Refactoring out the unit conversion to its own place

lib/squib/args/unit_conversion.rb

@@ -0,0 +1,21 @@
+require 'squib/constants'
+
+module Squib
+  module Args
+    module UnitConversion
+
+      module_function
+      def parse(arg, dpi=300)
+        case arg.to_s.rstrip
+        when /in$/ #ends with "in"
+          arg.rstrip[0..-2].to_f * dpi
+        when /cm$/ #ends with "cm"
+          arg.rstrip[0..-2].to_f * dpi * INCHES_IN_CM
+        else
+          arg
+        end
+      end
+
+    end
+  end
+end

lib/squib/input_helpers.rb

@@ -1,4 +1,5 @@
 require 'squib/constants'
+require 'squib/args/unit_conversion'
 
 module Squib
   # :nodoc:
@@ -200,12 +201,7 @@ module Squib
       Squib::UNIT_CONVERSION_PARAMS.each_pair do |param_name, api_param|
         if needed_params.include? param_name
           opts[api_param].each_with_index do |arg, i|
-            case arg.to_s.rstrip
-            when /in$/ #ends with "in"
-              opts[api_param][i] = arg.rstrip[0..-2].to_f * @dpi
-            when /cm$/ #ends with "cm"
-              opts[api_param][i] = arg.rstrip[0..-2].to_f * @dpi * Squib::INCHES_IN_CM
-            end
+            opts[api_param][i] = Args::UnitConversion.parse(arg, @dpi)
           end
         end
       end

spec/args/unit_conversion_spec.rb

@@ -0,0 +1,22 @@
+require 'spec_helper'
+require 'squib/args/unit_conversion'
+
+describe Squib::Args::UnitConversion do
+
+  it 'does nothing on just numbers'  do
+    expect(subject.parse(20)).to eq(20)
+  end
+
+  it 'strips trailing whitespace'  do
+    expect(subject.parse('1in ')).to eq(300)
+  end
+
+  it 'is ok w/internal whitesapce' do
+    expect(subject.parse('1 in')).to eq(300)
+  end
+
+  it 'does cm'                      do
+    expect(subject.parse('1cm')).to eq(118.1102361)
+  end
+
+end