PhpUnit mock包含了类方法

I have two classes, ClassA, ClassB. In ClassA I have Method which call method from ClassB. For Example:

function functionInClassB($state)
{
  if ($state) {
    return true;
  } else {
    return false;
  }
}

function functionInClassA ()
{
  if (functionInClassB(1)) {
    return "Anything";
  }
}

Now, I want test functionInClassB with PhpUnit and I dont want functionInClassB ran. I want return value which I want. Sorry for my English, please help!!!