You in japanese

This has been a mystery for the longest time to students who learn japanese including me, some teacher tell me it is ok to use anata and some say it is not, most say it is not so I try not to say it at all but it's hard.

For example: "anata no tesuto wa genki desu ka"

how can I say this without using anata? is it ok to use anata?

Thank you for help.

Tesuto is a name of pet or something?
Yes, "tesuto wa genki (desu ka)?" is not very polite but good.

In many cases, you can omit the subject words in Japanese.
But if you're unsure, you don't have to do.
It's OK to use anata.

what is a tesuto and why would it be genki?

If (s)he is a living being that belongs to someone other than yourself, you should put a -san or -chan at the end, and that almost automatically implies that the being belongs to the "you". You could also use polite form to add the emphasis.

Examples:

(If Tesuto is a pet or small child of "you")
Tesuto-chan wa genki desuka?

(If Tesuto is a teenager or older)
Tesuto-san wa o-genki desuka?

But maybe you wanted to say "How did your examination go?" In that case, you can say;

Tesuto wa dou-deshita ka?

Since you're asking the examination results to "you" the examination is apparently not what you yourself took. The "you" person might wonder if this is about an exam that "you" took or what "you"'s brother took, but it's natural to assume that it's the one "you" took.

testo is test as an exam.

I was asking if the test went well for the person.

テストの結果はどうですか？
or
テストの結果はどうでしたか？

in most of conversation, "you" is omitted, if it is clear.