Add test file for data management.

Author: Lenr4

tests/data_management/test_clean_apple.py

@@ -0,0 +1,78 @@
+import numpy as np
+import pandas as pd
+import pytest
+
+from lennart_epp.data_management.clean_apple import (
+    _convert_to_datetime,
+    _convert_to_numeric,
+    _handle_missing_values,
+    _remove_duplicates,
+    _select_and_rename_column,
+    _validate_dataframe,
+)
+
+
+@pytest.fixture
+def raw_data():
+    data = {
+        "Date": [
+            "2022-01-01",
+            "2022-01-02",
+            "2022-01-03",
+            "2022-01-03",
+            "2022-01-04",
+        ],
+        "Close": [100, np.nan, 102, 102, 105],
+        "Other": ["A", "B", "C", "C", "D"],
+    }
+    return pd.DataFrame(data)
+
+
+def test_select_and_rename_column(raw_data):
+    result = _select_and_rename_column(raw_data)
+    assert list(result.columns) == ["close_price"]
+    pd.testing.assert_series_equal(
+        result["close_price"], raw_data["Close"], check_names=False
+    )
+
+
+expected_value_missing = 100
+
+
+def test_handle_missing_values(raw_data):
+    result = _handle_missing_values(raw_data)
+    assert result.isna().sum().sum() == 0
+    assert result.loc[1, "Close"] == expected_value_missing
+
+
+expected_length_index = 4
+
+
+def test_remove_duplicates(raw_data):
+    df = raw_data.copy().set_index("Date")
+    result = _remove_duplicates(df)
+    assert result.index.duplicated().sum() == 0
+    assert len(result) == expected_length_index
+
+
+def test_convert_to_numeric(raw_data):
+    df = raw_data.copy().astype(str)
+    result = _convert_to_numeric(df)
+    for col in result.columns:
+        assert result[col].dtype == "float32"
+    np.testing.assert_almost_equal(result.loc[0, "Close"], 100.0, decimal=2)
+
+
+def test_validate_dataframe(raw_data):
+    _validate_dataframe(raw_data)
+    df_missing = raw_data.drop(columns=["Close"])
+    with pytest.raises(
+        ValueError, match="The DataFrame does not contain a 'Close' column."
+    ):
+        _validate_dataframe(df_missing)
+
+
+def test_convert_to_datetime(raw_data):
+    result = _convert_to_datetime(raw_data.copy())
+    assert isinstance(result.index, pd.DatetimeIndex)
+    assert result.index[0] == pd.Timestamp("2022-01-01")