Add settlement period option to dersysdata

pyelexon/pyelexon.py

@@ -71,13 +71,19 @@ def get_detsysprices(self, settlement_date: date, settlement_period: int) -> byt
         self._missing_data(r, xpath="./responseBody/responseList/item/[id]")
         return r.content
 
-    def get_dersysdata(self, settlement_date: date) -> bytes:
+    def get_dersysdata(self, settlement_date: date,
+                       settlement_period: Optional[int] = None) -> bytes:
         """Method for fetching DERSYSDATA data for the specified settlement period"""
         report = "DERSYSDATA"
+
         params = {
             "from_settlement_date": self._date_fmt(settlement_date),
             "to_settlement_date": self._date_fmt(settlement_date),
         }
+
+        if settlement_period is not None:
+            params["settlement_period"] = settlement_period
+
         r = self._fetch_from_elexon(report, params)
         self._missing_data(r, xpath="./responseBody/responseList/item/[recordType]")
         return r.content

tests/test_pyelexon.py

@@ -55,6 +55,13 @@ def test_get_dersysdata(client):
     assert isinstance(r, bytes)
 
 
+@pytest.mark.vcr
+def test_get_dersysdata_with_settlement_period(client):
+    r = client.get_dersysdata(settlement_date=date(2021, 1, 1),
+                              settlement_period=1)
+    assert isinstance(r, bytes)
+
+
 @pytest.mark.vcr
 def test_get_lolpdrm(client):
     r = client.get_lolpdrm(settlement_date=date(2021, 1, 1))