From 44098560e17baa275b0934362cde5bf9c84b5d4b Mon Sep 17 00:00:00 2001
From: gyx09212214-prog <243787584+gyx09212214-prog@users.noreply.github.com>
Date: Thu, 11 Jun 2026 16:24:40 +0800
Subject: [PATCH] Add IborSingleCurve time day count regression test

---
 unit_tests/legacy/test_FinIborSingleCurve.py | 38 ++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/unit_tests/legacy/test_FinIborSingleCurve.py b/unit_tests/legacy/test_FinIborSingleCurve.py
index 6fb6345b3..3593d1954 100644
--- a/unit_tests/legacy/test_FinIborSingleCurve.py
+++ b/unit_tests/legacy/test_FinIborSingleCurve.py
@@ -13,6 +13,7 @@
 from financepy.utils.day_count import DayCountTypes
 from financepy.utils.date import Date
 from financepy.utils.calendar import Calendar, CalendarTypes
+from financepy.utils.helpers import times_from_dates
 
 ########################################################################################
 
@@ -400,3 +401,40 @@ def test_reprice_inputs_for_all_interp_choices(interp_type):
 
     # If no exception, we are good
     assert True
+
+
+def test_df_uses_ibor_single_curve_time_day_count():
+    """Regression test for inherited DiscountCurve.df date conversion."""
+
+    value_dt = Date(1, 1, 2024)
+    maturity_dt = Date(1, 1, 2025)
+    depo = IborDeposit(
+        value_dt,
+        maturity_dt,
+        0.05,
+        DayCountTypes.ACT_360,
+    )
+
+    curve = IborSingleCurve(
+        value_dt,
+        [depo],
+        [],
+        [],
+        InterpTypes.FLAT_FWD_RATES,
+        time_dc_type=DayCountTypes.ACT_360,
+    )
+
+    curve_df = curve.df(maturity_dt)
+    act_360_time = times_from_dates(
+        maturity_dt,
+        value_dt,
+        DayCountTypes.ACT_360,
+    )
+    act_365f_time = times_from_dates(
+        maturity_dt,
+        value_dt,
+        DayCountTypes.ACT_365F,
+    )
+
+    assert curve_df == pytest.approx(curve.df_t(act_360_time))
+    assert curve_df != pytest.approx(curve.df_t(act_365f_time))