Use the last non-block arg for cop

In Ruby, the explicit block argument is special, and for our case cannot
be converted into a keyword argument. The argument we want instead is
the last non-block argument.

rubocop/cop/lint/last_keyword_argument.rb

@@ -16,7 +16,7 @@ module RuboCop
         KEYWORD_DEPRECATION_STR = 'maybe ** should be added to the call'
 
         def on_send(node)
-          arg = node.arguments.last
+          arg = get_last_argument(node)
           return unless arg
 
           return unless known_match?(processed_source.file_path, node.first_line, node.method_name.to_s)
@@ -44,6 +44,12 @@ module RuboCop
 
         private
 
+        def get_last_argument(node)
+          return node.arguments[-2] if node.block_argument?
+
+          node.arguments.last
+        end
+
         def known_match?(file_path, line_number, method_name)
           file_path_from_root = file_path.sub(File.expand_path('../../..', __dir__), '')
 

spec/rubocop/cop/lint/last_keyword_argument_spec.rb

@@ -95,6 +95,23 @@ RSpec.describe RuboCop::Cop::Lint::LastKeywordArgument do
       SOURCE
     end
 
+    it 'registers an offense on the last non-block argument' do
+      expect_offense(<<~SOURCE, 'create_service.rb')
+        users.call(id, params, &block)
+                       ^^^^^^ Using the last argument as keyword parameters is deprecated
+      SOURCE
+
+      expect_correction(<<~SOURCE)
+        users.call(id, **params, &block)
+      SOURCE
+    end
+
+    it 'does not register an offense if the only argument is a block argument' do
+      expect_no_offenses(<<~SOURCE, 'create_service.rb')
+        users.call(&block)
+      SOURCE
+    end
+
     it 'registers an offense and corrects by converting splat to double splat' do
       expect_offense(<<~SOURCE, 'create_service.rb')
         users.call(id, *params)