How to pass an instance variable to an RSpec shared example

The problem is that self within the example group is different from self within a before hook, so it’s not the same instance variable even though it has the same name.

I recommend you use let for cases like these:

# support/shared_examples.rb
shared_examples "a text field" do |field, fill, length|
  it "it should be long enough" do
    model.send("#{field}=", fill * length)
    model.should be_valid
  end
end

# company_spec.rb
describe Company do
  describe "when address2" do
    it_behaves_like "a text field", "address2", "a", Company.address2.limit do
      let(:model) { Company.new( init stuff here ) }
    end
  end
end