First, we have the DAP API schema endpoint
/query/{namespace}/table/{table}/schema
which returns the JSON schema for each table that you can directly validate the output against.
Second, we also publish a recommended table structure for database engines PostgreSQL, MySQL and Microsoft SQL Server.
In our own internal integration tests, we create the database structure as per the referenced SQL scripts, and then ingest data and verify that all output rows for all database tables are successfully inserted or updated. Should there be a schema violation, the respective INSERT INTO ... or UPDATE ... SQL statement would fail.