testing.js

// in the test code:

it("updates the page title on click", function() {
  assert.equals(view.find("h1").text(), "before update");
  
  view.find("button").trigger("click"); // uh oh-async!
  
  assert.equals(view.find("h1").text(), "after update"); // will fail due to callback being part of different stack
});

// in the view itself:

button.onclick = function(e) {
  setTimeout(function() {
    header.innerHTML = "after update";
  }, 500);
}