Using RSpec Example Groups for Common Functionality

January 13th, 2010, by Aaron

I’m currently getting into using RSpec for testing our controllers on what is turning into a large project. It’s been more than handy because we have a lot of complex scoping to take into account whenever retrieving data. People don’t like to see other peoples’ financial data, mostly because it implies that someone is probably looking at theirs. With this in mind it’s more than important that we know the right data is going to the right places and hence the need for controller testing.

Now most of our controllers require the user to be logged in so writing tests to check this for every controller is annoying and time consuming, more than that it feels dirty. I think this is what some people call a code smell though I’m not up to speed on buzz words. There are also other tasks that are done quite often such as setting up the various types of users we’d like to test as, it would be nice if this were easily put in one place and could be easily pulled in. I guess I was looking for a template of tests that I could share.

It seems that the solution to it is found in Shared Example Groups which I hadn’t heard very much discussion about and it kind of leaves working out how they work to you rather than documenting it too much.

So far I’ve used it simply to make sure that controllers that require are redirecting users appropriately and also for setting up a specific type of user for our system before testing.

I created a directory under /spec/support called example_groups and in there I have a file called login_groups.rb. In that file I have something like the following :

shared_examples_for "customer is logged in" do
  before(:all) do
    @user = Factory(:customer_user)
    @user.customers.push Factory(:customer)
  end

  before(:each) do
    activate_authlogic
    OperatorSession.create(@operator)
  end
end

Now in my spec files when I have a bunch of tests requiring a logged in customer I will include this little snippet :

  it_should_behave_like "customer is logged in"

I get a logged in customer to start playing around with. I have the spec/support/example_groups directory in my include paths for Rspec and so it just all works.

My tests can then start to look like :

describe MerchantsController do
  it_should_behave_like "areas requiring login"

  context "customer logged in" do
    it_should_behave_like "customer is logged in"

    ... insert other tests here ...
  end
end

It means I can swap in another authentication gem/plugin pretty easily and also encapsulates the logic about creating customers, or whatever type of item you want to use, so that if that changes you can swap things in and out with a minimum of fuss.

Just to be clear, example groups aren’t limited to setup tasks or connecting to before/after hooks, you can also include a bunch of tests as well. This allows me to have a bunch of tests to run to make sure that a user does have to be logged in for various controllers and include these tests in on line.

I hope this helps someone, it took a bit of searching and trial and error myself this morning to get it working and find the uses for it that I’ve found. I’m definitely open to better solutions to this sort of issue though.

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2 Responses to “Using RSpec Example Groups for Common Functionality”

  1. pay tv says:

    I just got bitten by this, thanks for sharing. Will try the shared_examples_for method above.

  2. [...] Transcending Frontiers » Using RSpec Example Groups for Common … [...]

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