diff --git a/backend/geonature/tests/test_synthese.py b/backend/geonature/tests/test_synthese.py
index 83fe452798..e737bcd48b 100644
--- a/backend/geonature/tests/test_synthese.py
+++ b/backend/geonature/tests/test_synthese.py
@@ -1226,40 +1226,100 @@ def test_get_one_synthese_record(self, app, users, synthese_data):
         assert response.status_code == Forbidden.code
 
     def test_taxon_observer(self, synthese_data, users):
-        set_logged_user(self.client, users["stranger_user"])
+        set_logged_user(self.client, users["admin_user"])
 
         SORT_ORDER_UNDEFINED = "sort-order-undefined"
         SORT_ORDER_ASC = "asc"
         SORT_ORDER_DESC = "desc"
+        PER_PAGE = 2
         SORT_BY_UNDEFINED = "sort-by-undefined"
 
         CD_REF = 2497
-        CD_REF_OBSERVERS = {
+        CD_REF_OBSERVERS_ASC = {
             "items": [
                 {
-                    "date_max": "Thu, 03 Oct 2024 08:09:10 GMT",
+                    "date_max": "Mon, 20 May 2019 00:00:00 GMT",
+                    "date_min": "Mon, 20 May 2019 00:00:00 GMT",
+                    "media_count": 0,
+                    "observation_count": 1,
+                    "observer": "Albert Christophe",
+                },
+                {
+                    "date_max": "Fri, 04 Oct 2024 17:04:09 GMT",
                     "date_min": "Wed, 02 Oct 2024 11:22:33 GMT",
                     "media_count": 0,
+                    "observation_count": 4,
+                    "observer": "Bob Bobby",
+                },
+            ],
+            "total": 8,
+            "per_page": 2,
+            "page": 1,
+        }
+        CD_REF_OBSERVERS_DESC = {
+            "items": [
+                {
+                    "date_max": "Sat, 20 Apr 2019 00:00:00 GMT",
+                    "date_min": "Thu, 08 Sep 2016 00:00:00 GMT",
+                    "media_count": 0,
                     "observation_count": 3,
-                    "observer": "Bobby Bob",
-                }
+                    "observer": "Rippert Laurent",
+                },
+                {
+                    "date_max": "Sat, 20 Apr 2019 00:00:00 GMT",
+                    "date_min": "Sat, 20 Apr 2019 00:00:00 GMT",
+                    "media_count": 0,
+                    "observation_count": 1,
+                    "observer": "Lecuyer Clément",
+                },
             ],
-            "total": 2,
-            "per_page": 1,
             "page": 1,
+            "per_page": 2,
+            "total": 8,
         }
 
         # Unknow sort_order parameters: shoudl fallback in asc
         response = self.client.get(
-            url_for("gn_synthese.taxon_observers", cd_ref=CD_REF, sort_order=SORT_ORDER_UNDEFINED),
+            url_for(
+                "gn_synthese.taxon_observers",
+                cd_ref=CD_REF,
+                per_page=PER_PAGE,
+                sort_order=SORT_ORDER_UNDEFINED,
+            ),
         )
         assert response.status_code == 200
+        assert response.get_json() == CD_REF_OBSERVERS_ASC
+
+        # Sort order ASC
+        response = self.client.get(
+            url_for(
+                "gn_synthese.taxon_observers",
+                cd_ref=CD_REF,
+                per_page=PER_PAGE,
+                sort_order=SORT_ORDER_ASC,
+            ),
+        )
+        assert response.status_code == 200
+        assert response.get_json() == CD_REF_OBSERVERS_ASC
+
+        # Sort order DESC
+        response = self.client.get(
+            url_for(
+                "gn_synthese.taxon_observers",
+                cd_ref=CD_REF,
+                per_page=PER_PAGE,
+                sort_order=SORT_ORDER_DESC,
+            ),
+        )
+        assert response.status_code == 200
+        assert response.get_json() == CD_REF_OBSERVERS_DESC
 
         # Unknow sort_by parameters
         response = self.client.get(
             url_for(
                 "gn_synthese.taxon_observers",
                 cd_ref=CD_REF,
+                per_page=PER_PAGE,
                 sort_order=SORT_ORDER_ASC,
                 sort_by=SORT_BY_UNDEFINED,
             ),
@@ -1269,13 +1329,17 @@ def test_taxon_observer(self, synthese_data, users):
             response.json["description"] == f"The sort_by column {SORT_BY_UNDEFINED} is not defined"
         )
 
-        # Missing area_type parameter
+        # Everything is fine
         response = self.client.get(
-            url_for("gn_synthese.taxon_observers", cd_ref=CD_REF),
+            url_for(
+                "gn_synthese.taxon_observers",
+                cd_ref=CD_REF,
+                per_page=PER_PAGE,
+            )
         )
 
         assert response.status_code == 200
-        assert response.get_json() == CD_REF_OBSERVERS
+        assert response.get_json() == CD_REF_OBSERVERS_ASC
 
     def test_color_taxon(self, synthese_data, users):
         # Note: require grids 5×5!