emoji: Add EmojiStore.getUnicodeEmojiNameByCode method

Author: sm-sayedi

lib/model/emoji.dart

@@ -119,6 +119,8 @@ mixin EmojiStore {
 
   Iterable<EmojiCandidate> allEmojiCandidates();
 
+  String? getUnicodeEmojiNameByCode(String emojiCode);
+
   // TODO cut debugServerEmojiData once we can query for lists of emoji;
   //   have tests make those queries end-to-end
   Map<String, List<String>>? get debugServerEmojiData;
@@ -144,6 +146,10 @@ mixin ProxyEmojiStore on EmojiStore {
   @override
   Iterable<EmojiCandidate> allEmojiCandidates() => emojiStore.allEmojiCandidates();
 
+  @override
+  String? getUnicodeEmojiNameByCode(String emojiCode) =>
+    emojiStore.getUnicodeEmojiNameByCode(emojiCode);
+
   @override
   Map<String, List<String>>? get debugServerEmojiData => emojiStore.debugServerEmojiData;
 }
@@ -396,6 +402,11 @@ class EmojiStoreImpl extends PerAccountStoreBase with EmojiStore {
     return _allEmojiCandidates ??= _generateAllCandidates();
   }
 
+  @override
+  String? getUnicodeEmojiNameByCode(String emojiCode) =>
+    // TODO(log) if null; not supposed to happen
+    _serverEmojiData?[emojiCode]?.firstOrNull;
+
   void setServerEmojiData(ServerEmojiData data) {
     _serverEmojiData = data.codeToNames;
     _popularCandidates = null;

test/model/emoji_test.dart

@@ -331,6 +331,37 @@ void main() {
     });
   });
 
+  group('getUnicodeEmojiNameByCode', () {
+    test('happy path', () {
+      final store = prepare(unicodeEmoji: {
+        '1f4c5': ['calendar'],
+        '1f34a': ['orange', 'tangerine', 'mandarin'],
+      });
+      check(store.getUnicodeEmojiNameByCode('1f4c5')).equals('calendar');
+      check(store.getUnicodeEmojiNameByCode('1f34a')).equals('orange');
+    });
+
+    test('server emoji data present, emoji code not present', () {
+      final store = prepare(unicodeEmoji: {
+        '1f4c5': ['calendar'],
+      });
+      check(store.getUnicodeEmojiNameByCode('1f34a')).isNull();
+    });
+
+    test('server emoji data present, emoji code corresponds to empty emoji name list', () {
+      final store = prepare(unicodeEmoji: {
+        '1f4c5': [],
+      });
+      check(store.getUnicodeEmojiNameByCode('1f516')).isNull();
+    });
+
+    test('server emoji data is not present', () {
+      final store = prepare(addServerDataForPopular: false);
+      check(store.debugServerEmojiData).isNull();
+      check(store.getUnicodeEmojiNameByCode('1f516')).isNull();
+    });
+  });
+
   group('EmojiAutocompleteView', () {
     Condition<Object?> isUnicodeResult({String? emojiCode, List<String>? names}) {
       return (it) => it.isA<EmojiAutocompleteResult>().candidate.which(