chore(viz): remove legacy explore_json + viz.py pipeline (#41714)

Co-authored-by: Claude Code <noreply@anthropic.com>

tests/unit_tests/charts/data/test_empty_query_context.py

@@ -0,0 +1,43 @@
+# 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.
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+from superset.charts.schemas import ChartDataQueryContextSchema
+
+
+def test_query_context_schema_accepts_empty_queries(app_context: Any) -> None:
+    """
+    Charts that compose other charts (deck.gl Multiple Layers) issue no
+    query of their own: their buildQuery produces an empty ``queries``
+    list and every layer is fetched client-side. The schema must accept
+    that shape so the container chart can flow through /api/v1/chart/data,
+    and the processor must return an empty result list for it.
+    """
+    with patch(
+        "superset.common.query_context_factory.DatasourceDAO.get_datasource",
+        return_value=MagicMock(),
+    ):
+        query_context = ChartDataQueryContextSchema().load(
+            {
+                "datasource": {"id": 1, "type": "table"},
+                "queries": [],
+                "result_format": "json",
+                "result_type": "full",
+            }
+        )
+    assert query_context.queries == []