Help testing helpers
Posted by rick Wed, 08 Feb 2006 21:31:00 GMT
Ruby on Rails is big on testing. There’s support for unit testing cooked right in—every time you create a model you get the unit testing framework built for free—just fill in the blanks. Similarly, whenever you create a new controller, you get the functional testing framework built for free—just fill in the blanks. Seems like view testing (with Selenium and OpenQA) is moving forward, and I wonder if some sort of automated support for those won’t come from the Rails framework itself soon…
That said, there’s very little talk about testing helpers—those bits of Ruby code that are made available for use by the view, but which aren’t in the templates themselves. Helpers aid reuse, and are a valuable use of Ruby behind the template.
Certain helpers can be tested with test/unit, just like unit tests for models. Some helpers, though, call functionality in the view libraries: a really common idiom is to provide various foo_link() methods that will generate links to certain types of objects. Rather than repeating the same detailed ActionView link_to() call everywhere, the code is factored out to a helper method which assembles the appropriate information and calls link_to() for you. Then you’ve got a single point of change whenever you want to change how comment links, story links, user links, whatever, behave.
Testing this sort of code should require a functional test, since you’ll actually want to have the view instantiated. There’s seemingly zero documentation on how to do this, and, checking around on some existing Ruby projects, I see people writing these sorts of helpers, but I see noone actually testing them.
We’ve jumped back for a moment and are relying on “stub” code to allow us to get a primitive, but less than ideal, test of our link helper (and other similar helpers that call ActionView functionality). We’re now looking for guidance from the Rails community.
To that end, we’ve posted Rails ticket #3775.
