How do HR know about motivation level of an employee before investing on an employee through a training program?

We must work for employees test to measure ambitious goals and skills to be evaluated and find out the training needs of the employee before being sent to training courses

Here we go "communication" is the Key.
You need to classify employees on their career ambitions.
Different age group employees have different career ambitions that have to be considered before you make any training plans.
Indeed, dont just organize trainings to complete the mandated trainign hours, which is just wastage of all resources Some guys at40 thinks that they have reached in a point and no learning can do any better to them.
For these guys, if you can show them how can the employee be refreshed Career wise (monetary benefits, etc) they will be motivated.
It is difficult to motivate personnel who are assumes their learning skills are dead.
No company should invest single penny on such guys.
They eventually have to go out of the organization, due to obvious reasons. 

I'm not an HR guy but one thing I know is that quantitative performance will tell how motivated an employee is.
The more motivated he is, the more he perform well in his job.
What get measures get done.
Training is an investment.
You have to invest on your employee and give him proper training if needed.
After his training, access his performance (quantitative and qualitative) and you will see if it is effective or not.
As I said before it's an investment (like stock market), you may either get profit or not.
I hope it answer your question.

Thank you Jomar Pagtakhan for answer, after reading your answer a scenerio has pop up in my mind that is "If an employee of age40 years is experienced / expert on a skill, ofcourse his performance on that skill is excellent in an employee point of view and after Training Need Assessment (TNA) few key areas highlited for training, but employee don't think so, HERE HOW DO A COMPANY KNOW MOTIVATION LEVEL FOR TRAINING? not for regular assignments"