make tests not overwrite non-mutable document 'id'

spec/license_meta_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe 'license meta' do
   licenses.each do |license|
     # Manually load the raw license so we don't get the defaults
-    raw_fields = SafeYAML.load_file("_licenses/#{license['id']}.txt")
+    raw_fields = SafeYAML.load_file("_licenses/#{license['spdx-lcase']}.txt")
 
     context "The #{license['title']} license" do
       it 'should only contain supported meta fields' do

spec/license_spec.rb

@@ -7,7 +7,7 @@ describe 'licenses' do
 
   licenses.each do |license|
     context "The #{license['title']} license" do
-      let(:id) { license['id'] }
+      let(:id) { license['spdx-lcase'] }
       let(:spdx_id) { license['spdx-id'] }
 
       it 'has an SPDX ID' do

spec/spec_helper.rb

@@ -35,7 +35,7 @@ def licenses
   SpecHelper.licenses ||= begin
     site.collections['licenses'].docs.map do |license|
       id = File.basename(license.basename, '.txt')
-      license.to_liquid.merge('id' => id)
+      license.to_liquid.merge('spdx-lcase' => id)
     end
   end
 end