refactor: model/views: Use get_subscription_email instead of stream_dict.

This commit replaces the usage of directly indexing stream_dict for
"email_address" data with the new stream property accessor method
"get_subscription_email".

Test added.

Author: theViz343

tests/model/test_model.py

@@ -2294,6 +2294,45 @@ def test_get_subscription_color(
         model.stream_dict = stream_dict
         assert model.get_subscription_color(stream_id) == expected_value
 
+    @pytest.mark.parametrize(
+        "stream_id, expected_value",
+        [
+            case(
+                1000,
+                "[email protected]",
+            ),
+            case(
+                3,
+                "[email protected]",
+            ),
+        ],
+    )
+    def test_get_subscription_email(
+        self,
+        model,
+        stream_dict,
+        unsubscribed_streams_fixture,
+        stream_id,
+        expected_value,
+    ):
+        model.stream_dict = stream_dict
+        model._unsubscribed_streams = unsubscribed_streams_fixture
+        assert model.get_subscription_email(stream_id) == expected_value
+
+    def test_get_subscription_email_not_subscribed(
+        self,
+        model,
+        stream_dict,
+        unsubscribed_streams_fixture,
+        stream_id=5,
+    ):
+        model.stream_dict = stream_dict
+        model._unsubscribed_streams = unsubscribed_streams_fixture
+        with pytest.raises(
+            RuntimeError, match=f"Stream with id {stream_id} is not subscribed to!"
+        ):
+            model.get_subscription_email(stream_id)
+
     def test_get_all_subscription_ids(
         self,
         model,

zulipterminal/model.py

@@ -1243,6 +1243,14 @@ def get_subscription_color(self, stream_id: int) -> Optional[str]:
             return self._unsubscribed_streams[stream_id]["color"]
         return None
 
+    def get_subscription_email(self, stream_id: int) -> Optional[str]:
+        if stream_id in self.stream_dict:
+            return self.stream_dict[stream_id]["email_address"]
+        elif stream_id in self._unsubscribed_streams:
+            return self._unsubscribed_streams[stream_id]["email_address"]
+        else:
+            raise RuntimeError(f"Stream with id {stream_id} is not subscribed to!")
+
     def _subscribe_to_streams(self, subscriptions: List[Subscription]) -> None:
         def make_reduced_stream_data(stream: Subscription) -> StreamData:
             # stream_id has been changed to id.

zulipterminal/ui_tools/views.py

@@ -1314,7 +1314,7 @@ def __init__(self, controller: Any, stream_id: int) -> None:
             else "Not Public to Users"
         )
         member_keys = ", ".join(map(repr, keys_for_command("STREAM_MEMBERS")))
-        self.stream_email = stream["email_address"]
+        self.stream_email = controller.model.get_subscription_email(self.stream_id)
         email_keys = ", ".join(map(repr, keys_for_command("COPY_STREAM_EMAIL")))
 
         weekly_traffic = controller.model.get_stream_weekly_traffic(self.stream_id)