fix: use throw handling to test config immutableness

tests/config.spec.ts

@@ -1,4 +1,3 @@
-/// <reference types="jest-extended" />
 import { Interceptable, MockAgent, setGlobalDispatcher } from 'undici';
 import { commonDbPartialV1, commonS3PartialV1 } from '@map-colonies/schemas';
 import { StatusCodes } from 'http-status-codes';
@@ -304,7 +303,7 @@ describe('config', () => {
       await expect(promise).rejects.toThrow();
     });
 
-    it('should returned on getAll() a full frozen configuration object ', async () => {
+    it('should not allow to modify the root object', async () => {
       const configInstance = await config({
         configName: 'name',
         version: 1,
@@ -315,10 +314,13 @@ describe('config', () => {
       });
 
       const conf = configInstance.getAll();
-      expect(conf).toBeFrozen();
+      const action = () => {
+        conf.host = 'dummmy.host.check';
+      };
+      expect(action).toThrow(/Cannot assign to read only property/);
     });
 
-    it('should returned on get(`ssl`) a frozen sub configuration object ', async () => {
+    it('should not allow to modify the child object', async () => {
       const configInstance = await config({
         configName: 'name',
         version: 1,
@@ -329,7 +331,28 @@ describe('config', () => {
       });
 
       const conf = configInstance.get('ssl');
-      expect(conf).toBeFrozen();
+      const action = () => {
+        conf.enabled = true; // try to change ssl configuration
+      };
+      expect(action).toThrow(/Cannot assign to read only property/);
+    });
+
+    it('should not allow to modify the extracted child object from root', async () => {
+      const configInstance = await config({
+        configName: 'name',
+        version: 1,
+        schema: commonDbPartialV1,
+        configServerUrl: URL,
+        localConfigPath: './tests/config',
+        offlineMode: true,
+      });
+
+      const conf = configInstance.getAll();
+      const sslConf = conf.ssl;
+      const action = () => {
+        sslConf.enabled = true;
+      };
+      expect(action).toThrow(/Cannot assign to read only property/);
     });
   });
 });