Add test case to ensure graceful failure on OSX.

spec/classes/init_spec.rb

@@ -54,4 +54,16 @@ describe 'apt' do
     it { should contain_file('puppetlabs.list').with_content(/^deb http:\/\/apt.puppetlabs.com precise main$/) }
     it { should contain_file('puppetlabs.list').with_content(/^deb-src http:\/\/apt.puppetlabs.com precise main$/) }
   end
+
+  context 'with unsupported osfamily' do
+    let :facts do
+      { :osfamily        => 'Darwin', }
+    end
+
+    it do
+      expect {
+       should compile
+      }.to raise_error(Puppet::Error, /This module only works on Debian or derivatives like Ubuntu/)
+    end
+  end
 end