feat: DataFrame.join supports Series other (#1303)

bigframes/dataframe.py

@@ -3033,8 +3033,15 @@ def merge(
         return DataFrame(block)
 
     def join(
-        self, other: DataFrame, *, on: Optional[str] = None, how: str = "left"
+        self,
+        other: Union[DataFrame, bigframes.series.Series],
+        *,
+        on: Optional[str] = None,
+        how: str = "left",
     ) -> DataFrame:
+        if isinstance(other, bigframes.series.Series):
+            other = other.to_frame()
+
         left, right = self, other
 
         if not left.columns.intersection(right.columns).empty:

tests/system/small/test_dataframe.py

@@ -2554,6 +2554,27 @@ def test_join_param_on(scalars_dfs, how):
         assert_pandas_df_equal(bf_result, pd_result, ignore_order=True)
 
 
+@all_joins
+def test_df_join_series(scalars_dfs, how):
+    bf_df, pd_df = scalars_dfs
+
+    bf_df_a = bf_df[["string_col", "int64_col", "rowindex_2"]]
+    bf_df_a = bf_df_a.assign(rowindex_2=bf_df_a["rowindex_2"] + 2)
+    bf_series_b = bf_df["float64_col"]
+
+    if how == "cross":
+        with pytest.raises(ValueError):
+            bf_df_a.join(bf_series_b, on="rowindex_2", how=how)
+    else:
+        bf_result = bf_df_a.join(bf_series_b, on="rowindex_2", how=how).to_pandas()
+
+        pd_df_a = pd_df[["string_col", "int64_col", "rowindex_2"]]
+        pd_df_a = pd_df_a.assign(rowindex_2=pd_df_a["rowindex_2"] + 2)
+        pd_series_b = pd_df["float64_col"]
+        pd_result = pd_df_a.join(pd_series_b, on="rowindex_2", how=how)
+        assert_pandas_df_equal(bf_result, pd_result, ignore_order=True)
+
+
 @pytest.mark.parametrize(
     ("by", "ascending", "na_position"),
     [

third_party/bigframes_vendored/pandas/core/frame.py

@@ -4384,7 +4384,7 @@ def join(self, other, *, on: Optional[str] = None, how: str) -> DataFrame:
 
         Args:
             other:
-                DataFrame with an Index similar to the Index of this one.
+                DataFrame or Series with an Index similar to the Index of this one.
             on:
                 Column in the caller to join on the index in other, otherwise
                 joins index-on-index. Like an Excel VLOOKUP operation.