Implement jrjackson -> jr_jackson alias for back-compat

lib/multi_json.rb

@@ -26,6 +26,10 @@ def default_options=(value)
     self.load_options = self.dump_options = value
   end
 
+  ALIASES = {
+    'jrjackson' => :jr_jackson
+  }
+
   REQUIREMENT_MAP = [
     ['oj',           :oj],
     ['yajl',         :yajl],
@@ -88,8 +92,10 @@ def use(new_adapter)
   def load_adapter(new_adapter)
     case new_adapter
     when String, Symbol
+      new_adapter = ALIASES.fetch(new_adapter.to_s, new_adapter)
       require "multi_json/adapters/#{new_adapter}"
-      MultiJson::Adapters.const_get(:"#{new_adapter.to_s.split('_').map{|s| s.capitalize}.join('')}")
+      klass_name = new_adapter.to_s.split('_').map(&:capitalize) * ''
+      MultiJson::Adapters.const_get(klass_name)
     when NilClass, FalseClass
       load_adapter default_adapter
     when Class, Module

spec/multi_json_spec.rb

@@ -163,4 +163,21 @@
       it_behaves_like 'JSON-like adapter', adapter
     end
   end
+
+  describe 'aliases' do
+    if jruby?
+      describe 'jrjackson' do
+        after{ expect(MultiJson.adapter).to eq(MultiJson::Adapters::JrJackson) }
+
+        it 'allows jrjackson alias as symbol' do
+          expect{ MultiJson.use :jrjackson }.not_to raise_error
+        end
+
+        it 'allows jrjackson alias as string' do
+          expect{ MultiJson.use 'jrjackson' }.not_to raise_error
+        end
+
+      end
+    end
+  end
 end