adding test cases

tests/analysis/test_forecast.py

@@ -0,0 +1,17 @@
+from delta_barth.analysis import forecast as fc
+
+
+def test_sales_per_customer_success(sales_data):
+    customer_id = 1133
+    err, res = fc.sales_per_customer(sales_data, customer_id)
+
+    assert err == 0
+    assert res is not None
+
+
+def test_sales_per_customer_too_few_data_points(sales_data):
+    customer_id = 1000
+    err, res = fc.sales_per_customer(sales_data, customer_id)
+
+    assert err == 1
+    assert res is None

tests/conftest.py

@@ -0,0 +1,38 @@
+from pathlib import Path
+from typing import Any
+
+import pandas as pd
+import pytest
+
+
+# TODO: maybe include in main package depending if needed in future
+def _cvt_str_float(value: str) -> float:
+    import locale
+
+    locale.setlocale(locale.LC_NUMERIC, "de_DE.UTF-8")
+    return locale.atof(value)
+
+
+def _cvt_str_ts(value: str) -> Any:
+    date = value.split("_")[0]
+
+    return pd.to_datetime(date, format="%Y%m%d", errors="coerce")
+
+
+@pytest.fixture(scope="session")
+def sales_data() -> pd.DataFrame:
+    pwd = Path.cwd()
+    assert "barth" in pwd.parent.name.lower(), "not in project root directory"
+    data_pth = pwd / "./tests/_test_data/swm_f_umsatz_fakt.csv"
+    assert data_pth.exists(), "file to sales data not found"
+    data = pd.read_csv(data_pth, sep="\t")
+    data["betrag"] = data["betrag"].apply(_cvt_str_float)
+    data["buchungs_datum"] = data["buchungs_datum"].apply(_cvt_str_ts)
+    data = data.dropna(
+        how="any",
+        subset=["firma_refid", "beleg_typ", "buchungs_datum", "betrag"],
+        ignore_index=True,
+    )
+    data["buchungs_datum"] = pd.to_datetime(data["buchungs_datum"])
+
+    return data