2 files changed, 34 insertions, 2 deletions
diff --git a/lib/zero/renderer.rb b/lib/zero/renderer.rb
index 3be7d6e..740d156 100644
--- a/lib/zero/renderer.rb
+++ b/lib/zero/renderer.rb
@@ -76,8 +76,8 @@ module Zero
     # @api private
     # @param string [String] the original type name
     # @return [String] the shorter representation or the original
-    def transform(string)
-      return map[string] if map.has_key?(string)
+    def self.transform(string)
+      return type_map[string] if type_map.has_key?(string)
       string
     end
 
diff --git a/spec/unit/renderer/transform_spec.rb b/spec/unit/renderer/transform_spec.rb
new file mode 100644
index 0000000..fce6730
--- /dev/null
+++ b/spec/unit/renderer/transform_spec.rb
@@ -0,0 +1,32 @@
+require 'spec_helper'
+
+describe Zero::Renderer, '.transform' do
+  subject { Zero::Renderer }
+  let(:map) {{ 'text/html' => 'html' }}
+
+  shared_examples_for 'a transformer' do
+    before :each do
+      Zero::Renderer.type_map = map
+    end
+
+    after :each do
+      Zero::Renderer.type_map = {}
+    end
+
+    it "transforms a string" do
+      subject.transform(original).should eq(result)
+    end
+  end
+
+  context "with a shortable type" do
+    let(:original) { 'text/html' }
+    let(:result) { 'html' }
+    it_behaves_like 'a transformer'
+  end
+
+  context "with an unshortable type" do
+    let(:original) { 'application/json' }
+    let(:result) { 'application/json' }
+    it_behaves_like 'a transformer'
+  end
+end