fix: make namespace for local keys NOT mandatory

packages/at_client/CHANGELOG.md

@@ -1,4 +1,5 @@
 ## 3.0.66
+- feat: make namespace NOT mandatory for local keys
 - feat: deprecate useAtChops experimental flag and remove fallback code using private key from preferences/EncryptionUtil methods
 - updated at_commons to `'3.0.57'`, at_chops to `'1.0.5`, at_persistence_secondary_server to `'3.0.59'` 
 ## 3.0.65

packages/at_client/lib/src/util/at_client_validation.dart

@@ -103,6 +103,7 @@ class AtClientValidation {
     }
     // If namespace is not set on key and in preferences, throw exception
     if ((atKey.namespace == null || atKey.namespace!.isEmpty) &&
+        !atKey.isLocal &&
         (atClientPreference.namespace == null ||
             atClientPreference.namespace!.isEmpty)) {
       throw AtKeyException('namespace is mandatory');

packages/at_client/test/at_key_validation_test.dart

@@ -37,4 +37,49 @@ void main() {
             .setCurrentAtSign(atSign, namespace, preference),
         throwsA(predicate((dynamic e) => e is InvalidAtSignException)));
   });
+
+  test('Verify namespace is mandatory for public key', () {
+    AtKey atKey = AtKey.public('key_no_namespace', sharedBy: '@noname').build();
+    AtClientPreference preference = AtClientPreference()..namespace = null;
+
+    expect(
+        () => AtClientValidation.validatePutRequest(
+            atKey, 'dummyvalue', preference),
+        throwsA(predicate((dynamic e) =>
+            e is AtKeyException && e.message == 'namespace is mandatory')));
+  });
+
+  test('Verify namespace is mandatory for private key', () {
+    AtKey atKey = AtKey.private('key_no_namespace1').build()
+      ..sharedBy = '@noname1';
+    AtClientPreference preference = AtClientPreference()..namespace = null;
+
+    expect(
+        () => AtClientValidation.validatePutRequest(
+            atKey, 'dummyvalue', preference),
+        throwsA(predicate((dynamic e) =>
+            e is AtKeyException && e.message == 'namespace is mandatory')));
+  });
+
+  test('Verify namespace is mandatory for shared key', () {
+    AtKey atKey =
+        (AtKey.shared('key_no_namespace2', namespace: null, sharedBy: '@sharer')
+              ..sharedWith('@sharee'))
+            .build();
+    AtClientPreference preference = AtClientPreference()..namespace = null;
+
+    expect(
+        () => AtClientValidation.validatePutRequest(
+            atKey, 'dummyvalue', preference),
+        throwsA(predicate((dynamic e) =>
+            e is AtKeyException && e.message == 'namespace is mandatory')));
+  });
+
+  test('Verify namespace is NOT mandatory for local key', () {
+    AtKey atKey = AtKey.local('key_no_namespace3', '@sharer').build();
+    AtClientPreference preference = AtClientPreference()..namespace = null;
+    // validatePutRequest() has a return type of void
+    // error-less execution of this method should be considered as test passing
+    AtClientValidation.validatePutRequest(atKey, 'dummyvalue', preference);
+  });
 }