respect bundle defined app channels for charmstore

shrinkwrap.py

@@ -173,10 +173,10 @@ def _charmhub_downloader(self, name, target, channel=None):
             return zipfile.ZipFile(BytesIO(resp.content)).extractall(rsc_target)
 
     def _charmstore_downloader(self, name, target, channel=None):
-        with status(f'Downloading "{name}" from charm store'):
-            _, rsc_target = self.to_args(target, channel=None)
+        with status(f'Downloading "{name} {channel}" from charm store'):
+            _, rsc_target = self.to_args(target, channel=channel)
             url = f"{self.CS_URL}/{name}/archive"
-            resp = requests.get(url)
+            resp = requests.get(url, params={"channel": channel})
             return zipfile.ZipFile(BytesIO(resp.content)).extractall(rsc_target)
 
 
@@ -458,12 +458,11 @@ def download(args, root):
                     check_call(shlx(f"ln -r -s {snaps.empty_snap} {snap_resource}"))
             else:
                 # This isn't a snap, pull the resource from the appropriate store
-                bundle_resource_revision = app["resources"].get(resources)
-                if bundle_resource_revision and bundle_resource_revision != resource.revision:
-                    # if the bundle's revision doesn't match the charm's default revision, update from bundle
-                    resource = Resource(
-                        resource.name, resource.type, resource.path, bundle_resource_revision, resource.url_format
-                    )
+                # use the bundle provided resource revision if available
+                resource_rev = app["resources"].get(resources) or resource.revision
+                resource = Resource(
+                    resource.name, resource.type, resource.path, resource_rev, resource.url_format
+                )
                 resources.mark_download(app_name, charm, resource)
 
     base_snaps = ["core18", "core20", "lxd", "snapd"]

tests/unit/test_bundle_downloader.py

@@ -74,7 +74,9 @@ def test_charmstore_downloader(mock_zipfile, mock_get, tmpdir):
     downloader = BundleDownloader(tmpdir, args)
     result = downloader.bundle_download()
     assert result is mock_downloaded
-    mock_get.assert_called_once_with("https://api.jujucharms.com/charmstore/v5/kubernetes-unit-test/archive")
+    mock_get.assert_called_once_with(
+        "https://api.jujucharms.com/charmstore/v5/kubernetes-unit-test/archive", params={"channel": args.channel}
+    )
     mock_zipfile.assert_called_once()
     assert isinstance(mock_zipfile.call_args.args[0], BytesIO)