spec.rb

describe "Foo" do
  before do
    allow_any_instance # ... user thing
    allow_any_instance_of(Event).to receive(:resource_visible) { resource_visible }
  end
  
  let(:perform!) { get "etc" }
  
  context "with an event invisible to both" do
    let(:resource_visible) { true }
    it "returns 404" do
      perform!
      expect(response) # ...
    end
  end
end