Imrpvoe the case links

atlas/tests/test_priors_futures.py

@@ -131,3 +131,58 @@ def test_case_prior_and_future_relation_post(client, make_case):
     )
     assert response_remove.status_code == 200
     assert not CasePrior.objects.filter(casedetail=casedetail, prior_case=case3).exists()
+
+
+@pytest.mark.django_db
+def test_linked_cases_reordering(client, make_case):
+    # Setup user
+    user = get_user_model().objects.create_user(
+        username="author_user_reorder", password="password", email="author_reorder@test.com"
+    )
+    
+    case1 = make_case(title="Case A")
+    case2 = make_case(title="Case B")
+    case3 = make_case(title="Case C")
+
+    # Author permissions
+    case1.author.add(user)
+    case2.author.add(user)
+    case3.author.add(user)
+
+    # Initial order: case1 -> case2 -> case3
+    case2.previous_case = case1
+    case2.save(update_fields=["previous_case"])
+    case3.previous_case = case2
+    case3.save(update_fields=["previous_case"])
+
+    client.force_login(user)
+    url = reverse("atlas:linked_cases_overview", kwargs={"case_id": case2.pk})
+
+    # Verify GET works and shows reorder editor when requested
+    response_get = client.get(url + "?show_reorder=1")
+    assert response_get.status_code == 200
+    assert "Reorder Cases" in response_get.content.decode("utf-8")
+
+    # Post new order: case3 -> case1 -> case2
+    response_post = client.post(
+        url,
+        data={
+            "form_action": "reorder_cases",
+            "case_order_0": case3.pk,
+            "case_order_1": case1.pk,
+            "case_order_2": case2.pk,
+        },
+        follow=True,
+    )
+    assert response_post.status_code == 200
+
+    # Refresh cases from database
+    case1.refresh_from_db()
+    case2.refresh_from_db()
+    case3.refresh_from_db()
+
+    # Verify new order in DB: case3 -> case1 -> case2
+    assert case3.previous_case is None
+    assert case1.previous_case == case3
+    assert case2.previous_case == case1
+