Replace "\n" with os.linesep

optuna/cli.py

@@ -193,7 +193,7 @@ def _dump_value(records: List[Dict[str, Any]], header: List[str]) -> str:
         for column_name in header:
             row.append(str(record.get(column_name, "")))
         values.append(" ".join(row))
-    return "\n".join(values)
+    return os.linesep.join(values)
 
 
 def _dump_table(records: List[Dict[str, Any]], header: List[str]) -> str:
@@ -223,11 +223,11 @@ def _dump_table(records: List[Dict[str, Any]], header: List[str]) -> str:
             rows_string[i] += " " + row[column].get_string(value_type, max_width) + " |"
 
     ret = ""
-    ret += separator + "\n"
-    ret += header_string + "\n"
-    ret += separator + "\n"
-    ret += "\n".join(rows_string) + "\n"
-    ret += separator + "\n"
+    ret += separator + os.linesep
+    ret += header_string + os.linesep
+    ret += separator + os.linesep
+    ret += os.linesep.join(rows_string) + os.linesep
+    ret += separator + os.linesep
 
     return ret
 

tests/test_cli.py

@@ -74,9 +74,9 @@ def _parse_output(output: str, output_format: str) -> Any:
     if output_format == "value":
         # Currently, _parse_output with output_format="value" is used only for
         # `study-names` command.
-        return [{"name": values} for values in output.split("\n")]
+        return [{"name": values} for values in output.split(os.linesep)]
     elif output_format == "table":
-        rows = output.split("\n")
+        rows = output.split(os.linesep)
         assert all(len(rows[0]) == len(row) for row in rows)
         # Check ruled lines.
         assert rows[0] == rows[2] == rows[-1]