Add ruby2_keywords to delegating methods (#62)

* Add ruby2_keywords to delegating methods
* Fix unit tests for Ruby 1.9

lib/docile.rb

@@ -44,6 +44,8 @@ def dsl_eval(dsl, *args, &block)
     exec_in_proxy_context(dsl, FallbackContextProxy, *args, &block)
     dsl
   end
+
+  ruby2_keywords :dsl_eval if respond_to?(:ruby2_keywords, true)
   module_function :dsl_eval
 
   # Execute a block in the context of an object whose methods represent the
@@ -83,6 +85,8 @@ def dsl_eval(dsl, *args, &block)
   def dsl_eval_with_block_return(dsl, *args, &block)
     exec_in_proxy_context(dsl, FallbackContextProxy, *args, &block)
   end
+
+  ruby2_keywords :dsl_eval_with_block_return if respond_to?(:ruby2_keywords, true)
   module_function :dsl_eval_with_block_return
 
   # Execute a block in the context of an immutable object whose methods,
@@ -120,5 +124,7 @@ def dsl_eval_with_block_return(dsl, *args, &block)
   def dsl_eval_immutable(dsl, *args, &block)
     exec_in_proxy_context(dsl, ChainingFallbackContextProxy, *args, &block)
   end
+
+  ruby2_keywords :dsl_eval_immutable if respond_to?(:ruby2_keywords, true)
   module_function :dsl_eval_immutable
 end

lib/docile/chaining_fallback_context_proxy.rb

@@ -16,5 +16,7 @@ class ChainingFallbackContextProxy < FallbackContextProxy
     def method_missing(method, *args, &block)
       @__receiver__ = super(method, *args, &block)
     end
+
+    ruby2_keywords :method_missing if respond_to?(:ruby2_keywords, true)
   end
 end

lib/docile/execution.rb

@@ -36,6 +36,8 @@ def exec_in_proxy_context(dsl, proxy_type, *args, &block)
         end
       end
     end
+
+    ruby2_keywords :exec_in_proxy_context if respond_to?(:ruby2_keywords, true)
     module_function :exec_in_proxy_context
   end
 end

lib/docile/fallback_context_proxy.rb

@@ -61,6 +61,8 @@ def initialize(receiver, fallback)
             end
           end
 
+        singleton_class.send(:ruby2_keywords, :method_missing) if singleton_class.respond_to?(:ruby2_keywords, true)
+
         # instrument a helper method to remove the above instrumentation
         singleton_class.
           send(:define_method, :__docile_undo_fallback__) do
@@ -94,6 +96,7 @@ def method_missing(method, *args, &block)
         end
       end
     end
+
     ruby2_keywords :method_missing if respond_to?(:ruby2_keywords, true)
   end
 end

spec/docile_spec.rb

@@ -465,6 +465,47 @@ def set(v0, v1:, v2:)
         end
       end
     end
+
+    if RUBY_VERSION >= "2.0.0"
+      context "when a DSL method has a double splat" do
+        class DSLMethodWithDoubleSplat
+          attr_reader :arguments, :options
+
+          # Use class_eval because Ruby 1.x does not support double splat
+          class_eval <<-METHOD, __FILE__, __LINE__ + 1
+            def configure(*arguments, **options)
+              @arguments = arguments.dup
+              @options = options.dup
+            end
+          METHOD
+        end
+
+        let(:dsl) { DSLMethodWithDoubleSplat.new }
+
+        it "correctly passes keyword arguments" do
+          Docile.dsl_eval(dsl) { configure(1, a: 1) }
+
+          expect(dsl.arguments).to eq [1]
+          expect(dsl.options).to eq({ a: 1 })
+        end
+
+        if RUBY_VERSION >= "3.0.0"
+          it "correctly passes hash arguments on Ruby 3+" do
+            Docile.dsl_eval(dsl) { configure(1, { a: 1 }) }
+
+            expect(dsl.arguments).to eq [1, { a: 1 }]
+            expect(dsl.options).to eq({})
+          end
+        elsif RUBY_VERSION >= "2.0.0"
+          it "correctly passes hash arguments on Ruby 2" do
+            Docile.dsl_eval(dsl) { configure(1, { a: 1 }) }
+
+            expect(dsl.arguments).to eq [1]
+            expect(dsl.options).to eq({ a: 1 })
+          end
+        end
+      end
+    end
   end
 
   describe ".dsl_eval_with_block_return" do