add volunteers helper

spec/helpers/format_helper_spec.rb

@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe FormatHelper, type: :helper do
+
+  describe 'markdown' do
+    it 'should return empty string for nil' do
+      expect(markdown(nil)).to eq ''
+    end
+
+    it 'should return HTML for header markdown' do
+      expect(Redcarpet::Markdown).to receive(:new).
+        with(Redcarpet::Render::HTML, autolink: true,
+                                      space_after_headers: true,
+                                      no_intra_emphasis: true).
+        and_call_original
+
+      expect(markdown('# this is my header')).to eq "<h1>this is my header</h1>\n"
+    end
+  end
+end