Rails 4 - assert_select not working with element updated by javascript

Question

I have a span element that is blank by default and updated when the page is loaded by javascript. This works great - however assert_select seems only able to get the initial HTML - BEFORE the page is finished loading. Is this the expected behavior? What am I doing wrong?

span element in a scaffold generated _form.html.erb:

...
<span id="confirm_loaded"></span>
...

---- In a .js file in app/assets/javascripts:

$(function(){
  $("#confirm_loaded").html("test");
});

---- When I load the page -- the page is updated via javascript and all is well.

However, in an integration test - this line:

assert_select "span#confirm_loaded", {text: "test"}

fails with the error:

<test> expected but was
<>..
Expected 0 to be >= 1.

which appears to confirm that the test isn't seeing the updated HTML element set by javascript (perhaps it's running before the page is fully loaded?)

A quick change to the page, remove the javascript and hardcode the HTML:

...
<span id="confirm_loaded">test</span>
...

And now the test passes (the assert_select is able to get the value and we're golden).

Is assert_select only able to get the initial value of HTML tags? Why is the assert_select not getting values updated by javascript as the page loads?

Thanks for your help.

Answer 1

Yes , you said right in you question. assert_select selects elements and makes equality tests on @response(@response.body) object. That's the actual response returned form server, so at that time no javascript code has executed so you get span with empty text. As scripts runs in your browser.

Answer 2

Thinking through this a bit, it could simply be the case that the command line tests are getting the response from the server and offering it up for parsing / verification.

This would have two important aspects:

1. Scripts & client-side code would not be executed
2. Enter on to the scene - testing frameworks that offer up browser interfaces, etc - so that client-side code gets rendered

Seems like this is the case - but - I'll leave the question open in case I'm missing something.