Is monkey patching PageObject::PageFactory#visit_page a good idea?

Question

A developer recently asked if our tests could execute some javascript every time a page is opened. See bug 44299 for more details.

Executing javascript is trivial:

browser.execute_script('return mw.loader.getModuleNames().filter(function (module) { return mw.loader.getState(module) === "error"; }).length === 0;')
#=> true 

We are using page-object's #visit_page to open pages. An easy way to make sure the javascript in the above example is executed every time a page is opened would be to monkey patch the #visit_page method.

alias_method chain (from question 4470108) looks like a simple way to do it.

Is there a better way?

Answer 1

You could simply create a method on your page object class named initialize_page. This method will be called immediately after the page loads. In that method you can make the call to execute_script (a method on the page) passing the javascript you wish to execute.

Answer 2

It seems to me like you are doing a bit too much work for something very simple. I'm not sure what framework you are using, but do you have an application wide JavaScript file? For a rails application I would write a test.js.erb:

<%= %q+browser.execute_script('return mw.loader.getModuleNames().filter(function (module) { return mw.loader.getState(module) === "error"; }).length === 0;')+ if Rails.env.test? %>

and add //= test to your application manifest