add hash slice using IndifferentAccess hashie#529

CHANGELOG.md

@@ -36,6 +36,7 @@ Any violations of this scheme are considered to be bugs.
 ### Fixed
 
 * [#516](https://github.com/hashie/hashie/issues/516): Fixed `NoMethodError` raised when including `Hashie::Extensions::Mash::SymbolizeKeys` and `Hashie::Extensions::SymbolizeKeys` in mashes/hashes with non string or symbol keys - [@carolineartz](https://github.com/carolineartz).
+* [#](): Fixed [slice doesn't work using symbols](https://github.com/hashie/hashie/issues/529) using hash with `IndifferentAccess` extension - [@gnomex](https://github.com/gnomex)
 * Your contribution here.
 
 ### Security

lib/hashie/extensions/indifferent_access.rb

@@ -141,6 +141,11 @@ def merge!(*)
         super.convert!
       end
 
+      def slice(*keys)
+        string_keys = keys.map { |key| convert_key(key) }
+        super(*string_keys)
+      end
+
       protected
 
       def hash_lacking_indifference?(other)

spec/hashie/extensions/indifferent_access_spec.rb

@@ -315,6 +315,16 @@ def indifferent_writer(key, value)
         end
       end
     end
+
+    describe '#slice' do
+      let(:h) { subject.build(foo: 'bar', baz: 'qux') }
+
+      it 'indifferently slices the hash' do
+        sliced_h = {'foo' => 'bar'}
+        expect(h.slice('foo')).to eq sliced_h
+        expect(h.slice(:foo)).to eq sliced_h
+      end
+    end
   end
 
   describe 'with merge initializer' do