Merge pull request #685 from juanmanuel-tirado/JUJU-1353_assumes_directive_breaks

[JUJU-1353] Parse assume directives.

Author: juanmanuel-tirado

examples/charms/onos.charm

@@ -20,4 +20,9 @@ tags:
   # https://jujucharms.com/docs/stable/authors-charm-metadata
   - misc
   - application_development
-subordinate: false
+subordinate: false
+# check: https://juju.is/docs/sdk/assumes for more details 
+assumes:
+  - any_of:
+    - juju >= 2.9
+    - k8s-api

examples/charms/ubuntu/metadata.yaml

@@ -7,12 +7,13 @@
 import re
 import textwrap
 import typing
-import typing_inspect
 from collections import defaultdict
 from glob import glob
 from pathlib import Path
 from typing import Any, Mapping, Sequence, TypeVar
 
+import typing_inspect
+
 from . import codegen
 
 _marker = object()
@@ -664,14 +665,30 @@ def from_json(cls, data):
                 data = json.loads(data)
             except json.JSONDecodeError:
                 raise
-        d = {}
-        for k, v in (data or {}).items():
-            d[cls._toPy.get(k, k)] = v
-
-        try:
+        if isinstance(data, dict):
+            d = {}
+            for k, v in (data or {}).items():
+                d[cls._toPy.get(k, k)] = v
+            try:
+                return cls(**d)
+            except TypeError:
+                raise
+        if isinstance(data, list):
+            # check: https://juju.is/docs/sdk/assumes
+            # assumes are in the form of a list
+            d = {}
+            for entry in data:
+                if '>' or '>=' in entry:
+                    # something like juju >= 2.9.31
+                    i = entry.index('>')
+                    key = entry[:i].strip()
+                    value = entry[i:].strip()
+                    d[key] = value
+                else:
+                    # something like k8s-api
+                    d[entry] = ''
             return cls(**d)
-        except TypeError:
-            raise
+        return None
 
     def serialize(self):
         d = {}