sketch spec approach

Example how the whole spec suite could be run three times for the
different implementations.

Alternatively, a very restricted set (2 or 3 examples) could be
used for the sister implementations, with the trust coming
from the correct well-speced implementation of link_to .

spec/rubocop/cop/rails/link_to_blank_spec.rb

@@ -1,6 +1,18 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::Cop::Rails::LinkToBlank, :config do
+  ['link_to', 'link_to_if condition?, ', 'link_to_unless condition?, '].each do |link_helper_method|
+    context "with '#{link_helper_method}'" do
+      context 'when not using target _blank' do
+        it 'does not register an offense' do
+          expect_no_offenses(<<~RUBY)
+            #{link_helper_method} 'Click here', 'https://www.example.com'
+          RUBY
+        end
+      end
+    end
+  end
+
   context 'when not using target _blank' do
     it 'does not register an offense' do
       expect_no_offenses(<<~RUBY)