Improved displaying M2M delta changes

These lists are now stringified using `str()` instead of `repr()` on
each element.

Author: ddabble

simple_history/template_utils.py

@@ -107,6 +107,11 @@ def stringify_delta_change_value(self, change: ModelChange, value: Any) -> str:
         :param value: Either ``change.old`` or ``change.new``, as returned by
                ``prepare_delta_change_value()``.
         """
+        # If `value` is a list, stringify it using `str()` instead of `repr()`
+        # (the latter of which is the default when stringifying lists)
+        if isinstance(value, list):
+            value = f'[{", ".join(map(str, value))}]'
+
         value = conditional_escape(value)
         value = truncatechars_html(value, self.max_displayed_delta_change_chars)
         return value

simple_history/tests/tests/test_admin.py

@@ -176,8 +176,7 @@ def test_history_list_contains_diff_changes_for_m2m_fields(self):
         expected_old_places = "[]"
         self.assertNotContains(response, expected_old_places)
         expected_new_places = (
-            f"[<Place: Place object ({place1_pk})>,"
-            f" <Place: Place object ({place2_pk})>]"
+            f"[Place object ({place1_pk}), Place object ({place2_pk})]"
         )
         self.assertNotContains(response, expected_new_places)