process pbm response

src/charm.py

@@ -1003,7 +1003,8 @@ def run_pbm_command(self, cmd: List[str]) -> str:
         Raises:
             subprocess.CalledProcessError
         """
-        return subprocess.check_output(f"charmed-mongodb.pbm {' '.join(cmd)}", shell=True)
+        pbm_response = subprocess.check_output(f"charmed-mongodb.pbm {' '.join(cmd)}", shell=True)
+        return pbm_response.decode("utf-8")
 
     def start_backup_service(self) -> None:
         """Starts the pbm agent.

tests/integration/backup_tests/test_backups.py

@@ -135,7 +135,7 @@ async def test_create_and_list_backups(ops_test: OpsTest) -> None:
     # verify backup is started
     action = await db_unit.run_action(action_name="create-backup")
     backup_result = await action.wait()
-    assert backup_result.results["backup-status"] == "backup started", "backup didn't start"
+    assert "backup started" in backup_result.results["backup-status"], "backup didn't start"
 
     # verify backup is present in the list of backups
     # the action `create-backup` only confirms that the command was sent to the `pbm`. Creating a
@@ -401,4 +401,4 @@ async def test_update_backup_password(ops_test: OpsTest) -> None:
     # verify we still have connection to pbm via creating a backup
     action = await db_unit.run_action(action_name="create-backup")
     backup_result = await action.wait()
-    assert backup_result.results["backup-status"] == "backup started", "backup didn't start"
+    assert "backup started" in backup_result.results["backup-status"], "backup didn't start"