Unit Testing Assistance (Jasmine)

I am trying to write some unit tests for the following JS file, I am really struggling as none of them actually return values, plus I am new to unit testing, some assistance and example tests would be extremely useful as I am really struggling at the moment.

 //FILE 1 --------------------------------------------------
 // Declare all the product prices in an associative array
 var prices = new Array();
 prices["unflav-1"] = 12.69;
 prices["flav-1"] = 15.79;
 prices["unflav-2.5"] = 26.49;
 prices["flav-2.5"] = 31.19;
 prices["unflav-5"] = 46.79;
 prices["flav-5"] = 57.19;

 // Declare the colours for flavours in an associative array
 var flavourColours = new Array();
 flavourColours["Unflavoured"] = {
 background: "#ead9ed",
 border: "#8c828e"
 };

 flavourColours["Chocolate"] = {
 background: "#D2691E",
 border: "#2a1506"
 };
 flavourColours["Banana"] = {
 background: "#FFFF00",
 border: "#666600"
 };
 flavourColours["Strawberry"] = {
 background: "#FF0000",
 border: "#7f0000"
 };
 flavourColours["Cookies & Cream"] = {
 background: "#B57E1D",
 border: "#48320b"
 };


 //
 function formChange() {
   // get value and name for flavour, package and amount
   var flavourElem = document.getElementById('flavour-select');

   var flavourValue = flavourElem.value;
   var flavour = flavourElem.options[flavourElem.selectedIndex].text;
   var packageValue = document.getElementById('package-select').value;
   var amountValue = document.getElementById('amount-select').value;

   // lookup price in array then change the price on screen
   document.getElementById('product-price').innerHTML = prices[flavourValue + '-' + amountValue];


  // update graphical visualisation for flavour and amount
  document.getElementById('chosen-flavour-colour').style.backgroundColor = flavourColours[flavour].background;
  var border = "3px solid " + flavourColours[flavour].border;
  document.getElementById('chosen-flavour-colour').style.border = border;
  document.getElementById('chosen-flavour-text').innerHTML = flavour;
  var ref = "img/" + amountValue + "kg-weight.png";
  document.getElementById('chosen-weight-visual').style.backgroundImage = "url(" + ref + ")";
 }