test(pyflink): adjust common tests for dir outputs

ibis/backends/tests/test_export.py

@@ -222,9 +222,10 @@ def test_table_to_parquet_writer_kwargs(version, tmp_path, backend, awards_playe
         awards_players.to_pandas().fillna(pd.NA), df.fillna(pd.NA)
     )
 
-    md = pa.parquet.read_metadata(outparquet)
+    if outparquet.is_file():
+        md = pa.parquet.read_metadata(outparquet)
 
-    assert md.format_version == version
+        assert md.format_version == version
 
 
 @pytest.mark.notimpl(
@@ -290,9 +291,10 @@ def test_memtable_to_file(tmp_path, con, ftype, monkeypatch):
 
     getattr(con, f"to_{ftype}")(memtable, outfile)
 
-    assert outfile.is_file()
+    assert outfile.exists()
 
 
+@pytest.mark.never(["pyspark"], reason="backend writes a dir", raises=IsADirectoryError)
 def test_table_to_csv(tmp_path, backend, awards_players):
     outcsv = tmp_path / "out.csv"
 
@@ -311,6 +313,7 @@ def test_table_to_csv(tmp_path, backend, awards_players):
     reason="cannot inline WriteOptions objects",
     raises=DuckDBParserException,
 )
+@pytest.mark.never(["pyspark"], reason="backend writes a dir", raises=IsADirectoryError)
 @pytest.mark.parametrize("delimiter", [";", "\t"], ids=["semicolon", "tab"])
 def test_table_to_csv_writer_kwargs(delimiter, tmp_path, awards_players):
     outcsv = tmp_path / "out.csv"