"need all privileges" error message is difficult to investigate

[mrigger]

I wanted to start experimenting with SOAR, and started by connecting it to a MySQL database after creating a new user:

CREATE USER 'soar'@'localhost' IDENTIFIED BY 'soar';
GRANT ALL PRIVILEGES ON *.* TO 'soar'@'localhost';
FLUSH PRIVILEGES;

I then issued the following command:

echo "select * FROM t0;" | ./soar -test-dsn="soar:password@127.0.0.1:3306/test" -allow-online-as-test  -check-config
test-dsn: soar:password@tcp(127.0.0.1:3306)/test?charset=utf8, need all privileges

I didn't really know how to proceed from there, since the "need all privileges" information message did not help me much. I eventually found a useful hint by adjusting the log level ( -log-level 7) and noticing the following log entry:

2021/05/06 21:23:21.466 [D] [mysql.go:92]  Execute SQL with DSN(127.0.0.1:3306/test) : select concat(Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Reload_priv,Shutdown_priv,Process_priv,File_priv,Grant_priv,References_priv,Index_priv,Alter_priv,Show_db_priv,Super_priv,Create_tmp_table_priv,Lock_tables_priv,Execute_priv,Repl_slave_priv,Repl_client_priv,Create_view_priv,Show_view_priv,Create_routine_priv,Alter_routine_priv,Create_user_priv,Event_priv,Trigger_priv,Create_tablespace_priv,Create_role_priv,Drop_role_priv) from mysql.user where user='soar' and host='localhost'

As indicated by the output below, the Grant_priv was missing. I could address this by setting the privileges with GRANT ALL PRIVILEGES ON *.* TO 'soar'@'localhost' WITH GRANT OPTION;, after which connecting to the database worked.

+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| concat(Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Reload_priv,Shutdown_priv,Process_priv,File_priv,Grant_priv,References_priv,Index_priv,Alter_priv,Show_db_priv,Super_priv,Create_tmp_table_priv,Lock_tables_priv,Execute_priv,Repl |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| YYYYYYYYYYNYYYYYYYYYYYYYYYYYYYY                                                                                                                                                                                                                                 |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

Perhaps, if the connection fails, the output from the query above could be parsed and used to create an informative error message? I think this could greatly help other users that want to test SOAR and don't use the WITH GRANT option.