(pool=pool, count=count, size=size)
 
         storage_facade = client.StorageFacade.from_connection(self.connection)
-        return await storage_facade.AddToUnit(storages=[client.StorageAddParams(
+        res = await storage_facade.AddToUnit(storages=[client.StorageAddParams(
             name=storage_name,
             unit=tag.unit(self.name),
             storage=constraints,
         )])
+        result = res.results[0]
+        if result.error is not None:
+            raise JujuError("{}".format(result.error))
+        storage_details = result.result
+        return storage_details.storage_tags
 
     async def attach_storage(self, storage_ids=[]):
         """Attaches existing storage to this unit.

tests/integration/test_model.py

@@ -12,7 +12,7 @@
 
 import pylxd
 import pytest
-from juju import jasyncio
+from juju import jasyncio, tag
 from juju.client import client
 from juju.errors import JujuError, JujuUnitError, JujuConnectionError
 from juju.model import Model, ModelObserver
@@ -1051,3 +1051,14 @@ async def test_model_cache_update(event_loop):
         await model.disconnect()
         await m.disconnect()
         await controller.destroy_models(model_name)
+
+
+@base.bootstrapped
+@pytest.mark.asyncio
+async def test_add_storage(event_loop):
+    async with base.CleanModel() as model:
+        app = await model.deploy('postgresql')
+        await model.wait_for_idle(status="active")
+        unit = app.units[0]
+        ret = await unit.add_storage("pgdata")
+        assert any([tag.storage("pgdata") in s for s in ret])