Add compatibility with Ruby 3

elasticsearch-model/lib/elasticsearch/model/proxy.rb

@@ -115,15 +115,18 @@ def initialize(target)
           @target = target
         end
 
-        # Delegate methods to `@target`
+        def ruby2_keywords(*) # :nodoc:
+        end if RUBY_VERSION < "2.7"
+
+        # Delegate methods to `@target`. As per [the Ruby 3.0 explanation for keyword arguments](https://www.ruby-lang.org/en/news/2019/12/12/separation-of-positional-and-keyword-arguments-in-ruby-3-0/), the only way to work on Ruby <2.7, and 2.7, and 3.0+ is to use `ruby2_keywords`.
         #
-        def method_missing(method_name, *arguments, &block)
+        ruby2_keywords def method_missing(method_name, *arguments, &block)
           target.respond_to?(method_name) ? target.__send__(method_name, *arguments, &block) : super
         end
 
         # Respond to methods from `@target`
         #
-        def respond_to?(method_name, include_private = false)
+        def respond_to_missing?(method_name, include_private = false)
           target.respond_to?(method_name) || super
         end
 

elasticsearch-model/spec/elasticsearch/model/proxy_spec.rb

@@ -31,6 +31,10 @@ def bar
         'insta barr'
       end
 
+      def keyword_method(foo: 'default value')
+        foo
+      end
+
       def as_json(options)
         {foo: 'bar'}
       end
@@ -98,7 +102,6 @@ def changes_to_save
   end
 
   context 'when instances are cloned' do
-
     let!(:model) do
       DummyProxyModel.new
     end
@@ -121,4 +124,9 @@ def changes_to_save
       expect(duplicate).to eq(duplicate_target)
     end
   end
+
+  it 'forwards keyword arguments to target methods' do
+    expect(DummyProxyModel.new.__elasticsearch__.keyword_method(foo: 'bar')).to eq('bar')
+  end
+
 end