MongoDB (Java) if statement equals value

So I'm working on a piece of code with a if statement and in the if statement i want to check if a value of my MongoDB equals "test"

I currently have this it isn't much but i really don't know how to do this

  if (DBManager.getInstance().getTestCollection()) {

Example of my MongoDB

{
"_id": {
    "$oid": "56fd47ea18de75129095d841"
},
"foo": "test"
}