units: support mm

Closes #161

spec/api/api_units_spec.rb

@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+describe Squib::Deck do
+
+  let(:deck) { Squib::Deck.new }
+
+  context '#in' do
+    it 'converts inches properly' do
+      expect(deck.inches(1)).to eq 300
+    end
+
+    it 'handles strings too' do
+      expect(deck.inches('1')).to eq 300
+    end
+  end
+
+  context '#cm' do
+    it 'converts inches properly' do
+      expect(deck.cm(1)).to eq 118.1102361
+    end
+
+    it 'handles strings too' do
+      expect(deck.cm('1')).to eq 118.1102361
+    end
+  end
+
+  context '#mm' do
+    it 'converts inches properly' do
+      expect(deck.mm(1)).to eq 11.81102361
+    end
+
+    it 'handles strings too' do
+      expect(deck.mm('1')).to eq 11.81102361
+    end
+  end
+
+end