fix(BigQuery): explicitly quote columns in select_star (#16822)

* fix (BigQuery): explicitly quote columns in select_star

* Fix test

* Fix SELECT * in BQ

* Add unit tests

* Remove type changes

tests/unit_tests/db_engine_specs/test_bigquery.py

@@ -0,0 +1,190 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# pylint: disable=unused-argument, import-outside-toplevel, protected-access
+
+from flask.ctx import AppContext
+from pytest_mock import MockFixture
+from sqlalchemy import select
+from sqlalchemy.dialects.sqlite.base import SQLiteDialect
+from sqlalchemy.sql import sqltypes
+
+
+def test_get_fields(app_context: AppContext) -> None:
+    """
+    Test the custom ``_get_fields`` method.
+
+    The method adds custom labels (aliases) to the columns to prevent
+    collision when referencing record fields. Eg, if we had these two
+    columns:
+
+        name STRING
+        project STRUCT<name STRING>
+
+    One could write this query:
+
+        SELECT
+            `name`,
+            `project`.`name`
+        FROM
+            the_table
+
+    But then both columns would get aliased as "name".
+
+    The custom method will replace the fields so that the final query
+    looks like this:
+
+        SELECT
+            `name` AS `name`,
+            `project`.`name` AS project__name
+        FROM
+            the_table
+
+    """
+    from superset.db_engine_specs.bigquery import BigQueryEngineSpec
+
+    columns = [{"name": "limit"}, {"name": "name"}, {"name": "project.name"}]
+    fields = BigQueryEngineSpec._get_fields(columns)
+
+    # generic SQL
+    query = select(fields)
+    assert (
+        str(query)
+        == 'SELECT "limit" AS "limit", name AS name, "project.name" AS project__name'
+    )
+
+    # BigQuery-specific SQL
+    try:
+        from pybigquery.sqlalchemy_bigquery import BigQueryDialect
+    except ModuleNotFoundError:
+        return
+
+    assert str(query.compile(dialect=BigQueryDialect())) == (
+        "SELECT `limit` AS `limit`, `name` AS `name`, "
+        "`project`.`name` AS `project__name`"
+    )
+
+
+def test_select_star(mocker: MockFixture, app_context: AppContext) -> None:
+    """
+    Test the ``select_star`` method.
+
+    The method removes pseudo-columns from structures inside arrays. While these
+    pseudo-columns show up as "columns" for metadata reasons, we can't select them
+    in the query, as opposed to fields from non-array structures.
+    """
+    from superset.db_engine_specs.bigquery import BigQueryEngineSpec
+
+    cols = [
+        {
+            "name": "trailer",
+            "type": sqltypes.ARRAY(sqltypes.JSON()),
+            "nullable": True,
+            "comment": None,
+            "default": None,
+            "precision": None,
+            "scale": None,
+            "max_length": None,
+        },
+        {
+            "name": "trailer.key",
+            "type": sqltypes.String(),
+            "nullable": True,
+            "comment": None,
+            "default": None,
+            "precision": None,
+            "scale": None,
+            "max_length": None,
+        },
+        {
+            "name": "trailer.value",
+            "type": sqltypes.String(),
+            "nullable": True,
+            "comment": None,
+            "default": None,
+            "precision": None,
+            "scale": None,
+            "max_length": None,
+        },
+        {
+            "name": "trailer.email",
+            "type": sqltypes.String(),
+            "nullable": True,
+            "comment": None,
+            "default": None,
+            "precision": None,
+            "scale": None,
+            "max_length": None,
+        },
+    ]
+
+    # mock the database so we can compile the query
+    database = mocker.MagicMock()
+    database.compile_sqla_query = lambda query: str(
+        query.compile(dialect=SQLiteDialect())
+    )
+
+    # use SQLite dialect so we don't need the BQ dependency
+    engine = mocker.MagicMock()
+    engine.dialect = SQLiteDialect()
+
+    sql = BigQueryEngineSpec.select_star(
+        database=database,
+        table_name="my_table",
+        engine=engine,
+        schema=None,
+        limit=100,
+        show_cols=True,
+        indent=True,
+        latest_partition=False,
+        cols=cols,
+    )
+    assert (
+        sql
+        == """SELECT trailer AS trailer
+FROM my_table
+LIMIT ?
+OFFSET ?"""
+    )
+
+    # BigQuery-specific SQL
+    try:
+        from pybigquery.sqlalchemy_bigquery import BigQueryDialect
+    except ModuleNotFoundError:
+        return
+
+    database.compile_sqla_query = lambda query: str(
+        query.compile(dialect=BigQueryDialect())
+    )
+    engine.dialect = BigQueryDialect()
+
+    sql = BigQueryEngineSpec.select_star(
+        database=database,
+        table_name="my_table",
+        engine=engine,
+        schema=None,
+        limit=100,
+        show_cols=True,
+        indent=True,
+        latest_partition=False,
+        cols=cols,
+    )
+    assert (
+        sql
+        == """SELECT `trailer` AS `trailer`
+FROM `my_table`
+LIMIT :param_1"""
+    )