Lookup blockdev D-Bus properties without raising not found exception

If the pool object path is not on the D-Bus, stratisd will not even have
a field for that item in the GetManagedObjects result and will raise an
exception. Do not allow the exception to propagate in this case, but
catch it and return the unknown string.

Signed-off-by: mulhern <amulhern@redhat.com>

Author: mulkieran

src/stratis_cli/_actions/_physical.py

@@ -17,10 +17,14 @@
 
 # isort: STDLIB
 from argparse import Namespace
+from typing import Callable
 
 # isort: THIRDPARTY
 from justbytes import Range
 
+# isort: FIRSTPARTY
+from dbus_client_gen import DbusClientMissingPropertyError
+
 from .._stratisd_constants import BlockDevTiers
 from ._connection import get_object
 from ._constants import TOP_OBJECT
@@ -79,7 +83,23 @@ def list_devices(namespace: Namespace):  # pylint: disable=too-many-locals
             ).search(managed_objects)
         )
 
-        def paths(modev):
+        def catch_missing_property(modev, prop_to_name: Callable) -> str:
+            """
+            Get a property from an modev. If the property is missing,
+            return the TABLE_UNKNOWN_STRING value.
+            """
+            try:
+                return prop_to_name(modev)
+            except DbusClientMissingPropertyError:  # pragma: no cover
+                return TABLE_UNKNOWN_STRING
+
+        def pool_name_lookup(modev) -> str:
+            """
+            Look up a name for a pool.
+            """
+            return path_to_name.get(modev.Pool(), TABLE_UNKNOWN_STRING)
+
+        def paths(modev) -> str:
             """
             Return <physical_path> (<metadata_path>) if they are different,
             otherwise, just <metadata_path>.
@@ -100,37 +120,44 @@ def paths(modev):
                 else f"{physical_path} ({metadata_path})"
             )
 
-        def size(modev):
+        def size(modev) -> str:
             """
             Return in-use size (observed size) if they are different, otherwise
             just in-use size.
             """
             in_use_size = Range(modev.TotalPhysicalSize())
             observed_size = get_property(modev.NewPhysicalSize(), Range, in_use_size)
+
             return (
                 f"{in_use_size}"
                 if in_use_size == observed_size
                 else f"{in_use_size} ({observed_size})"
             )
 
-        def tier_str(value):
+        def tier_str(modev) -> str:
             """
             String representation of a tier.
             """
             try:
-                return str(BlockDevTiers(value))
+                return str(BlockDevTiers(modev.Tier()))
             except ValueError:  # pragma: no cover
                 return TABLE_UNKNOWN_STRING
 
         format_uuid = get_uuid_formatter(namespace.unhyphenated_uuids)
 
+        def uuid_str(modev) -> str:
+            """
+            String representation of UUID.
+            """
+            return format_uuid(modev.Uuid())
+
         tables = [
             [
-                path_to_name.get(modev.Pool(), TABLE_UNKNOWN_STRING),
-                paths(modev),
-                size(modev),
-                tier_str(modev.Tier()),
-                format_uuid(modev.Uuid()),
+                catch_missing_property(modev, pool_name_lookup),
+                catch_missing_property(modev, paths),
+                catch_missing_property(modev, size),
+                catch_missing_property(modev, tier_str),
+                catch_missing_property(modev, uuid_str),
             ]
             for modev in modevs
         ]