add test for symbol type

spec/unit/kansen/mapper/note_parser_spec.rb

@@ -28,5 +28,9 @@
       expect(Kansen::Mapper::NoteParser.parse('constant', 'BasicObject')).
         to be_a BasicObject
     end
+    it 'returns symbol' do
+      expect(Kansen::Mapper::NoteParser.parse('symbol', 'foo')).
+        to be_a Symbol
+    end
   end
 end

spec/unit/kansen/mapper/note_type_spec.rb

@@ -11,7 +11,7 @@
 
     context 'when valid type' do
       %w{
-        string integer float constant
+        string integer float constant symbol
       }.each do |type|
         it "returns #{type} type" do
           expect(subject.perform(type)).to eq type

spec/unit/kansen/parser/symbol_spec.rb

@@ -0,0 +1,9 @@
+require 'spec_helper'
+
+describe Kansen::Parser::Integer do
+  describe '.parse' do
+    it 'converts note to integer' do
+      expect(Kansen::Parser::Symbol.parse('kansen')).to eq :kansen
+    end
+  end
+end