refactor: model: Type recipients as List[str] in send_private_message.

Currently, the send_private_message() method expects a str for the
recipients parameter. This commit modifies it to List[str] and also
adds a check against an empty recipient list by raising a Runtime Error.

Tests updated.

Author: prah23

tests/model/test_model.py

@@ -438,10 +438,13 @@ def test_react_to_message_for_not_thumbs_up(self, model):
         ({'result': 'success'}, True),
         ({'result': 'some_failure'}, False),
     ])
+    @pytest.mark.parametrize('recipients', [
+        ['[email protected]'],
+        ['[email protected]', '[email protected]']
+    ])
     def test_send_private_message(self, mocker, model,
-                                  response, return_value,
-                                  content="hi!",
-                                  recipients="[email protected]"):
+                                  recipients, response, return_value,
+                                  content="hi!"):
         self.client.send_message = mocker.Mock(return_value=response)
 
         result = model.send_private_message(recipients, content)
@@ -453,6 +456,12 @@ def test_send_private_message(self, mocker, model,
         self.display_error_if_present.assert_called_once_with(response,
                                                               self.controller)
 
+    def test_send_private_message_with_no_recipients(self, model,
+                                                     content="hi!",
+                                                     recipients=[]):
+        with pytest.raises(RuntimeError):
+            model.send_private_message(recipients, content)
+
     @pytest.mark.parametrize('response, return_value', [
         ({'result': 'success'}, True),
         ({'result': 'some_failure'}, False),

zulipterminal/model.py

@@ -333,16 +333,19 @@ def mark_message_ids_as_read(self, id_list: List[int]) -> None:
         })
         display_error_if_present(response, self.controller)
 
-    def send_private_message(self, recipients: str,
+    def send_private_message(self, recipients: List[str],
                              content: str) -> bool:
-        request = {
-            'type': 'private',
-            'to': recipients,
-            'content': content,
-        }
-        response = self.client.send_message(request)
-        display_error_if_present(response, self.controller)
-        return response['result'] == 'success'
+        if recipients:
+            request = {
+                'type': 'private',
+                'to': recipients,
+                'content': content,
+            }
+            response = self.client.send_message(request)
+            display_error_if_present(response, self.controller)
+            return response['result'] == 'success'
+        else:
+            raise RuntimeError('Empty recipients list.')
 
     def send_stream_message(self, stream: str, topic: str,
                             content: str) -> bool:

zulipterminal/ui_tools/boxes.py

@@ -378,8 +378,10 @@ def keypress(self, size: urwid_Size, key: str) -> Optional[str]:
                         msg_id=self.msg_edit_id,
                     )
                 else:
+                    recipient_emails = [email.strip() for email in
+                                        self.to_write_box.edit_text.split(',')]
                     success = self.model.send_private_message(
-                        recipients=self.to_write_box.edit_text,
+                        recipients=recipient_emails,
                         content=self.msg_write_box.edit_text
                     )
             if success: