As per the buster documentation you should do something as follows:
var assert = buster.referee.assert;
var refute = buster.referee.refute;
assert.equals(42, 42);
refute.equals(42, 43);
In line with that your test-script.js
should look something as follows:
buster.testCase("Hello", {
"says hello to name var": function () {
var assert = buster.referee.assert;
assert.equals(hello("Fulvio"), "Hello Fulvio");
return;
}
});