Fix issues found by CodeQL

library/network_connections.py
- 'except' clause does nothing but pass and there is no
  explanatory comment.
- Local variable 'dev_state' may be used before it is initialized.
- Local variable 'dev_id' may be used before it is initialized.

module_utils/network_lsr/argument_validator.py
- 'except' clause does nothing but pass and there is no
  explanatory comment.

module_utils/network_lsr/utils.py
- Mixing implicit and explicit returns may indicate an error
  as implicit returns always return None.

tests/unit/test_network_connections.py
- Module 'network_lsr.argument_validator' is imported with both
  'import' and 'import from'.
- assertTrue(a == b) cannot provide an informative message.
  Using assertEqual(a, b) instead will give more informative
  messages.

Signed-off-by: Noriko Hosoi <nhosoi@redhat.com>

library/network_connections.py

@@ -818,12 +818,14 @@ def connection_compare(
             try:
                 con_a.normalize()
             except Exception:
+                # It's already checked normalize is successful.
                 pass
         if normalize_b:
             con_b = NM.SimpleConnection.new_clone(con_b)
             try:
                 con_b.normalize()
             except Exception:
+                # It's already checked normalize is successful.
                 pass
         if compare_flags is None:
             compare_flags = NM.SettingCompareFlags.IGNORE_TIMESTAMP
@@ -1493,8 +1495,7 @@ def check_activated(ac, dev):
             except AttributeError:
                 ac_reason = None
 
-            if dev:
-                dev_state = dev.get_state()
+            dev_state = dev.get_state() if dev else None
 
             if ac_state == NM.ActiveConnectionState.ACTIVATING:
                 if (
@@ -1528,7 +1529,7 @@ def check_activated(ac, dev):
                     )
                 # the state of the active connection is not very helpful.
                 # see if the device-state is better.
-                if (
+                if dev_state is not None and (
                     dev_state <= NM.DeviceState.DISCONNECTED
                     or dev_state > NM.DeviceState.DEACTIVATING
                 ):
@@ -1567,10 +1568,11 @@ def check_activated_cb():
                 )
             except Exception:
                 ac_id = None
-            if dev:
-                dev_id = dev.connect(
-                    "notify::state", lambda source, pspec: check_activated_cb()
-                )
+            dev_id = (
+                dev.connect("notify::state", lambda source, pspec: check_activated_cb())
+                if dev
+                else None
+            )
 
             try:
                 if not Util.GMainLoop_run(wait_time):
@@ -2550,6 +2552,8 @@ def forget_nm_connection(self, path):
                 ]
             )
         except Exception:
+            # Assume that NetworkManager is not present.
+            # There is no connection to forget.
             pass
 
     def run_action_absent(self, idx):

module_utils/network_lsr/argument_validator.py

@@ -271,6 +271,7 @@ def _validate_impl(self, value, name):
                 except Exception:
                     table = value
         except Exception:
+            # Exception handling is done next.
             pass
         if table is None:
             raise ValidationError(
@@ -336,6 +337,7 @@ def _validate_impl(self, value, name):
                 if isinstance(value, Util.STRING_TYPE) or v2 == value:
                     v = v2
         except Exception:
+            # Exception handling is done next.
             pass
         if v is None:
             raise ValidationError(
@@ -374,11 +376,13 @@ def _validate_impl(self, value, name):
                 try:
                     range = (int(match_group.group(1)), int(match_group.group(2)))
                 except Exception:
+                    # Exception handling is done below.
                     pass
             else:
                 try:
                     range = (int(value), int(value))
                 except Exception:
+                    # Exception handling is done below.
                     pass
         elif isinstance(value, bool):
             # bool can (probably) be converted to integer type,
@@ -425,6 +429,7 @@ def _validate_impl(self, value, name):
             if isinstance(value, Util.STRING_TYPE) or isinstance(value, int):
                 return Util.boolean(value)
         except Exception:
+            # Exception handling is done next.
             pass
         raise ValidationError(name, "must be an boolean but is '%s'" % (value))
 
@@ -2665,6 +2670,7 @@ def _parse_route_tables_mapping(cls, file_content, mapping):
                     try:
                         tableid = int(table[2:], 16)
                     except Exception:
+                        # Exception handling is done next.
                         pass
             if tableid is None or tableid < 0 or tableid > 0xFFFFFFFF:
                 continue

module_utils/network_lsr/utils.py

@@ -339,6 +339,7 @@ def addr_family_norm(addr_family):
         if addr_family in ["6", "inet6", "ip6", "ipv6", "IPv6"]:
             return socket.AF_INET6
         Util.addr_family_check(addr_family)
+        return None
 
     @staticmethod
     def addr_family_prefix_length(family):
@@ -348,6 +349,7 @@ def addr_family_prefix_length(family):
         if addr_family == socket.AF_INET6:
             return 128
         Util.addr_family_check(addr_family)
+        return None
 
     @staticmethod
     def addr_family_valid_prefix(family, prefix):