According to reformed theology, are _all_ wealthy Christians required to give their wealth to the poor? In Mark 10:17-31, we see Jesus talk to the rich young ruler, and tell him to sell his possessions and give it to the poor.

According to reformed theologians, is this required of all wealthy followers of Christ, or was this merely a test designed for this particular rich young ruler, to show that in his heart, he loved his wealth more than he loved God?

For those arguing the case of "no, wealthy Christinas are not required to give all their wealth to the poor" please explain how to handle verses like Mark 10:31, and 1 John 3:17.

For those arguing the case of "yes, wealthy Christians are required to give all their wealth to the poor", please explain how to handle the wealth of Job / Abraham, as well as why Zacchaeus, upon giving half his wealth to the poor and repaying 4 fold (did this bankrupt him?) earned the praise of Christ.
It's important to note that the Mark passage records Jesus telling one specific person to sell all his possessions and give to the poor.  Jesus did not give this command to all people in all times.  

It is inappropriate to take everything Jesus ever said to any person and attempt to apply it to all people for all times.  If we did that, then all of us would be under obligation to go into Jerusalem to get a donkey, throw our nets on the other side of the boat, get out of the boat and walk on water, and fill jars with water in order to get wine.

Jesus' direct command to the rich young ruler applied to that person.  Jesus, in His omniscience, may have understood that this man's wealth would be an insurmountable obstacle to his faith.  We don't know for sure, of course.

Generosity, as you reference in 1 John 3:17, is, however, commanded of all of those who are rich in this world and who are following Jesus.  

It should be noted that a man who is wealthy and continues to grow his wealth over time can actually give exceedingly more and care for more poor people than a wealthy man who gives everything he has at a single point in time.  

For instance, a man with $1 million could give it all away at one moment in time and help a certain amount of people.  Another man with $1 million, earning a 10% return on his investments, could give 100% of the increase a year in perpetuity.  That's $100,000 a year.  Ten years later, he's given $1 million and can continue giving for another ten or twenty or thirty years or more.  

The command is not to become poor, but to be generous.  Money is not the root of all evil--only the love of money.