fix tests

Author: TrevorBergeron

bigframes/operations/datetimes.py

@@ -23,7 +23,6 @@
 
 from bigframes import dataframe, dtypes, series
 from bigframes.core import log_adapter
-from bigframes.core.reshape import concat
 import bigframes.operations as ops
 import bigframes.operations.base
 
@@ -79,13 +78,12 @@ def month(self) -> series.Series:
         return self._apply_unary_op(ops.month_op)
 
     def isocalendar(self) -> dataframe.DataFrame:
-        years = self._apply_unary_op(ops.iso_year_op)
-        weeks = self._apply_unary_op(ops.iso_week_op)
-        days = self._apply_unary_op(ops.iso_day_op)
-
-        result = concat.concat([years, weeks, days], axis=1)
-        result.columns = pandas.Index(["year", "week", "day"])
-        return result
+        iso_ops = [ops.iso_year_op, ops.iso_week_op, ops.iso_day_op]
+        labels = pandas.Index(["year", "week", "day"])
+        block = self._block.project_exprs(
+            [op.as_expr(self._value_column) for op in iso_ops], labels, drop=True
+        )
+        return dataframe.DataFrame(block)
 
     # Time accessors
     @property

tests/system/small/operations/test_dates.py

@@ -76,8 +76,11 @@ def test_date_series_diff_agg(scalars_dfs):
 def test_date_can_cast_after_accessor(scalars_dfs):
     bf_df, pd_df = scalars_dfs
 
-    actual_result = bf_df.date_col.dt.isocalendar().week.astype("Int64").to_pandas()
-    expected_result = pd_df.date_col.dt.isocalendar().week.astype("Int64")
+    actual_result = bf_df["date_col"].dt.isocalendar().week.astype("Int64").to_pandas()
+    # convert to pd date type rather than arrow, as pandas doesn't handle arrow date well here
+    expected_result = (
+        pd.to_datetime(pd_df["date_col"]).dt.isocalendar().week.astype("Int64")
+    )
 
     pandas.testing.assert_series_equal(
         actual_result, expected_result, check_dtype=False, check_index_type=False

tests/system/small/operations/test_datetimes.py

@@ -603,14 +603,3 @@ def test_to_datetime(scalars_dfs, col):
     testing.assert_series_equal(
         actual_result, expected_result, check_dtype=False, check_index_type=False
     )
-
-
-def test_timedelta_can_cast_after_dt_accessor(timedelta_series):
-    bf_s, pd_s = timedelta_series
-
-    actual_result = bf_s.dt.isocalendar().week.astype("Int64").to_pandas()
-    expected_result = pd_s.dt.isocalendar().week.astype("Int64")
-
-    assert_series_equal(
-        actual_result, expected_result, check_dtype=False, check_index_type=False
-    )