fix(types): keep plain JSON text in RichBlockPreformatted

telebot/types.py

@@ -14688,20 +14688,28 @@ def de_json(cls, json_string):
         if json_string is None: return None
         if isinstance(json_string, str):
             # "...can be either a String for plain text..."
-            # Only a JSON object is a serialized RichText. Plain text can look
-            # like JSON too, e.g. a "[56]" footnote mark, and stays text.
+            # Only a JSON object that resolves to a known RichText is serialized
+            # RichText. Plain text can look like JSON too, e.g. a "[56]" footnote
+            # mark or a {"foo": "bar"} code sample, and has to stay text.
+            original = json_string
             if not (json_string.startswith('{') and json_string.endswith('}')):
-                return json_string
+                return original
             try:
                 parsed = json.loads(json_string)
             except (ValueError, TypeError):
-                return json_string
+                return original
             if not isinstance(parsed, dict):
-                return json_string
-            json_string = parsed
+                return original
+            result = cls._from_dict(parsed)
+            return original if result is None else result
         elif isinstance(json_string, list):
             # "...an Array of :class:`RichText`..."
             return [RichText.de_json(item) for item in json_string]
+        return cls._from_dict(json_string)
+
+    @classmethod
+    def _from_dict(cls, json_string):
+        """Resolve a parsed RichText dict, or None when its type is unknown."""
         # "...or any of the following types..."
         obj = cls.check_json(json_string)
         type = obj.pop('type', None)

tests/test_types.py

@@ -558,6 +558,19 @@ def test_json_richtext_plain_text_that_looks_like_json():
         assert types.RichText.de_json(text) == text
 
 
+def test_json_richtext_plain_json_object_stays_text():
+    # issue #2646: a preformatted block whose text is a JSON object is still text
+    for text in ['{"foo": "bar"}', '{}', '{"a": [1, 2]}', '{"type": "not_a_richtext"}']:
+        block = types.RichBlockPreformatted.de_json({'text': text, 'language': 'json'})
+        assert block.text == text
+        assert types.RichText.de_json(text) == text
+
+    # a serialized RichText still deserializes
+    bold = types.RichText.de_json('{"type": "bold", "text": "hi"}')
+    assert isinstance(bold, types.RichTextBold)
+    assert bold.text == 'hi'
+
+
 def test_json_richtextitalic():
     json_str = r'{"type": "italic", "text": "Test"}'
     result = types.RichText.de_json(json_str)