add test config and basic tests for csv_parser

tests/services/test_csv_parser.py

@@ -0,0 +1,49 @@
+import pytest
+from app.core.exceptions import InvalidCSVException
+from app.utils.csv_parser import parse_and_validate_csv
+
+
+def test_parse_valid_csv():
+    valid_csv = (
+        "transaction_id,date,amount,category,description\n"
+        "TX1001,2026-06-25,120.50,Groceries,Weekly grocery shop\n"
+        "TX1002,06/26/2026,15.00,Coffee,Morning latte\n"
+    )
+    result = parse_and_validate_csv(valid_csv.encode("utf-8"))
+    assert len(result) == 2
+    assert result[0]["transaction_id"] == "TX1001"
+    assert result[0]["amount"] == 120.50
+    assert result[0]["date"] == "2026-06-25"
+    assert result[1]["transaction_id"] == "TX1002"
+    assert result[1]["amount"] == 15.00
+    assert result[1]["date"] == "2026-06-26"
+
+
+def test_parse_missing_headers():
+    invalid_csv = (
+        "transaction_id,amount,category,description\n"
+        "TX1001,120.50,Groceries,Weekly grocery shop\n"
+    )
+    with pytest.raises(InvalidCSVException) as exc_info:
+        parse_and_validate_csv(invalid_csv.encode("utf-8"))
+    assert "Missing required CSV columns" in str(exc_info.value)
+
+
+def test_parse_invalid_amount():
+    invalid_csv = (
+        "transaction_id,date,amount,category,description\n"
+        "TX1001,2026-06-25,abc,Groceries,Weekly grocery shop\n"
+    )
+    with pytest.raises(InvalidCSVException) as exc_info:
+        parse_and_validate_csv(invalid_csv.encode("utf-8"))
+    assert "Invalid amount" in str(exc_info.value)
+
+
+def test_parse_invalid_date():
+    invalid_csv = (
+        "transaction_id,date,amount,category,description\n"
+        "TX1001,invalid-date,120.50,Groceries,Weekly grocery shop\n"
+    )
+    with pytest.raises(InvalidCSVException) as exc_info:
+        parse_and_validate_csv(invalid_csv.encode("utf-8"))
+    assert "Invalid date format" in str(exc_info.value)