Merge pull request #30 from raisadz/increase-coverage

Modify pandas-like merge to have the same behaviour as in Polars

narwhals/pandas_like/dataframe.py

@@ -177,18 +177,13 @@ def join(
         if isinstance(right_on, str):
             right_on = [right_on]
 
-        if overlap := (set(self.columns) - set(left_on)).intersection(
-            set(other.columns) - set(right_on),
-        ):
-            msg = f"Found overlapping columns in join: {overlap}. Please rename columns to avoid this."
-            raise ValueError(msg)
-
         return self._from_dataframe(
             self._dataframe.merge(
                 other._dataframe,
                 left_on=left_on,
                 right_on=right_on,
                 how=how,
+                suffixes=("", "_right"),
             ),
         )
 

tests/test_common.py

@@ -173,7 +173,7 @@ def test_rename(df_raw: Any) -> None:
 @pytest.mark.parametrize("df_raw", [df_pandas, df_lazy])
 def test_join(df_raw: Any) -> None:
     df = nw.LazyFrame(df_raw)
-    df_right = df.rename({"z": "z_right"})
+    df_right = df
     result = df.join(df_right, left_on=["a", "b"], right_on=["a", "b"], how="inner")
     result_native = nw.to_native(result)
     expected = {"a": [1, 3, 2], "b": [4, 4, 6], "z": [7.0, 8, 9], "z_right": [7.0, 8, 9]}