dont globally shim ruby2_keywords

spec/rspec/support/method_signature_verifier_spec.rb

@@ -1,8 +1,6 @@
 require 'rspec/support'
 require 'rspec/support/method_signature_verifier'
 
-def ruby2_keywords(*); end unless respond_to?(:ruby2_keywords, true)
-
 module RSpec
   module Support
     RSpec.describe 'verifying methods' do
@@ -12,16 +10,28 @@ def valid_non_kw_args?(arity)
         described_class.new(signature, [nil] * arity).valid?
       end
 
-      ruby2_keywords def valid?(*args)
-        described_class.new(signature, args).valid?
+      if RubyFeatures.kw_arg_separation?
+        ruby2_keywords def valid?(*args)
+          described_class.new(signature, args).valid?
+        end
+      else
+        def valid?(*args)
+          described_class.new(signature, args).valid?
+        end
       end
 
       def error_description
         described_class.new(signature).error_message[/Expected (.*),/, 1]
       end
 
-      ruby2_keywords def error_for(*args)
-        described_class.new(signature, args).error_message
+      if RubyFeatures.kw_arg_separation?
+        ruby2_keywords def error_for(*args)
+          described_class.new(signature, args).error_message
+        end
+      else
+        def error_for(*args)
+          described_class.new(signature, args).error_message
+        end
       end
 
       def signature_description