BUG: Use suffixes in sjoin's how==right branch (#2065)

* Use suffixes in how==right

* add tests

* slightly nicer formatting

* slightly nicer formatting

* add ,

* Update test_sjoin.py

* Update test_sjoin.py

Co-authored-by: Martin Fleischmann <martin@martinfleischmann.net>

geopandas/tools/sjoin.py

@@ -319,6 +319,7 @@ def _frame_join(indices, left_df, right_df, how, lsuffix, rsuffix):
                 left_index=True,
                 right_on="_key_left",
                 how="right",
+                suffixes=("_{}".format(lsuffix), "_{}".format(rsuffix)),
             )
             .set_index(index_right)
             .drop(["_key_left", "_key_right"], axis=1)

geopandas/tools/tests/test_sjoin.py

@@ -89,6 +89,23 @@ def dfs(request):
 
 
 class TestSpatialJoin:
+    @pytest.mark.parametrize(
+        "how, lsuffix, rsuffix, expected_cols",
+        [
+            ("left", "left", "right", {"col_left", "col_right", "index_right"}),
+            ("inner", "left", "right", {"col_left", "col_right", "index_right"}),
+            ("right", "left", "right", {"col_left", "col_right", "index_left"}),
+            ("left", "lft", "rgt", {"col_lft", "col_rgt", "index_rgt"}),
+            ("inner", "lft", "rgt", {"col_lft", "col_rgt", "index_rgt"}),
+            ("right", "lft", "rgt", {"col_lft", "col_rgt", "index_lft"}),
+        ],
+    )
+    def test_suffixes(self, how: str, lsuffix: str, rsuffix: str, expected_cols):
+        left = GeoDataFrame({"col": [1], "geometry": [Point(0, 0)]})
+        right = GeoDataFrame({"col": [1], "geometry": [Point(0, 0)]})
+        joined = sjoin(left, right, how=how, lsuffix=lsuffix, rsuffix=rsuffix)
+        assert set(joined.columns) == expected_cols | set(("geometry",))
+
     @pytest.mark.parametrize("dfs", ["default-index", "string-index"], indirect=True)
     def test_crs_mismatch(self, dfs):
         index, df1, df2, expected = dfs