Shoulda: How would I use an instance variable outside of a setup or should block?

I'm trying to do something like the following:

@special_attributes = Model.new.methods.select # a special subset
@special_attributes.each do |attribute|
  context "A model with #{attribute}" do
    setup do
      @model = Model.new
    end
    should "respond to it by name" do
      assert_respond_to @model, attribute
    end
  end
end

However, @special_attributes is out of scope when running the unit tests, leaving me with a nil object on line 2. I can't figure out where/how to define it to brin开发者_如何学运维g it in scope. Any thoughts?

Got it (I think). Shoulda is executing the block in the context of Shoulda::Context. In the above case, @special_attributes is an instance variable of my test class, not Shoulda::Context. To fix this, instead of using instance variables, just use local variables in the context block.

So, for example:

context "Model's" do
  model = Model.new
  special_attributes = model.methods.select # a special subset
  special_attributes.each do |attribute|

    context "attribute #{attribute}" do
      setup do
        @model = model
      end
      should "should have a special characteristic"
        assert_respond_to @model, attribute
        ...
      end
    end

  end
end