add Hash method compat layer

lib/hashr.rb

@@ -1,5 +1,7 @@
+require 'hashr/core_ext/ruby/hash'
+
 class Hashr < BasicObject
-  require 'hashr/core_ext/ruby/hash'
+  require 'hashr/delegate/conditional'
   require 'hashr/env'
 
   class << self

lib/hashr/delegate/conditional.rb

@@ -0,0 +1,13 @@
+class Hashr
+  module Delegate
+    module Conditional
+      def method_missing(name, *args, &block)
+        if (args.any? || block) && @data.respond_to?(name)
+          @data.send(name, *args, &block)
+        else
+          super
+        end
+      end
+    end
+  end
+end

lib/hashr/delegate/hash.rb

@@ -0,0 +1,48 @@
+class Hashr
+  module Delegation
+    module Hash
+      METHODS = [
+        :all?,
+        :any?,
+        :clear,
+        :delete,
+        :delete_if,
+        :detect,
+        :drop,
+        :drop_while,
+        :each,
+        :empty?,
+        :fetch,
+        :find,
+        :flat_map,
+        :grep,
+        :group_by,
+        :hash,
+        :inject,
+        :invert,
+        :is_a?,
+        :keep_if,
+        :key,
+        :key?,
+        :keys,
+        :length,
+        :map,
+        :merge,
+        :nil?,
+        :none?,
+        :one?,
+        :reduce,
+        :reject,
+        :select,
+        :size,
+        :value?,
+        :values,
+        :values_at
+      ]
+
+      METHODS.each do |name|
+        define_method(name) { |*args, &block| @data.send(name, *args, &block }
+      end
+    end
+  end
+end

spec/hashr/delegate/conditional_spec.rb

@@ -0,0 +1,19 @@
+describe Hashr::Delegate::Conditional do
+  let(:klass) { Class.new(Hashr) { include Hashr::Delegate::Conditional } }
+
+  it 'delegates key?' do
+    hashr = klass.new(foo: 'foo')
+    expect(hashr.key?(:foo)).to eq(true)
+  end
+
+  it 'delegates select' do
+    hashr = klass.new(foo: 'foo', bar: 'bar')
+    expect(hashr.select { |key, value| key == :bar }.to_h).to eq(bar: 'bar')
+  end
+
+  it 'delegates delete' do
+    hashr = klass.new(foo: 'foo', bar: 'bar')
+    hashr.delete(:foo)
+    expect(hashr.to_h).to eq(bar: 'bar')
+  end
+end