Ensure valid charm origin for local charm switches

Ensure that we provide the server with a valid charm origin when
switching to local charms. Previosuly, we simply sent back the same
charm origin when switching to a local charm.

However, this is not valid, since we don't know where we switched from.
If it's a charmhub charm, it's origin will not be valid.

Also, parse the revision from the new charm url the server sends us

This is equivalent to: juju/juju#16434

Author: jack-w-shaw

examples/local_refresh.py

@@ -20,7 +20,7 @@ async def main():
 
     try:
         print('Get deployed application')
-        app = model.appplications["ubuntu"]
+        app = model.applications["ubuntu"]
 
         print('Refresh/Upgrade Ubuntu charm with local charm')
         await app.refresh(path="path/to/local/ubuntu.charm")

juju/application.py

@@ -848,6 +848,17 @@ async def local_refresh(
                                                              metadata,
                                                              resources=resources)
 
+        # We know this charm is a local charm, but this charm origin could be
+        # the charm origin of a charmhub charm. Ensure that we update/remove
+        # the appropriate fields.
+        charm_origin.source = "local"
+        charm_origin.track = None
+        charm_origin.risk = None
+        charm_origin.branch = None
+        charm_origin.hash_ = None
+        charm_origin.id_ = None
+        charm_origin.revision = URL.parse(charm_url).revision
+
         set_charm_args = {
             'application': self.entity_id,
             'charm_origin': charm_origin,

tests/integration/test_application.py

@@ -9,6 +9,7 @@
 from .. import base
 from juju import jasyncio, errors
 from juju.url import URL, Schema
+from juju.client import client
 
 MB = 1
 
@@ -232,6 +233,22 @@ async def test_refresh_charmhub_to_local(event_loop):
         assert app.data['charm-url'].startswith('local:')
 
 
+@base.bootstrapped
+@pytest.mark.asyncio
+async def test_local_refresh(event_loop):
+    charm_path = INTEGRATION_TEST_DIR / 'charm'
+    async with base.CleanModel() as model:
+        app = await model.deploy('ubuntu')
+        origin = client.CharmOrigin(source="charm-hub", track="20.04", risk="stable",
+                                    branch="deadbeef", hash_="hash", id_="id", revision=12,
+                                    base=client.Base("20.04", "ubuntu"))
+
+        await app.local_refresh(charm_origin=origin, path=charm_path)
+
+        assert origin == client.CharmOrigin(source="local", revision=0,
+                                            base=client.Base("20.04", "ubuntu"))
+
+
 @base.bootstrapped
 @pytest.mark.asyncio
 async def test_trusted(event_loop):