chore: addressed review feedback

packages/leaderboard_repository/lib/src/leaderboard_repository.dart

@@ -72,6 +72,20 @@ class FetchPlayerRankingException extends LeaderboardException {
         );
 }
 
+/// {@template fetch_prohibited_initials_exception}
+/// Exception thrown when failure occurs while fetching prohibited initials.
+/// {@endtemplate}
+class FetchProhibitedInitialsException extends LeaderboardException {
+  /// {@macro fetch_prohibited_initials_exception}
+  const FetchProhibitedInitialsException(
+    Object error,
+    StackTrace stackTrace,
+  ) : super(
+          error,
+          stackTrace,
+        );
+}
+
 /// {@template leaderboard_repository}
 /// Repository to access leaderboard data in Firebase Cloud Firestore.
 /// {@endtemplate}
@@ -153,14 +167,28 @@ class LeaderboardRepository {
     }
   }
 
-  /// Checks if the given [username] is allowed. The [username] is not allowed
-  /// if it is a bad word.
-  Future<bool> isUsernameAllowed({required String username}) async {
-    // TODO(jonathandaniels-vgv): load this list of bad words from an endpoint
-    final badWords = <String>['badword'];
-    final filteredUsername = username.trim().toLowerCase();
-    final isUsernameABadWord = badWords.contains(filteredUsername);
-    final isUsernameAllowed = !isUsernameABadWord;
-    return isUsernameAllowed;
+  /// Determines if the given [initials] are allowed.
+  Future<bool> areInitialsAllowed({required String initials}) async {
+    // Initials can only be three uppercase A-Z letters
+    final initialsRegex = RegExp(r'^[A-Z]{3}$');
+    if (!initialsRegex.hasMatch(initials)) {
+      return false;
+    }
+
+    try {
+      final document = await _firebaseFirestore
+          .collection('prohibitedInitials')
+          .doc('list')
+          .get();
+      final prohibitedInitials = List<String>.from(
+        document.get('prohibitedInitials') as List,
+      );
+      final isProhibited = prohibitedInitials.contains(
+        initials.trim().toLowerCase(),
+      );
+      return !isProhibited;
+    } on Exception catch (error, stackTrace) {
+      throw FetchProhibitedInitialsException(error, stackTrace);
+    }
   }
 }

packages/leaderboard_repository/test/src/leaderboard_repository_test.dart

@@ -21,6 +21,9 @@ class MockQueryDocumentSnapshot extends Mock
 class MockDocumentReference extends Mock
     implements DocumentReference<Map<String, dynamic>> {}
 
+class MockDocumentSnapshot extends Mock
+    implements DocumentSnapshot<Map<String, dynamic>> {}
+
 void main() {
   group('LeaderboardRepository', () {
     late FirebaseFirestore firestore;
@@ -224,17 +227,32 @@ void main() {
       });
     });
 
-    group('isUsernameAllowed', () {
+    group('areInitialsAllowed', () {
       late LeaderboardRepository leaderboardRepository;
+      late CollectionReference<Map<String, dynamic>> collectionReference;
+      late DocumentReference<Map<String, dynamic>> documentReference;
+      late DocumentSnapshot<Map<String, dynamic>> documentSnapshot;
 
       setUp(() async {
+        collectionReference = MockCollectionReference();
+        documentReference = MockDocumentReference();
+        documentSnapshot = MockDocumentSnapshot();
         leaderboardRepository = LeaderboardRepository(firestore);
+
+        when(() => firestore.collection('prohibitedInitials'))
+            .thenReturn(collectionReference);
+        when(() => collectionReference.doc('list'))
+            .thenReturn(documentReference);
+        when(() => documentReference.get())
+            .thenAnswer((_) async => documentSnapshot);
+        when<dynamic>(() => documentSnapshot.get('prohibitedInitials'))
+            .thenReturn(['bad']);
       });
 
-      test('returns true if username is not a bad word', () async {
+      test('returns true if initials are three letters and allowed', () async {
         final isUsernameAllowedResponse =
-            await leaderboardRepository.isUsernameAllowed(
-          username: 'goodword',
+            await leaderboardRepository.areInitialsAllowed(
+          initials: 'ABC',
         );
         expect(
           isUsernameAllowedResponse,
@@ -242,27 +260,60 @@ void main() {
         );
       });
 
-      test('returns false if username is a bad word', () async {
-        final isUsernameAllowedResponse =
-            await leaderboardRepository.isUsernameAllowed(
-          username: 'badword',
-        );
-        expect(
-          isUsernameAllowedResponse,
-          isFalse,
-        );
-      });
+      test(
+        'returns false if initials are shorter than 3 characters',
+        () async {
+          final areInitialsAllowedResponse =
+              await leaderboardRepository.areInitialsAllowed(initials: 'AB');
+          expect(areInitialsAllowedResponse, isFalse);
+        },
+      );
 
-      test('bad word detection should be case insensitive', () async {
-        final isUsernameAllowedResponse =
-            await leaderboardRepository.isUsernameAllowed(
-          username: '  bAdWoRd  ',
-        );
-        expect(
-          isUsernameAllowedResponse,
-          isFalse,
-        );
+      test(
+        'returns false if initials are longer than 3 characters',
+        () async {
+          final areInitialsAllowedResponse =
+              await leaderboardRepository.areInitialsAllowed(initials: 'ABCD');
+          expect(areInitialsAllowedResponse, isFalse);
+        },
+      );
+
+      test(
+        'returns false if initials contain a lowercase letter',
+        () async {
+          final areInitialsAllowedResponse =
+              await leaderboardRepository.areInitialsAllowed(initials: 'AbC');
+          expect(areInitialsAllowedResponse, isFalse);
+        },
+      );
+
+      test(
+        'returns false if initials contain a special character',
+        () async {
+          final areInitialsAllowedResponse =
+              await leaderboardRepository.areInitialsAllowed(initials: 'A@C');
+          expect(areInitialsAllowedResponse, isFalse);
+        },
+      );
+
+      test('returns false if initials are forbidden', () async {
+        final areInitialsAllowedResponse =
+            await leaderboardRepository.areInitialsAllowed(initials: 'BAD');
+        expect(areInitialsAllowedResponse, isFalse);
       });
+
+      test(
+        'throws FetchProhibitedInitialsException when Exception occurs '
+        'when trying to retrieve information from firestore',
+        () async {
+          when(() => firestore.collection('prohibitedInitials'))
+              .thenThrow(Exception('oops'));
+          expect(
+            () => leaderboardRepository.areInitialsAllowed(initials: 'ABC'),
+            throwsA(isA<FetchProhibitedInitialsException>()),
+          );
+        },
+      );
     });
   });
 }