removes tests for removed method

Author: spjuhel

climada/entity/measures/test/test_cost_income.py

@@ -134,29 +134,6 @@ def test_from_yaml(self, tmp_path):
         assert ci.periodic_income == 300.0
 
 
-# ---------------------------------------------------------------------------
-# _freq_to_days
-# ---------------------------------------------------------------------------
-
-
-class TestFreqToDays:
-    def test_yearly(self):
-        result = CostIncome._freq_to_days("Y")
-        assert result == "365d"
-
-    def test_monthly(self):
-        result = CostIncome._freq_to_days("M")
-        assert result == "30d"
-
-    def test_daily(self):
-        result = CostIncome._freq_to_days("D")
-        assert result == "1d"
-
-    def test_invalid(self):
-        with pytest.raises(ValueError):
-            CostIncome._freq_to_days("INVALID_FREQ_XYZ")
-
-
 # ---------------------------------------------------------------------------
 # _get_width_days
 # ---------------------------------------------------------------------------