fix: Presto _show_columns return type (apache#20757)

(cherry picked from commit 8c0ac90)

superset/db_engine_specs/presto.py

@@ -442,8 +442,7 @@ def _show_columns(
         full_table = quote(table_name)
         if schema:
             full_table = "{}.{}".format(quote(schema), full_table)
-        columns = inspector.bind.execute("SHOW COLUMNS FROM {}".format(full_table))
-        return columns
+        return inspector.bind.execute(f"SHOW COLUMNS FROM {full_table}").fetchall()
 
     column_type_mappings = (
         (

tests/integration_tests/db_engine_specs/presto_tests.py

@@ -89,7 +89,7 @@ def verify_presto_column(self, column, expected_results):
             "Null": (None, None, 2),
         }
         row = RowProxy(mock.Mock(), column, [None, None, None, None], keymap)
-        inspector.bind.execute = mock.Mock(return_value=[row])
+        inspector.bind.execute.return_value.fetchall = mock.Mock(return_value=[row])
         results = PrestoEngineSpec.get_columns(inspector, "", "")
         self.assertEqual(len(expected_results), len(results))
         for expected_result, result in zip(expected_results, results):
@@ -749,25 +749,29 @@ def test_show_columns(self):
         inspector.engine.dialect.identifier_preparer.quote_identifier = (
             lambda x: f'"{x}"'
         )
-        mock_execute = mock.MagicMock(return_value=["a", "b"])
-        inspector.bind.execute = mock_execute
+        inspector.bind.execute.return_value.fetchall = mock.MagicMock(
+            return_value=["a", "b"]
+        )
         table_name = "table_name"
         result = PrestoEngineSpec._show_columns(inspector, table_name, None)
         assert result == ["a", "b"]
-        mock_execute.assert_called_once_with(f'SHOW COLUMNS FROM "{table_name}"')
+        inspector.bind.execute.assert_called_once_with(
+            f'SHOW COLUMNS FROM "{table_name}"'
+        )
 
     def test_show_columns_with_schema(self):
         inspector = mock.MagicMock()
         inspector.engine.dialect.identifier_preparer.quote_identifier = (
             lambda x: f'"{x}"'
         )
-        mock_execute = mock.MagicMock(return_value=["a", "b"])
-        inspector.bind.execute = mock_execute
+        inspector.bind.execute.return_value.fetchall = mock.MagicMock(
+            return_value=["a", "b"]
+        )
         table_name = "table_name"
         schema = "schema"
         result = PrestoEngineSpec._show_columns(inspector, table_name, schema)
         assert result == ["a", "b"]
-        mock_execute.assert_called_once_with(
+        inspector.bind.execute.assert_called_once_with(
             f'SHOW COLUMNS FROM "{schema}"."{table_name}"'
         )