sample.coffee

casper = require('casper').create()

casper.test.begin "Check for dataLayer on product page", 1, (test) ->
  casper.start 'http://local.build.com/k-690/p173354', ->
    test.assertEval ->
      typeof window.dataLayer.productId != "undefined"
    , 'Does dataLayer.productId exist?'
    test.assertEvalEquals ->
      window.dataLayer.productId
    , "K-690", 'Is the value of dataLayer.productId "K-690"?'
  casper.run ->
    test.done()