Update unit tests to cover dual header functionality

spec/unit/generator/xcconfig/aggregate_xcconfig_spec.rb

@@ -55,6 +55,11 @@ module Pod
           @xcconfig.to_hash['PODS_ROOT'].should == '${SRCROOT}/Pods'
         end
 
+        it 'adds the sandbox public headers search paths to the xcconfig, with quotes, as header search paths' do
+          expected = "\"#{config.sandbox.public_headers.search_paths.join('" "')}\""
+          @xcconfig.to_hash['HEADER_SEARCH_PATHS'].should == expected
+        end
+
         it 'adds the sandbox public headers search paths to the xcconfig, with quotes, as system headers' do
           expected = "$(inherited) \"-isystem#{config.sandbox.public_headers.search_paths.join('" -isystem"')}\""
           @xcconfig.to_hash['OTHER_CFLAGS'].should == expected