The following are the same specs (taken from here: http://jweden.tumblr.com/post/66999796589/async-testing-in-jasmine-2-0 ), working one in Javascript, the other, converted to Coffeescript (with js2coffee). The JS passes, the Coffeescript fails.

fails.coffee

describe "Asynchronous specs", ->
  funcRunInBackground = ->
    value = 1
    return
  wrapFuncRunInBackground = (done) ->

    # setup for simmulating the async operation, a function run in the background
    setTimeout (->
      funcRunInBackground()
      done()
      return
    ), 3000
    return
  value = 0
  beforeEach (done) ->
    wrapFuncRunInBackground done
    console.log "wrap function returns immediately but value = 1 is set 3 seconds later. value is still " + value
    return

  it "should support async execution of test preparation", ->
    expect(value).toBeGreaterThan 0
    return

  return

passes.coffee

describe "Asynchronous specs", ->
  
  ###########################
  # This needs to go HERE.  #
  ###########################
   
  value = 0

  funcRunInBackground = ->
    value = 1
    return
  wrapFuncRunInBackground = (done) ->

    # setup for simmulating the async operation, a function run in the background
    setTimeout (->
      funcRunInBackground()
      done()
      return
    ), 3000
    return

  beforeEach (done) ->
    wrapFuncRunInBackground done
    console.log "wrap function returns immediately but value = 1 is set 3 seconds later. value is still " + value
    return

  it "should support async execution of test preparation", ->
    expect(value).toBeGreaterThan 0
    return

  return

passes.js

describe("Asynchronous specs", function() {
  var value = 0;

  function funcRunInBackground() {
    value = 1;
  };  

  function wrapFuncRunInBackground(done) {
    // setup for simmulating the async operation, a function run in the background
    setTimeout(function() {
        funcRunInBackground();
        done();
    }, 3000);       
  }    

  beforeEach(function(done) {
      wrapFuncRunInBackground(done);    
      console.log("wrap function returns immediately but value = 1 is set 3 seconds later. value is still " + value);  
  });                 


  it("should support async execution of test preparation", function() {
    expect(value).toBeGreaterThan(0);
  });
});