diff --git a/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py b/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
index 9be78332f3..4cda0b4027 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
@@ -11,6 +11,7 @@
 from antarest.core.utils.utils import StopWatch
 from antarest.study.storage.rawstudy.model.filesystem.config.model import FileStudyTreeConfig
 from antarest.study.storage.rawstudy.model.filesystem.context import ContextServer
+from antarest.study.storage.rawstudy.model.filesystem.folder_node import ChildNotFoundError
 from antarest.study.storage.rawstudy.model.filesystem.matrix.matrix import MatrixFrequency, MatrixNode
 
 logger = logging.getLogger(__name__)
@@ -49,23 +50,28 @@ def parse(
         try:
             # sourcery skip: extract-method
             stopwatch = StopWatch()
-            if self.get_link_path().exists():
-                link = self.get_link_path().read_text()
+            link_path = self.get_link_path()
+            if link_path.exists():
+                link = link_path.read_text()
                 matrix_json = self.context.resolver.resolve(link)
                 matrix_json = cast(JSON, matrix_json)
-                matrix: pd.DataFrame = pd.DataFrame(
-                    data=matrix_json["data"],
-                    columns=matrix_json["columns"],
-                    index=matrix_json["index"],
-                )
+                matrix: pd.DataFrame = pd.DataFrame(**matrix_json)
             else:
-                matrix = pd.read_csv(
-                    file_path,
-                    sep="\t",
-                    dtype=float,
-                    header=None,
-                    float_precision="legacy",
-                )
+                try:
+                    matrix = pd.read_csv(
+                        file_path,
+                        sep="\t",
+                        dtype=float,
+                        header=None,
+                        float_precision="legacy",
+                    )
+                except FileNotFoundError as e:
+                    # Raise 404 'Not Found' if the TSV file is not found
+                    logger.warning(f"Matrix file'{file_path}' not found")
+                    study_id = self.config.study_id
+                    relpath = file_path.relative_to(self.config.study_path).as_posix()
+                    raise ChildNotFoundError(f"File '{relpath}' not found in the study '{study_id}'") from e
+
             stopwatch.log_elapsed(lambda x: logger.info(f"Matrix parsed in {x}s"))
             matrix.dropna(how="any", axis=1, inplace=True)
             if return_dataframe:
diff --git a/antarest/study/storage/rawstudy/model/filesystem/matrix/output_series_matrix.py b/antarest/study/storage/rawstudy/model/filesystem/matrix/output_series_matrix.py
index 6f82eaab34..dbc3c4385e 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/matrix/output_series_matrix.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/matrix/output_series_matrix.py
@@ -50,6 +50,7 @@ def get_lazy_content(
         depth: int = -1,
         expanded: bool = False,
     ) -> str:
+        # noinspection SpellCheckingInspection
         return f"matrixfile://{self.config.path.name}"
 
     def parse_dataframe(
@@ -58,14 +59,21 @@ def parse_dataframe(
         tmp_dir: Any = None,
     ) -> DataFrame:
         file_path = file_path or self.config.path
-        df = pd.read_csv(
-            file_path,
-            sep="\t",
-            skiprows=4,
-            header=[0, 1, 2],
-            na_values="N/A",
-            float_precision="legacy",
-        )
+        try:
+            df = pd.read_csv(
+                file_path,
+                sep="\t",
+                skiprows=4,
+                header=[0, 1, 2],
+                na_values="N/A",
+                float_precision="legacy",
+            )
+        except FileNotFoundError as e:
+            # Raise 404 'Not Found' if the TSV file is not found
+            logger.warning(f"Matrix file'{file_path}' not found")
+            study_id = self.config.study_id
+            relpath = file_path.relative_to(self.config.study_path).as_posix()
+            raise ChildNotFoundError(f"File '{relpath}' not found in the study '{study_id}'") from e
 
         if tmp_dir:
             tmp_dir.cleanup()
diff --git a/tests/integration/study_data_blueprint/test_binding_constraints.py b/tests/integration/study_data_blueprint/test_binding_constraints.py
index af537fcc7f..7e3c613e16 100644
--- a/tests/integration/study_data_blueprint/test_binding_constraints.py
+++ b/tests/integration/study_data_blueprint/test_binding_constraints.py
@@ -46,6 +46,7 @@ def test_constraint_id__link(self) -> None:
             offset=123,
             data=LinkTerm(area1="Area 1", area2="Area 2"),
         )
+        assert term.data is not None
         assert term.generate_id() == term.data.generate_id()
 
     def test_constraint_id__cluster(self) -> None:
@@ -55,6 +56,7 @@ def test_constraint_id__cluster(self) -> None:
             offset=123,
             data=ClusterTerm(area="Area 1", cluster="Cluster X"),
         )
+        assert term.data is not None
         assert term.generate_id() == term.data.generate_id()
 
     def test_constraint_id__other(self) -> None:
@@ -66,18 +68,11 @@ def test_constraint_id__other(self) -> None:
         assert term.generate_id() == "foo"
 
 
-def _upload_matrix(
-    client: TestClient, user_access_token: str, study_id: str, matrix_path: str, df: pd.DataFrame
-) -> None:
+def _upload_matrix(client: TestClient, study_id: str, matrix_path: str, df: pd.DataFrame) -> None:
     tsv = io.BytesIO()
     df.to_csv(tsv, sep="\t", index=False, header=False)
     tsv.seek(0)
-    res = client.put(
-        f"/v1/studies/{study_id}/raw",
-        params={"path": matrix_path},
-        headers={"Authorization": f"Bearer {user_access_token}"},
-        files={"file": tsv},
-    )
+    res = client.put(f"/v1/studies/{study_id}/raw", params={"path": matrix_path}, files={"file": tsv})
     res.raise_for_status()
 
 
@@ -89,72 +84,43 @@ class TestBindingConstraints:
 
     @pytest.mark.parametrize("study_type", ["raw", "variant"])
     def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, study_type: str) -> None:
-        user_headers = {"Authorization": f"Bearer {user_access_token}"}
+        client.headers = {"Authorization": f"Bearer {user_access_token}"}  # type: ignore
 
         # =============================
         #  STUDY PREPARATION
         # =============================
 
         # Create a Study
-        res = client.post(
-            "/v1/studies",
-            headers=user_headers,
-            params={"name": "foo", "version": "860"},
-        )
+        res = client.post("/v1/studies", params={"name": "foo", "version": "860"})
         assert res.status_code == 201, res.json()
         study_id = res.json()
 
         # Create Areas
-        res = client.post(
-            f"/v1/studies/{study_id}/areas",
-            headers=user_headers,
-            json={
-                "name": "Area 1",
-                "type": "AREA",
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/areas", json={"name": "Area 1", "type": "AREA"})
         assert res.status_code == 200, res.json()
         area1_id = res.json()["id"]
         assert area1_id == "area 1"
 
-        res = client.post(
-            f"/v1/studies/{study_id}/areas",
-            headers=user_headers,
-            json={
-                "name": "Area 2",
-                "type": "AREA",
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/areas", json={"name": "Area 2", "type": "AREA"})
         assert res.status_code == 200, res.json()
         area2_id = res.json()["id"]
         assert area2_id == "area 2"
 
         # Create a link between the two areas
-        res = client.post(
-            f"/v1/studies/{study_id}/links",
-            headers=user_headers,
-            json={
-                "area1": area1_id,
-                "area2": area2_id,
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/links", json={"area1": area1_id, "area2": area2_id})
         assert res.status_code == 200, res.json()
 
         # Create a cluster in area1
         res = client.post(
             f"/v1/studies/{study_id}/areas/{area1_id}/clusters/thermal",
-            headers=user_headers,
-            json={
-                "name": "Cluster 1",
-                "group": "Nuclear",
-            },
+            json={"name": "Cluster 1", "group": "Nuclear"},
         )
         assert res.status_code == 200, res.json()
         cluster_id = res.json()["id"]
         assert cluster_id == "Cluster 1"
 
         # Get clusters list to check created cluster in area1
-        res = client.get(f"/v1/studies/{study_id}/areas/{area1_id}/clusters/thermal", headers=user_headers)
+        res = client.get(f"/v1/studies/{study_id}/areas/{area1_id}/clusters/thermal")
         clusters_list = res.json()
         assert res.status_code == 200, res.json()
         assert len(clusters_list) == 1
@@ -164,11 +130,7 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
 
         if study_type == "variant":
             # Create Variant
-            res = client.post(
-                f"/v1/studies/{study_id}/variants",
-                headers=user_headers,
-                params={"name": "Variant 1"},
-            )
+            res = client.post(f"/v1/studies/{study_id}/variants", params={"name": "Variant 1"})
             assert res.status_code in {200, 201}, res.json()
             study_id = res.json()
 
@@ -192,7 +154,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                     },
                 }
             ],
-            headers=user_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
@@ -211,7 +172,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                     },
                 }
             ],
-            headers=user_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
@@ -226,12 +186,11 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "terms": [],
                 "comments": "New API",
             },
-            headers=user_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
         # Get Binding Constraint list
-        res = client.get(f"/v1/studies/{study_id}/bindingconstraints", headers=user_headers)
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints")
         binding_constraints_list = res.json()
         assert res.status_code == 200, res.json()
         assert len(binding_constraints_list) == 3
@@ -278,7 +237,7 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         bc_id = binding_constraints_list[0]["id"]
 
         # Asserts binding constraint configuration is valid.
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups", headers=user_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups")
         assert res.status_code == 200, res.json()
 
         # =============================
@@ -293,7 +252,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "offset": 2,
                 "data": {"area1": area1_id, "area2": area2_id},
             },
-            headers=user_headers,
         )
         assert res.status_code == 200, res.json()
 
@@ -303,21 +261,14 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
             json={
                 "weight": 1,
                 "offset": 2,
-                "data": {
-                    "area": area1_id,
-                    "cluster": cluster_id,
-                },
-                # NOTE: cluster_id in term data can be uppercase, but it must be lowercase in the returned ini configuration file
+                "data": {"area": area1_id, "cluster": cluster_id},
+                # NOTE: cluster_id in term data can be uppercase, but it must be lowercase in the INI file
             },
-            headers=user_headers,
         )
         assert res.status_code == 200, res.json()
 
         # Get binding constraints list to check added terms
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            headers=user_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -340,19 +291,12 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         # Update constraint cluster term with uppercase cluster_id
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id}/term",
-            json={
-                "id": f"{area1_id}.{cluster_id}",
-                "weight": 3,
-            },
-            headers=user_headers,
+            json={"id": f"{area1_id}.{cluster_id}", "weight": 3},
         )
         assert res.status_code == 200, res.json()
 
         # Check updated terms, cluster_id should be lowercase in the returned configuration
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            headers=user_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -376,7 +320,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id}/term",
             json={"id": f"{area1_id}.!!invalid#cluster%%", "weight": 4},
-            headers=user_headers,
         )
         assert res.status_code == 404, res.json()
         exception = res.json()["exception"]
@@ -388,11 +331,7 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         # Update constraint cluster term with empty data
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id}/term",
-            json={
-                "id": f"{area1_id}.{cluster_id}",
-                "data": {},
-            },
-            headers=user_headers,
+            json={"id": f"{area1_id}.{cluster_id}", "data": {}},
         )
         assert res.status_code == 422, res.json()
         assert res.json() == {
@@ -402,17 +341,11 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         }
 
         # Remove Constraint term
-        res = client.delete(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}/term/{area1_id}%{area2_id}",
-            headers=user_headers,
-        )
+        res = client.delete(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}/term/{area1_id}%{area2_id}")
         assert res.status_code == 200, res.json()
 
         # Check updated terms, the deleted term should no longer exist.
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            headers=user_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -427,17 +360,10 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         assert constraint_terms == expected
 
         # Update random field, shouldn't remove the term.
-        res = client.put(
-            f"v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            json={"enabled": False},
-            headers=user_headers,
-        )
+        res = client.put(f"v1/studies/{study_id}/bindingconstraints/{bc_id}", json={"enabled": False})
         assert res.status_code == 200, res.json()
 
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            headers=user_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -449,27 +375,19 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
 
         # Update element of Binding constraint
         new_comment = "We made it !"
-        res = client.put(
-            f"v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            json={"comments": new_comment},
-            headers=user_headers,
-        )
+        res = client.put(f"v1/studies/{study_id}/bindingconstraints/{bc_id}", json={"comments": new_comment})
         assert res.status_code == 200
         assert res.json()["comments"] == new_comment
 
         # The user change the timeStep to daily instead of hourly.
         # We must check that the matrix is a daily/weekly matrix.
-        res = client.put(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id}",
-            json={"timeStep": "daily"},
-            headers=user_headers,
-        )
+        res = client.put(f"/v1/studies/{study_id}/bindingconstraints/{bc_id}", json={"timeStep": "daily"})
         assert res.status_code == 200, res.json()
         assert res.json()["timeStep"] == "daily"
 
         # Check that the command corresponds to a change in `time_step`
         if study_type == "variant":
-            res = client.get(f"/v1/studies/{study_id}/commands", headers=user_headers)
+            res = client.get(f"/v1/studies/{study_id}/commands")
             commands = res.json()
             args = commands[-1]["args"]
             assert args["time_step"] == "daily"
@@ -479,7 +397,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         res = client.get(
             f"/v1/studies/{study_id}/raw",
             params={"path": f"input/bindingconstraints/{bc_id}", "depth": 1, "formatted": True},  # type: ignore
-            headers=user_headers,
         )
         assert res.status_code == 200, res.json()
         dataframe = res.json()
@@ -501,7 +418,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "terms": [],
                 "comments": "New API",
             },
-            headers=user_headers,
         )
         assert res.status_code == 400, res.json()
         assert res.json() == {
@@ -520,7 +436,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "terms": [],
                 "comments": "New API",
             },
-            headers=user_headers,
         )
         assert res.status_code == 400, res.json()
         assert res.json() == {
@@ -539,7 +454,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "terms": [],
                 "comments": "",
             },
-            headers=user_headers,
         )
         assert res.status_code == 409, res.json()
 
@@ -556,7 +470,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "values": [[]],
                 "less_term_matrix": [[]],
             },
-            headers=user_headers,
         )
         assert res.status_code == 422, res.json()
         description = res.json()["description"]
@@ -577,7 +490,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
                 "comments": "Incoherent matrix with version",
                 "lessTermMatrix": [[]],
             },
-            headers=user_headers,
         )
         assert res.status_code == 422, res.json()
         description = res.json()["description"]
@@ -594,11 +506,7 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
             "comments": "Creation with matrix",
             "values": wrong_matrix.tolist(),
         }
-        res = client.post(
-            f"/v1/studies/{study_id}/bindingconstraints",
-            json=wrong_request_args,
-            headers=user_headers,
-        )
+        res = client.post(f"/v1/studies/{study_id}/bindingconstraints", json=wrong_request_args)
         assert res.status_code == 422, res.json()
         exception = res.json()["exception"]
         description = res.json()["description"]
@@ -607,7 +515,7 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         assert "(366, 3)" in description
 
         # Delete a fake binding constraint
-        res = client.delete(f"/v1/studies/{study_id}/bindingconstraints/fake_bc", headers=user_headers)
+        res = client.delete(f"/v1/studies/{study_id}/bindingconstraints/fake_bc")
         assert res.status_code == 404, res.json()
         assert res.json()["exception"] == "BindingConstraintNotFound"
         assert res.json()["description"] == "Binding constraint 'fake_bc' not found"
@@ -617,7 +525,6 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/binding_constraint_2",
             json={"group": grp_name},
-            headers=user_headers,
         )
         assert res.status_code == 422, res.json()
         assert res.json()["exception"] == "InvalidFieldForVersionError"
@@ -630,82 +537,48 @@ def test_lifecycle__nominal(self, client: TestClient, user_access_token: str, st
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/binding_constraint_2",
             json={"less_term_matrix": [[]]},
-            headers=user_headers,
         )
         assert res.status_code == 422, res.json()
         assert res.json()["exception"] == "InvalidFieldForVersionError"
         assert res.json()["description"] == "You cannot fill a 'matrix_term' as these values refer to v8.7+ studies"
 
     @pytest.mark.parametrize("study_type", ["raw", "variant"])
-    def test_for_version_870(self, client: TestClient, admin_access_token: str, study_type: str) -> None:
-        admin_headers = {"Authorization": f"Bearer {admin_access_token}"}
+    def test_for_version_870(self, client: TestClient, user_access_token: str, study_type: str) -> None:
+        client.headers = {"Authorization": f"Bearer {user_access_token}"}  # type: ignore
 
         # =============================
         #  STUDY PREPARATION
         # =============================
 
-        res = client.post(
-            "/v1/studies",
-            headers=admin_headers,
-            params={"name": "foo"},
-        )
+        res = client.post("/v1/studies", params={"name": "foo"})
         assert res.status_code == 201, res.json()
         study_id = res.json()
 
         if study_type == "variant":
             # Create Variant
-            res = client.post(
-                f"/v1/studies/{study_id}/variants",
-                headers=admin_headers,
-                params={"name": "Variant 1"},
-            )
+            res = client.post(f"/v1/studies/{study_id}/variants", params={"name": "Variant 1"})
             assert res.status_code in {200, 201}
             study_id = res.json()
 
         # Create Areas
-        res = client.post(
-            f"/v1/studies/{study_id}/areas",
-            headers=admin_headers,
-            json={
-                "name": "Area 1",
-                "type": "AREA",
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/areas", json={"name": "Area 1", "type": "AREA"})
         assert res.status_code == 200, res.json()
         area1_id = res.json()["id"]
         assert area1_id == "area 1"
 
-        res = client.post(
-            f"/v1/studies/{study_id}/areas",
-            headers=admin_headers,
-            json={
-                "name": "Area 2",
-                "type": "AREA",
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/areas", json={"name": "Area 2", "type": "AREA"})
         assert res.status_code == 200, res.json()
         area2_id = res.json()["id"]
         assert area2_id == "area 2"
 
         # Create a link between the two areas
-        res = client.post(
-            f"/v1/studies/{study_id}/links",
-            headers=admin_headers,
-            json={
-                "area1": area1_id,
-                "area2": area2_id,
-            },
-        )
+        res = client.post(f"/v1/studies/{study_id}/links", json={"area1": area1_id, "area2": area2_id})
         assert res.status_code == 200, res.json()
 
         # Create a cluster in area1
         res = client.post(
             f"/v1/studies/{study_id}/areas/{area1_id}/clusters/thermal",
-            headers=admin_headers,
-            json={
-                "name": "Cluster 1",
-                "group": "Nuclear",
-            },
+            json={"name": "Cluster 1", "group": "Nuclear"},
         )
         assert res.status_code == 200, res.json()
         cluster_id = res.json()["id"]
@@ -718,11 +591,7 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         # Creation of a bc without group
         bc_id_wo_group = "binding_constraint_1"
         args = {"enabled": True, "timeStep": "hourly", "operator": "less", "terms": [], "comments": "New API"}
-        res = client.post(
-            f"/v1/studies/{study_id}/bindingconstraints",
-            json={"name": bc_id_wo_group, **args},
-            headers=admin_headers,
-        )
+        res = client.post(f"/v1/studies/{study_id}/bindingconstraints", json={"name": bc_id_wo_group, **args})
         assert res.status_code in {200, 201}
         assert res.json()["group"] == "default"
 
@@ -731,7 +600,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.post(
             f"/v1/studies/{study_id}/bindingconstraints",
             json={"name": bc_id_w_group, "group": "specific_grp", **args},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}
         assert res.json()["group"] == "specific_grp"
@@ -742,12 +610,11 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.post(
             f"/v1/studies/{study_id}/bindingconstraints",
             json={"name": bc_id_w_matrix, "less_term_matrix": matrix_lt3.tolist(), **args},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
         if study_type == "variant":
-            res = client.get(f"/v1/studies/{study_id}/commands", headers=admin_headers)
+            res = client.get(f"/v1/studies/{study_id}/commands")
             last_cmd_args = res.json()[-1]["args"]
             less_term_matrix = last_cmd_args["less_term_matrix"]
             equal_term_matrix = last_cmd_args["equal_term_matrix"]
@@ -756,10 +623,10 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
 
         # Check that raw matrices are created
         for term in ["lt", "gt", "eq"]:
+            path = f"input/bindingconstraints/{bc_id_w_matrix}_{term}"
             res = client.get(
                 f"/v1/studies/{study_id}/raw",
-                params={"path": f"input/bindingconstraints/{bc_id_w_matrix}_{term}", "depth": 1, "formatted": True},  # type: ignore
-                headers=admin_headers,
+                params={"path": path, "depth": 1, "formatted": True},  # type: ignore
             )
             assert res.status_code == 200, res.json()
             data = res.json()["data"]
@@ -779,7 +646,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 {"weight": 1, "offset": 2, "data": {"area1": area1_id, "area2": area2_id}},
                 {"weight": 1, "offset": 2, "data": {"area": area1_id, "cluster": cluster_id}},
             ],
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
 
@@ -787,7 +653,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.post(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}/terms",
             json=[{"weight": 1, "offset": 2}],
-            headers=admin_headers,
         )
         assert res.status_code == 422, res.json()
         exception = res.json()["exception"]
@@ -800,7 +665,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.post(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}/terms",
             json=[{"weight": 99, "offset": 0, "data": {"area1": area1_id, "area2": area2_id}}],
-            headers=admin_headers,
         )
         assert res.status_code == 409, res.json()
         exception = res.json()["exception"]
@@ -810,10 +674,7 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         assert f"{area1_id}%{area2_id}" in description, "Error message should contain the duplicate term ID"
 
         # Get binding constraints list to check added terms
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}",
-            headers=admin_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -837,22 +698,22 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}/terms",
             json=[
-                {"id": f"{area1_id}%{area2_id}", "weight": 4.4, "offset": 1},
+                {
+                    "id": f"{area1_id}%{area2_id}",
+                    "weight": 4.4,
+                    "offset": 1,
+                },
                 {
                     "id": f"{area1_id}.{cluster_id}",
                     "weight": 5.1,
                     "data": {"area": area1_id, "cluster": cluster_id},
                 },
             ],
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
 
         # Asserts terms were updated
-        res = client.get(
-            f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}",
-            headers=admin_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}")
         assert res.status_code == 200, res.json()
         binding_constraint = res.json()
         constraint_terms = binding_constraint["terms"]
@@ -881,7 +742,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_matrix}",
             json={"group": grp_name},
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
         assert res.json()["group"] == grp_name
@@ -890,14 +750,12 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_matrix}",
             json={"greater_term_matrix": matrix_lt3.tolist()},
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
 
         res = client.get(
             f"/v1/studies/{study_id}/raw",
             params={"path": f"input/bindingconstraints/{bc_id_w_matrix}_gt"},
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
         assert res.json()["data"] == matrix_lt3.tolist()
@@ -907,13 +765,12 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_matrix}",
             json={"timeStep": "daily"},
-            headers=admin_headers,
         )
         assert res.status_code == 200, res.json()
 
         if study_type == "variant":
             # Check the last command is a change on `time_step` field only
-            res = client.get(f"/v1/studies/{study_id}/commands", headers=admin_headers)
+            res = client.get(f"/v1/studies/{study_id}/commands")
             commands = res.json()
             command_args = commands[-1]["args"]
             assert command_args["time_step"] == "daily"
@@ -935,7 +792,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                     "depth": 1,
                     "formatted": True,
                 },  # type: ignore
-                headers=admin_headers,
             )
             assert res.status_code == 200, res.json()
             assert res.json()["data"] == expected_matrix.tolist()
@@ -945,11 +801,11 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         # =============================
 
         # Delete a binding constraint
-        res = client.delete(f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}", headers=admin_headers)
+        res = client.delete(f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_group}")
         assert res.status_code == 200, res.json()
 
         # Asserts that the deletion worked
-        res = client.get(f"/v1/studies/{study_id}/bindingconstraints", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/bindingconstraints")
         assert len(res.json()) == 2
 
         # =============================
@@ -968,7 +824,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 "comments": "New API",
                 "values": [[]],
             },
-            headers=admin_headers,
         )
         assert res.status_code == 422, res.json()
         assert res.json()["description"] == "You cannot fill 'values' as it refers to the matrix before v8.7"
@@ -977,7 +832,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{bc_id_w_matrix}",
             json={"values": [[]]},
-            headers=admin_headers,
         )
         assert res.status_code == 422, res.json()
         assert res.json()["exception"] == "InvalidFieldForVersionError"
@@ -995,7 +849,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 "greater_term_matrix": matrix_gt2.tolist(),
                 **args,
             },
-            headers=admin_headers,
         )
         assert res.status_code == 422, res.json()
         exception = res.json()["exception"]
@@ -1020,7 +873,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 "group": "Group 1",
                 **args,
             },
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
         first_bc_id = res.json()["id"]
@@ -1029,17 +881,13 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         random_matrix = pd.DataFrame(generator.integers(0, 10, size=(4, 1)))
         _upload_matrix(
             client,
-            admin_access_token,
             study_id,
             f"input/bindingconstraints/{first_bc_id}_gt",
             random_matrix,
         )
 
         # Validation should fail
-        res = client.get(
-            f"/v1/studies/{study_id}/constraint-groups/Group 1/validate",
-            headers=admin_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate")
         assert res.status_code == 422
         obj = res.json()
         assert obj["exception"] == "WrongMatrixHeightError"
@@ -1049,7 +897,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{first_bc_id}",
             json={"greater_term_matrix": matrix_lt3.tolist()},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
@@ -1059,10 +906,7 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         #
 
         # Asserts everything is ok.
-        res = client.get(
-            f"/v1/studies/{study_id}/constraint-groups/Group 1/validate",
-            headers=admin_headers,
-        )
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate")
         assert res.status_code == 200, res.json()
 
         matrix_gt4 = np.ones((8784, 4))  # Wrong number of columns
@@ -1074,13 +918,12 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 "group": "group 1",  # Same group, but different case
                 **args,
             },
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
         second_bc_id = res.json()["id"]
 
         # validate the BC group "Group 1"
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate")
         assert res.status_code == 422, res.json()
         assert res.json()["exception"] == "MatrixWidthMismatchError"
         description = res.json()["description"]
@@ -1091,7 +934,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{second_bc_id}",
             json={"greater_term_matrix": matrix_lt3.tolist()},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
@@ -1111,7 +953,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
                 "group": "Group 2",
                 **args,
             },
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
         third_bd_id = res.json()["id"]
@@ -1119,13 +960,12 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"v1/studies/{study_id}/bindingconstraints/{third_bd_id}",
             json={"group": "Group 1"},
-            headers=admin_headers,
         )
         # This should succeed but cause the validation endpoint to fail.
         assert res.status_code in {200, 201}, res.json()
 
         # validate the BC group "Group 1"
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 1/validate")
         assert res.status_code == 422, res.json()
         assert res.json()["exception"] == "MatrixWidthMismatchError"
         description = res.json()["description"]
@@ -1136,7 +976,6 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"/v1/studies/{study_id}/bindingconstraints/{third_bd_id}",
             json={"greater_term_matrix": matrix_lt3.tolist()},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
@@ -1149,24 +988,22 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         res = client.put(
             f"v1/studies/{study_id}/bindingconstraints/{second_bc_id}",
             json={"group": "Group 2"},
-            headers=admin_headers,
         )
         assert res.status_code in {200, 201}, res.json()
 
         # validate the "Group 2": for the moment the BC is valid
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 2/validate", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/Group 2/validate")
         assert res.status_code in {200, 201}, res.json()
 
         res = client.put(
             f"v1/studies/{study_id}/bindingconstraints/{second_bc_id}",
             json={"greater_term_matrix": matrix_gt4.tolist()},
-            headers=admin_headers,
         )
         # This should succeed but cause the validation endpoint to fail.
         assert res.status_code in {200, 201}, res.json()
 
         # Collect all the binding constraints groups
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups")
         assert res.status_code in {200, 201}, res.json()
         groups = res.json()
         assert set(groups) == {"default", "random_grp", "Group 1", "Group 2"}
@@ -1186,7 +1023,7 @@ def test_for_version_870(self, client: TestClient, admin_access_token: str, stud
         ]
 
         # Validate all binding constraints groups
-        res = client.get(f"/v1/studies/{study_id}/constraint-groups/validate-all", headers=admin_headers)
+        res = client.get(f"/v1/studies/{study_id}/constraint-groups/validate-all")
         assert res.status_code == 422, res.json()
         exception = res.json()["exception"]
         description = res.json()["description"]
diff --git a/tests/storage/repository/filesystem/matrix/input_series_matrix_test.py b/tests/storage/repository/filesystem/matrix/input_series_matrix_test.py
deleted file mode 100644
index a422c43f8d..0000000000
--- a/tests/storage/repository/filesystem/matrix/input_series_matrix_test.py
+++ /dev/null
@@ -1,42 +0,0 @@
-from pathlib import Path
-from unittest.mock import Mock
-
-from antarest.study.storage.rawstudy.model.filesystem.config.model import FileStudyTreeConfig
-from antarest.study.storage.rawstudy.model.filesystem.matrix.input_series_matrix import InputSeriesMatrix
-
-
-def test_get(tmp_path: Path) -> None:
-    file = tmp_path / "input.txt"
-    content = """
-100000	100000	0.010000	0.010000	0	0	0	0
-100000	100000	0.010000	0.010000	0	0	0	0
-    """
-    file.write_text(content)
-
-    config = FileStudyTreeConfig(study_path=file, path=file, version=-1, study_id="id")
-    node = InputSeriesMatrix(context=Mock(), config=config, nb_columns=8)
-
-    assert node.load() == {
-        "columns": [0, 1, 2, 3, 4, 5, 6, 7],
-        "data": [
-            [100000.0, 100000.0, 0.01, 0.01, 0.0, 0.0, 0.0, 0.0],
-            [100000.0, 100000.0, 0.01, 0.01, 0.0, 0.0, 0.0, 0.0],
-        ],
-        "index": [0, 1],
-    }
-
-
-def test_save(tmp_path: Path) -> None:
-    file = tmp_path / "input.txt"
-    file.write_text("\n")
-
-    config = FileStudyTreeConfig(study_path=file, path=file, study_id="id", version=-1)
-    node = InputSeriesMatrix(context=Mock(), config=config)
-
-    node.dump({"columns": [0, 1], "data": [[1, 2], [3, 4]], "index": [0, 1]})
-    assert (
-        file.read_text()
-        == """1\t2
-3\t4
-"""
-    )
diff --git a/tests/storage/repository/filesystem/matrix/output_series_matrix_test.py b/tests/storage/repository/filesystem/matrix/output_series_matrix_test.py
deleted file mode 100644
index d739e73b0d..0000000000
--- a/tests/storage/repository/filesystem/matrix/output_series_matrix_test.py
+++ /dev/null
@@ -1,91 +0,0 @@
-from pathlib import Path
-from unittest.mock import Mock
-
-import pandas as pd
-
-from antarest.study.storage.rawstudy.model.filesystem.config.model import FileStudyTreeConfig
-from antarest.study.storage.rawstudy.model.filesystem.matrix.head_writer import AreaHeadWriter
-from antarest.study.storage.rawstudy.model.filesystem.matrix.matrix import MatrixFrequency
-from antarest.study.storage.rawstudy.model.filesystem.matrix.output_series_matrix import OutputSeriesMatrix
-
-MATRIX_DAILY_DATA = """\
-DE\tarea\tva\thourly
-\tVARIABLES\tBEGIN\tEND
-\t2\t1\t2
-
-DE\thourly\t\t\t\t01_solar\t02_wind_on
-\t\t\t\t\tMWh\tMWh
-\tindex\tday\tmonth\thourly\tEXP\tEXP
-\t1\t1\tJAN\t00:00\t27000\t600
-\t2\t1\tJAN\t01:00\t48000\t34400
-"""
-
-
-def test_get(tmp_path: Path) -> None:
-    file = tmp_path / "matrix-daily.txt"
-    file.write_text("\n\n\n\nmock\tfile\ndummy\tdummy\ndummy\tdummy\ndummy\tdummy")
-    config = FileStudyTreeConfig(study_path=file, path=file, study_id="id", version=-1)
-
-    serializer = Mock()
-    serializer.extract_date.return_value = (
-        pd.Index(["01/02", "01/01"]),
-        pd.DataFrame(
-            data={
-                ("01_solar", "MWh", "EXP"): [27000, 48000],
-                ("02_wind_on", "MWh", "EXP"): [600, 34400],
-            }
-        ),
-    )
-
-    matrix = pd.DataFrame(
-        data={
-            ("01_solar", "MWh", "EXP"): [27000, 48000],
-            ("02_wind_on", "MWh", "EXP"): [600, 34400],
-        },
-        index=["01/02", "01/01"],
-    )
-
-    node = OutputSeriesMatrix(
-        context=Mock(),
-        config=config,
-        freq=MatrixFrequency.DAILY,
-        date_serializer=serializer,
-        head_writer=AreaHeadWriter(area="", data_type="", freq=""),
-    )
-    assert node.load() == matrix.to_dict(orient="split")
-
-
-def test_save(tmp_path: Path) -> None:
-    file = tmp_path / "matrix-daily.txt"
-    config = FileStudyTreeConfig(study_path=file, path=file, study_id="id", version=-1)
-
-    serializer = Mock()
-    serializer.build_date.return_value = pd.DataFrame(
-        {
-            0: ["DE", "", "", "", ""],
-            1: ["hourly", "", "index", 1, 2],
-            2: ["", "", "day", "1", "1"],
-            3: ["", "", "month", "JAN", "JAN"],
-            4: ["", "", "hourly", "00:00", "01:00"],
-        }
-    )
-
-    node = OutputSeriesMatrix(
-        context=Mock(),
-        config=config,
-        freq=MatrixFrequency.DAILY,
-        date_serializer=serializer,
-        head_writer=AreaHeadWriter(area="de", data_type="va", freq="hourly"),
-    )
-
-    matrix = pd.DataFrame(
-        data={
-            ("01_solar", "MWh", "EXP"): [27000, 48000],
-            ("02_wind_on", "MWh", "EXP"): [600, 34400],
-        },
-        index=["01/01", "01/02"],
-    )
-
-    node.dump(matrix.to_dict(orient="split"))
-    actual = file.read_text()
-    assert actual == MATRIX_DAILY_DATA
diff --git a/tests/storage/repository/filesystem/matrix/date_serializer_test.py b/tests/storage/repository/filesystem/matrix/test_date_serializer.py
similarity index 100%
rename from tests/storage/repository/filesystem/matrix/date_serializer_test.py
rename to tests/storage/repository/filesystem/matrix/test_date_serializer.py
diff --git a/tests/storage/repository/filesystem/matrix/head_writer_test.py b/tests/storage/repository/filesystem/matrix/test_head_writer.py
similarity index 100%
rename from tests/storage/repository/filesystem/matrix/head_writer_test.py
rename to tests/storage/repository/filesystem/matrix/test_head_writer.py
diff --git a/tests/storage/repository/filesystem/matrix/test_input_series_matrix.py b/tests/storage/repository/filesystem/matrix/test_input_series_matrix.py
new file mode 100644
index 0000000000..6b7bcbaa01
--- /dev/null
+++ b/tests/storage/repository/filesystem/matrix/test_input_series_matrix.py
@@ -0,0 +1,94 @@
+import textwrap
+import typing as t
+from pathlib import Path
+from unittest.mock import Mock
+
+import pytest
+
+from antarest.matrixstore.service import ISimpleMatrixService
+from antarest.matrixstore.uri_resolver_service import UriResolverService
+from antarest.study.storage.rawstudy.model.filesystem.config.model import FileStudyTreeConfig
+from antarest.study.storage.rawstudy.model.filesystem.context import ContextServer
+from antarest.study.storage.rawstudy.model.filesystem.folder_node import ChildNotFoundError
+from antarest.study.storage.rawstudy.model.filesystem.matrix.input_series_matrix import InputSeriesMatrix
+
+
+class TestInputSeriesMatrix:
+    @pytest.fixture(name="my_study_config")
+    def fixture_my_study_config(self, tmp_path: Path) -> FileStudyTreeConfig:
+        """
+        Construct a FileStudyTreeConfig object for a dummy study stored in a temporary directory.
+        """
+        return FileStudyTreeConfig(
+            study_path=tmp_path,
+            path=tmp_path / "input.txt",
+            study_id="df0a8aa9-6c6f-4e8b-a84e-45de2fb29cd3",
+            version=800,
+        )
+
+    def test_load(self, my_study_config: FileStudyTreeConfig) -> None:
+        file = my_study_config.path
+        content = textwrap.dedent(
+            """\
+            100000\t100000\t0.010000\t0.010000\t0\t0\t0\t3.14
+            100000\t100000\t0.010000\t0.010000\t0\t0\t0\t6.28
+            """
+        )
+        file.write_text(content)
+
+        node = InputSeriesMatrix(context=Mock(), config=my_study_config, nb_columns=8)
+        actual = node.load()
+        expected = {
+            "columns": [0, 1, 2, 3, 4, 5, 6, 7],
+            "data": [
+                [100000.0, 100000.0, 0.01, 0.01, 0.0, 0.0, 0.0, 3.14],
+                [100000.0, 100000.0, 0.01, 0.01, 0.0, 0.0, 0.0, 6.28],
+            ],
+            "index": [0, 1],
+        }
+        assert actual == expected
+
+    def test_load__file_not_found(self, my_study_config: FileStudyTreeConfig) -> None:
+        node = InputSeriesMatrix(context=Mock(), config=my_study_config)
+        with pytest.raises(ChildNotFoundError) as ctx:
+            node.load()
+        err_msg = str(ctx.value)
+        assert "input.txt" in err_msg
+        assert my_study_config.study_id in err_msg
+        assert "not found" in err_msg.lower()
+
+    def test_load__link_to_matrix(self, my_study_config: FileStudyTreeConfig) -> None:
+        link = my_study_config.path.with_suffix(".txt.link")
+        matrix_uri = "matrix://54e252eb14c0440055c82520c338376ff436e1d7ed6cb7283084c89e2e472c42"
+        matrix_obj = {
+            "data": [[1, 2], [3, 4]],
+            "index": [0, 1],
+            "columns": [0, 1],
+        }
+        link.write_text(matrix_uri)
+
+        def resolve(uri: str, formatted: bool = True) -> t.Dict[str, t.Any]:
+            assert uri == matrix_uri
+            assert formatted is True
+            return matrix_obj
+
+        context = ContextServer(
+            matrix=Mock(spec=ISimpleMatrixService),
+            resolver=Mock(spec=UriResolverService, resolve=resolve),
+        )
+
+        node = InputSeriesMatrix(context=context, config=my_study_config)
+        actual = node.load()
+        assert actual == matrix_obj
+
+    def test_save(self, my_study_config: FileStudyTreeConfig) -> None:
+        node = InputSeriesMatrix(context=Mock(), config=my_study_config)
+        node.dump({"columns": [0, 1], "data": [[1, 2], [3, 4]], "index": [0, 1]})
+        actual = my_study_config.path.read_text()
+        expected = textwrap.dedent(
+            """\
+            1\t2
+            3\t4
+            """
+        )
+        assert actual == expected
diff --git a/tests/storage/repository/filesystem/matrix/test_output_series_matrix.py b/tests/storage/repository/filesystem/matrix/test_output_series_matrix.py
new file mode 100644
index 0000000000..c93f999627
--- /dev/null
+++ b/tests/storage/repository/filesystem/matrix/test_output_series_matrix.py
@@ -0,0 +1,116 @@
+from pathlib import Path
+from unittest.mock import Mock
+
+import pandas as pd
+import pytest
+
+from antarest.study.storage.rawstudy.model.filesystem.config.model import FileStudyTreeConfig
+from antarest.study.storage.rawstudy.model.filesystem.folder_node import ChildNotFoundError
+from antarest.study.storage.rawstudy.model.filesystem.matrix.head_writer import AreaHeadWriter
+from antarest.study.storage.rawstudy.model.filesystem.matrix.matrix import MatrixFrequency
+from antarest.study.storage.rawstudy.model.filesystem.matrix.output_series_matrix import OutputSeriesMatrix
+
+MATRIX_DAILY_DATA = """\
+DE\tarea\tva\thourly
+\tVARIABLES\tBEGIN\tEND
+\t2\t1\t2
+
+DE\thourly\t\t\t\t01_solar\t02_wind_on
+\t\t\t\t\tMWh\tMWh
+\tindex\tday\tmonth\thourly\tEXP\tEXP
+\t1\t1\tJAN\t00:00\t27000\t600
+\t2\t1\tJAN\t01:00\t48000\t34400
+"""
+
+
+class TestOutputSeriesMatrix:
+    @pytest.fixture(name="my_study_config")
+    def fixture_my_study_config(self, tmp_path: Path) -> FileStudyTreeConfig:
+        """
+        Construct a FileStudyTreeConfig object for a dummy study stored in a temporary directory.
+        """
+        return FileStudyTreeConfig(
+            study_path=tmp_path,
+            path=tmp_path / "matrix-daily.txt",
+            study_id="df0a8aa9-6c6f-4e8b-a84e-45de2fb29cd3",
+            version=800,
+        )
+
+    def test_load(self, my_study_config: FileStudyTreeConfig) -> None:
+        file = my_study_config.path
+        file.write_text("\n\n\n\nmock\tfile\ndummy\tdummy\ndummy\tdummy\ndummy\tdummy")
+
+        serializer = Mock()
+        serializer.extract_date.return_value = (
+            pd.Index(["01/02", "01/01"]),
+            pd.DataFrame(
+                data={
+                    ("01_solar", "MWh", "EXP"): [27000, 48000],
+                    ("02_wind_on", "MWh", "EXP"): [600, 34400],
+                }
+            ),
+        )
+
+        matrix = pd.DataFrame(
+            data={
+                ("01_solar", "MWh", "EXP"): [27000, 48000],
+                ("02_wind_on", "MWh", "EXP"): [600, 34400],
+            },
+            index=["01/02", "01/01"],
+        )
+
+        node = OutputSeriesMatrix(
+            context=Mock(),
+            config=my_study_config,
+            freq=MatrixFrequency.DAILY,
+            date_serializer=serializer,
+            head_writer=AreaHeadWriter(area="", data_type="", freq=""),
+        )
+        assert node.load() == matrix.to_dict(orient="split")
+
+    def test_load__file_not_found(self, my_study_config: FileStudyTreeConfig) -> None:
+        node = OutputSeriesMatrix(
+            context=Mock(),
+            config=my_study_config,
+            freq=MatrixFrequency.DAILY,
+            date_serializer=Mock(),
+            head_writer=AreaHeadWriter(area="", data_type="", freq=""),
+        )
+        with pytest.raises(ChildNotFoundError) as ctx:
+            node.load()
+        err_msg = str(ctx.value)
+        assert "'matrix-daily.txt" in err_msg
+        assert my_study_config.study_id in err_msg
+        assert "not found" in err_msg.lower()
+
+    def test_save(self, my_study_config: FileStudyTreeConfig) -> None:
+        serializer = Mock()
+        serializer.build_date.return_value = pd.DataFrame(
+            {
+                0: ["DE", "", "", "", ""],
+                1: ["hourly", "", "index", 1, 2],
+                2: ["", "", "day", "1", "1"],
+                3: ["", "", "month", "JAN", "JAN"],
+                4: ["", "", "hourly", "00:00", "01:00"],
+            }
+        )
+
+        node = OutputSeriesMatrix(
+            context=Mock(),
+            config=my_study_config,
+            freq=MatrixFrequency.DAILY,
+            date_serializer=serializer,
+            head_writer=AreaHeadWriter(area="de", data_type="va", freq="hourly"),
+        )
+
+        matrix = pd.DataFrame(
+            data={
+                ("01_solar", "MWh", "EXP"): [27000, 48000],
+                ("02_wind_on", "MWh", "EXP"): [600, 34400],
+            },
+            index=["01/01", "01/02"],
+        )
+
+        node.dump(matrix.to_dict(orient="split"))  # type: ignore
+        actual = my_study_config.path.read_text()
+        assert actual == MATRIX_DAILY_DATA