no longer access source db obj in snippet

securedrop_client/gui/widgets.py

@@ -22,7 +22,7 @@
 import sys
 
 from gettext import gettext as _
-from typing import Dict, List, Union  # noqa: F401
+from typing import Dict, List, Union, Optional  # noqa: F401
 from uuid import uuid4
 from PyQt5.QtCore import Qt, pyqtSlot, pyqtSignal, QEvent, QTimer, QSize, pyqtBoundSignal, \
     QObject, QPoint
@@ -927,12 +927,12 @@ def update(self, sources: List[Source]) -> List[str]:
 
                 try:
                     del self.source_widgets[list_widget.source_uuid]
-                    deleted_uuids.append(list_widget.source_uuid)
                 except KeyError:
                     pass
-                finally:
-                    self.takeItem(i)
-                    list_widget.deleteLater()
+
+                self.takeItem(i)
+                deleted_uuids.append(list_widget.source_uuid)
+                list_widget.deleteLater()
 
         # Create new widgets for new sources
         widget_uuids = [self.itemWidget(self.item(i)).source_uuid for i in range(self.count())]
@@ -966,15 +966,35 @@ def get_current_source(self):
         if source_widget and source_exists(self.controller.session, source_widget.source_uuid):
             return source_widget.source
 
-    def set_snippet(self, source_uuid, message_uuid, content):
-        """
-        Given a UUID of a source, if the referenced message is the latest
-        message, then update the source's preview snippet to the referenced
-        content.
-        """
-        source_widget = self.source_widgets.get(source_uuid)
+    def get_source_widget(self, source_uuid: str) -> Optional[QListWidget]:
+        '''
+        First try to get the source widget from the cache, then look for it in the SourceList.
+        '''
+        try:
+            source_widget = self.source_widgets[source_uuid]
+            return source_widget
+        except KeyError:
+            pass
+
+        for i in range(self.count()):
+            list_item = self.item(i)
+            source_widget = self.itemWidget(list_item)
+            if source_widget and source_widget.source_uuid == source_uuid:
+                return source_widget
+
+        return None
+
+    @pyqtSlot(str, str, str)
+    def set_snippet(self, source_uuid: str, collection_item_uuid: str, content: str) -> None:
+        '''
+        Set the source widget's preview snippet with the supplied content.
+
+        Note: The signal's `collection_item_uuid` is not needed for setting the preview snippet. It
+        is used by other signal handlers.
+        '''
+        source_widget = self.get_source_widget(source_uuid)
         if source_widget:
-            source_widget.set_snippet(source_uuid, message_uuid, content)
+            source_widget.set_snippet(source_uuid, content)
 
 
 class SourceWidget(QWidget):
@@ -1145,37 +1165,28 @@ def update(self):
             self.controller.session.refresh(self.source)
             self.timestamp.setText(_(arrow.get(self.source.last_updated).format('DD MMM')))
             self.name.setText(self.source.journalist_designation)
-            self.set_snippet(self.source.uuid)
+
+            if not self.source.collection:
+                self.set_snippet(self.source_uuid, '')
+            else:
+                last_collection_obj = self.source.collection[-1]
+                self.set_snippet(self.source_uuid, str(last_collection_obj))
+
             if self.source.document_count == 0:
                 self.paperclip.hide()
             self.star.update()
         except sqlalchemy.exc.InvalidRequestError as e:
             logger.error(f"Could not update SourceWidget for source {self.source_uuid}: {e}")
             raise
 
-    def set_snippet(self, source: str, uuid: str = None, content: str = None):
+    def set_snippet(self, source_uuid: str, content: str):
         """
-        Update the preview snippet only if the new message is for the
-        referenced source and there's a source collection. If a uuid and
-        content are passed then use these, otherwise default to whatever the
-        latest item in the conversation might be.
+        Update the preview snippet if the source_uuid matches our own.
         """
-        if source != self.source_uuid:
+        if source_uuid != self.source_uuid:
             return
 
-        self.preview.setText("")
-
-        try:
-            self.controller.session.refresh(self.source)
-            if not self.source.collection:
-                return
-            last_collection_object = self.source.collection[-1]
-            if uuid == last_collection_object.uuid and content:
-                self.preview.setText(content)
-            else:
-                self.preview.setText(str(last_collection_object))
-        except sqlalchemy.exc.InvalidRequestError as e:
-            logger.error(f"Could not update snippet for source {self.source_uuid}: {e}")
+        self.preview.setText(content)
 
     def delete_source(self, event):
         if self.controller.api is None:

tests/gui/test_widgets.py

@@ -1,7 +1,6 @@
 """
 Make sure the UI widgets are configured correctly and work as expected.
 """
-import re
 import pytest
 import arrow
 from datetime import datetime
@@ -950,7 +949,40 @@ def test_SourceList_set_snippet(mocker):
         "a_uuid": mock_widget,
     }
     sl.set_snippet("a_uuid", "msg_uuid", "msg_content")
-    mock_widget.set_snippet.assert_called_once_with("a_uuid", "msg_uuid", "msg_content")
+    mock_widget.set_snippet.assert_called_once_with("a_uuid", "msg_content")
+
+
+def test_SourceList_get_source_widget(mocker):
+    sl = SourceList()
+    sl.controller = mocker.MagicMock()
+    mock_source = factory.Source(uuid='mock_uuid')
+    sl.update([mock_source])
+    sl.source_widgets = {}
+
+    source_widget = sl.get_source_widget('mock_uuid')
+
+    assert source_widget.source_uuid == 'mock_uuid'
+    assert source_widget == sl.itemWidget(sl.item(0))
+
+
+def test_SourceList_get_source_widget_does_not_exist(mocker):
+    sl = SourceList()
+    sl.controller = mocker.MagicMock()
+    mock_source = factory.Source(uuid='mock_uuid')
+    sl.update([mock_source])
+    sl.source_widgets = {}
+
+    source_widget = sl.get_source_widget('uuid_for_source_not_in_list')
+
+    assert source_widget is None
+
+
+def test_SourceList_get_source_widget_if_one_exists_in_cache(mocker):
+    sl = SourceList()
+    mock_source_widget = factory.Source(uuid='mock_uuid')
+    sl.source_widgets = {'mock_uuid': mock_source_widget}
+    source_widget = sl.get_source_widget('mock_uuid')
+    assert source_widget == mock_source_widget
 
 
 def test_SourceWidget_init(mocker):
@@ -1013,29 +1045,19 @@ def test_SourceWidget_set_snippet(mocker, session_maker, session, homedir):
     session.commit()
 
     sw = SourceWidget(controller, source)
-    sw.set_snippet(source.uuid, f.uuid, f.filename)
+    sw.set_snippet(source.uuid, f.filename)
     assert sw.preview.text() == f.filename
 
     # check when a different source is specified
-    sw.set_snippet("not-the-source-uuid", f.uuid, "something new")
+    sw.set_snippet("not-the-source-uuid", "something new")
     assert sw.preview.text() == f.filename
 
-    # check when the source has been deleted
     source_uuid = source.uuid
     session.delete(source)
     session.commit()
-    error_logger = mocker.patch("securedrop_client.gui.widgets.logger.error")
-    sw.set_snippet(source_uuid, "some-uuid", "something new")
-    error_logger.assert_called_once()
-    assert re.match(
-        (
-            f"Could not update snippet for source {source_uuid}: "
-            "Instance '<Source at 0x[0-9a-f]+>' is not persistent within this Session"
-        ),
-        error_logger.call_args_list[0][0][0],
-    )
 
-    assert sw.preview.text() == ""
+    # check when the source has been deleted that it catches sqlalchemy.exc.InvalidRequestError
+    sw.set_snippet(source_uuid, "something new")
 
 
 def test_SourceWidget_update_truncate_latest_msg(mocker):