refactor: buttons: Validate PM data prior to narrowing.

This commit adds validation helper for PM data, in an attempt to
avoid and handle any potential exceptions before starting to switch
to the PM narrow. The validation checks if all the recipients IDs
are valid or not.

Tests added and amended.

Author: Ezio-Sarthak

tests/ui_tools/test_buttons.py

@@ -612,6 +612,7 @@ def test__parse_narrow_link(
         [
             "parsed_link",
             "is_user_subscribed_to_stream",
+            "is_valid_private_recipient",
             "is_valid_stream",
             "topics_in_stream",
             "expected_error",
@@ -624,6 +625,7 @@ def test__parse_narrow_link(
                 True,
                 None,
                 None,
+                None,
                 "",
                 id="valid_modern_stream_narrow_parsed_link",
             ),
@@ -635,6 +637,7 @@ def test__parse_narrow_link(
                 False,
                 None,
                 None,
+                None,
                 "The stream seems to be either unknown or unsubscribed",
                 id="invalid_modern_stream_narrow_parsed_link",
             ),
@@ -644,6 +647,7 @@ def test__parse_narrow_link(
                     stream=DecodedStream(stream_id=None, stream_name="Stream 1"),
                 ),
                 None,
+                None,
                 True,
                 None,
                 "",
@@ -655,6 +659,7 @@ def test__parse_narrow_link(
                     stream=DecodedStream(stream_id=None, stream_name="foo"),
                 ),
                 None,
+                None,
                 False,
                 None,
                 "The stream seems to be either unknown or unsubscribed",
@@ -668,6 +673,7 @@ def test__parse_narrow_link(
                 ),
                 True,
                 None,
+                None,
                 ["Valid"],
                 "",
                 id="valid_topic_narrow_parsed_link",
@@ -680,6 +686,7 @@ def test__parse_narrow_link(
                 ),
                 True,
                 None,
+                None,
                 [],
                 "Invalid topic name",
                 id="invalid_topic_narrow_parsed_link",
@@ -693,6 +700,7 @@ def test__parse_narrow_link(
                 True,
                 None,
                 None,
+                None,
                 "",
                 id="valid_stream_near_narrow_parsed_link",
             ),
@@ -705,6 +713,7 @@ def test__parse_narrow_link(
                 True,
                 None,
                 None,
+                None,
                 "Invalid message ID",
                 id="invalid_stream_near_narrow_parsed_link",
             ),
@@ -717,6 +726,7 @@ def test__parse_narrow_link(
                 ),
                 True,
                 None,
+                None,
                 ["Valid"],
                 "",
                 id="valid_topic_near_narrow_parsed_link",
@@ -730,6 +740,7 @@ def test__parse_narrow_link(
                 ),
                 True,
                 None,
+                None,
                 ["Valid"],
                 "Invalid message ID",
                 id="invalid_topic_near_narrow_parsed_link",
@@ -739,16 +750,107 @@ def test__parse_narrow_link(
                 None,
                 None,
                 None,
+                None,
                 "The narrow link seems to be either broken or unsupported",
                 id="invalid_narrow_link",
             ),
+            case(
+                ParsedNarrowLink(
+                    narrow="stream", stream=DecodedStream(stream_id=1, stream_name=None)
+                ),  # ...
+                True,
+                None,
+                None,
+                None,
+                "",
+                id="valid_stream_data_with_stream_id",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="stream",
+                    stream=DecodedStream(stream_id=462, stream_name=None),
+                ),  # ...
+                False,
+                None,
+                None,
+                None,
+                "The stream seems to be either unknown or unsubscribed",
+                id="invalid_stream_data_with_stream_id",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="stream",
+                    stream=DecodedStream(stream_id=None, stream_name="Stream 1"),
+                ),  # ...
+                None,
+                None,
+                True,
+                None,
+                "",
+                id="valid_stream_data_with_stream_name",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="stream",
+                    stream=DecodedStream(stream_id=None, stream_name="foo"),
+                ),  # ...
+                None,
+                None,
+                False,
+                None,
+                "The stream seems to be either unknown or unsubscribed",
+                id="invalid_stream_data_with_stream_name",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="pm_with",
+                    pm_with=DecodedPM(
+                        type=None, recipient_ids=[1001, 11], recipient_emails=None
+                    ),
+                ),  # ...
+                None,
+                True,
+                None,
+                None,
+                "",
+                id="valid_pm_data",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="pm_with",
+                    pm_with=DecodedPM(
+                        type=None, recipient_ids=[1001, 11, 12], recipient_emails=None
+                    ),
+                ),  # ...
+                None,
+                True,
+                None,
+                None,
+                "",
+                id="valid_group_pm_data",
+            ),
+            case(
+                ParsedNarrowLink(
+                    narrow="pm_with",
+                    pm_with=DecodedPM(
+                        type=None, recipient_ids=[1001, -1], recipient_emails=None
+                    ),
+                ),  # ...
+                None,
+                False,
+                None,
+                None,
+                "The PM has one or more invalid recipient(s)",
+                id="invalid_recipient",
+            ),
         ],
     )
     def test__validate_narrow_link(
         self,
         stream_dict: Dict[int, Any],
         parsed_link: ParsedNarrowLink,
         is_user_subscribed_to_stream: Optional[bool],
+        is_valid_private_recipient: Optional[bool],
         is_valid_stream: Optional[bool],
         topics_in_stream: Optional[List[str]],
         expected_error: str,
@@ -757,6 +859,9 @@ def test__validate_narrow_link(
         self.controller.model.is_user_subscribed_to_stream.return_value = (
             is_user_subscribed_to_stream
         )
+        self.controller.model.is_valid_private_recipient.return_value = (
+            is_valid_private_recipient
+        )
         self.controller.model.is_valid_stream.return_value = is_valid_stream
         self.controller.model.topics_in_stream.return_value = topics_in_stream
         mocked_button = self.message_link_button()

zulipterminal/ui_tools/buttons.py

@@ -505,6 +505,23 @@ def _validate_stream_data(self, parsed_link: ParsedNarrowLink) -> str:
 
         return ""
 
+    def _validate_pm_data(self, parsed_link: ParsedNarrowLink) -> str:
+        """
+        Validates PM data and returns either an empty string for a successful
+        validation or an appropriate validation error.
+        """
+        recipient_ids = parsed_link["pm_with"]["recipient_ids"]
+
+        for recipient_id in recipient_ids:
+            user = self.model._all_users_by_id.get(recipient_id, None)
+            email = user["email"] if user else ""
+            name = user["full_name"] if user else ""
+
+            if not self.model.is_valid_private_recipient(email, name):
+                return "The PM has one or more invalid recipient(s)"
+
+        return ""
+
     def _validate_narrow_link(self, parsed_link: ParsedNarrowLink) -> str:
         """
         Returns either an empty string for a successful validation or an
@@ -519,6 +536,12 @@ def _validate_narrow_link(self, parsed_link: ParsedNarrowLink) -> str:
             if error:
                 return error
 
+        # Validate PM data.
+        if "pm_with" in parsed_link:
+            error = self._validate_pm_data(parsed_link)
+            if error:
+                return error
+
         # Validate topic name.
         if "topic_name" in parsed_link:
             topic_name = parsed_link["topic_name"]