RSpec controller specs: any way to ensure controller instance variables do not cross over between multiple 'gets'

Question

Is there any way in a controller spec to 'reset' the instance variable space before each get if we have to do multiple gets in the same spec context?

I understand the one-assertion-per-test guideline. However, for one of our sets of tests, it runs about 3x faster if we don't do a separate (lengthy) before(:each) setup before each get and if we run a sequence of get/asserts together in a single context.

However, it seems that (unlike when controller methods are invoked via browser) if you do two consecutive get's with rspec, instance variables are not cleared with each get, so data crossover is possible.

Here's a failing test, showing that a variable set in 'vartest1' is still present when another controller method 'vartest2' is run:

Controller methods:

  def vartest1
    @this_var = "foo" 
    render :text => @this_var
  end

  def vartest2
    render :text => @this_var # should be EMPTY!
  end

Rspec controller spec:

  describe "instance variable crossover example", :focus => true do
    describe "THIS PASSES put each get in separate contexts" do
      it "vartest1 outputs foo" do
        get "vartest1"
        response.body.should include("foo")
      end
      it "vartest2 does NOT output foo" do
        get "vartest2"
        response.body.should_not include("foo")
      end
    end
    describe "THIS FAILS put both gets in SAME context" do
      it "should not crossover controller instance varables" do
        get "vartest1"
        response.body.should include("foo")
        get "vartest2"
        response.body.should_not include("foo") # THIS FAILS
      end
    end
  end

Rspec results:

 instance variable crossover example
    THIS PASSES put each get in separate contexts
      vartest1 outputs foo
      vartest2 does NOT output foo
    THIS FAILS put both gets in SAME context
      should not crossover controller instance varables (FAILED - 1)

What's happening in the failing test is that when rspec does get 'vartest1' the controller method set an instance variable to 'foo', and when rspec does get 'vartest2' the instance variable (which should be nil) is still set, so the test fails.

If you want to avoid speed issues with a lengthy before(:each) block I'd suggest using let instead, which is lazy-evaluated. Putting multiple get requests in a single spec is a bad idea. — Chris Salzberg
– Chris Salzberg, Commented Jan 4, 2013 at 2:49

zetetic · Accepted Answer · 2013-01-04 03:12:54Z

2

Controller specs are unit tests. Like all unit tests, they should test methods in isolation. For controllers, this means each action needs its own specs(s). Performing multiple requests in a controller spec is not likely to get you anywhere.

You might consider using a request spec, or Cucumber. Depending on your environment, this might get you better results, since the setup would only need to happen once per example. You could then do multiple gets (or visits).

Another possibility is to use mocks/stubs for your controller specs. This can improve performance significantly, at the price of doing additional setup. The RSpec scaffold examples for controller specs are a good starting point for this approach.

answered Jan 4, 2013 at 3:12

zetetic

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