If you try to run the configureFailPoint command without test commands enabled, you get the following error message:

> db.adminCommand({configureFailPoint: 'disableMatchExpressionOptimization', 'mode': 'off'})
{
	"ok" : 0,
	"errmsg" : "no such command: 'configureFailPoint'",
	"code" : 59,
	"codeName" : "CommandNotFound"
} 

It would be better if the message told you to enable test commands in order to run that command.