edit_readthrough: set start_date/finish_date iff present in request

Fixes: #3164

bookwyrm/tests/views/test_status.py

@@ -1,6 +1,5 @@
 """ test for app action functionality """
 import json
-from unittest import expectedFailure
 from unittest.mock import patch
 import dateutil
 from django.core.exceptions import PermissionDenied
@@ -170,7 +169,6 @@ def test_create_status_rating(self, *_):
         self.assertEqual(status.rating, 4.0)
         self.assertIsNone(status.edited_date)
 
-    @expectedFailure  # https://github.com/bookwyrm-social/bookwyrm/issues/3164
     def test_create_status_progress(self, *_):
         """create a status that updates a readthrough"""
         start_date = timezone.make_aware(dateutil.parser.parse("2024-07-27"))
@@ -200,7 +198,7 @@ def test_create_status_progress(self, *_):
         readthrough.refresh_from_db()
 
         self.assertEqual(1, readthrough.progress)
-        self.assertEqual(start_date, readthrough.start_date)
+        self.assertEqual(start_date, readthrough.start_date)  # not overwritten
 
     def test_create_status_wrong_user(self, *_):
         """You can't compose statuses for someone else"""

bookwyrm/views/status.py

@@ -201,12 +201,11 @@ def edit_readthrough(request):
     # TODO: remove this, it duplicates the code in the ReadThrough view
     readthrough = get_object_or_404(models.ReadThrough, id=request.POST.get("id"))
 
-    readthrough.start_date = load_date_in_user_tz_as_utc(
-        request.POST.get("start_date"), request.user
-    )
-    readthrough.finish_date = load_date_in_user_tz_as_utc(
-        request.POST.get("finish_date"), request.user
-    )
+    if start_date := request.POST.get("start_date"):
+        readthrough.start_date = load_date_in_user_tz_as_utc(start_date, request.user)
+
+    if finish_date := request.POST.get("finish_date"):
+        readthrough.finish_date = load_date_in_user_tz_as_utc(finish_date, request.user)
 
     progress = request.POST.get("progress")
     try: