adding unit test for windows storage driver

Author: Dave Try

manifests/init.pp

@@ -520,13 +520,13 @@
     if $::osfamily == 'windows' {
       assert_type(Pattern[/^(windowsfilter)$/], $storage_driver) |$a, $b| {
           fail translate(('Valid values for storage_driver on windows are windowsfilter'))
-      }      
+      }
     } else {
       assert_type(Pattern[/^(aufs|devicemapper|btrfs|overlay|overlay2|vfs|zfs)$/], $storage_driver) |$a, $b| {
         fail translate(('Valid values for storage_driver are aufs, devicemapper, btrfs, overlay, overlay2, vfs, zfs.'))
       }
     }
-  }  
+  }
 
   if ($bridge) and ($::osfamily == 'windows') {
       assert_type(Pattern[/^(none|nat|transparent|overlay|l2bridge|l2tunnel)$/], $bridge) |$a, $b| {

spec/classes/docker_windows_spec.rb

@@ -123,7 +123,27 @@
             }.to raise_error(Puppet::Error, /log_level must be one of debug, info, warn, error or fatal/)
         end
       end
+
+      context 'with storage_driver' do
+        let(:params) { {
+            'storage_driver' => 'windowsfilter',
+            'docker_ee' => true 
+        } }
+        it { should compile.with_all_deps }
+      end
 
+      context 'with an invalid storage_driver' do
+        let(:params) { {
+            'storage_driver' => 'invalid',
+            'docker_ee' => true 
+        } }
+        it do
+            expect {
+              should contain_package('docker')
+            }.to raise_error(Puppet::Error, /Valid values for storage_driver on windows are windowsfilter/)
+        end
+      end
+
       context 'with tcp_bind' do
         let(:params) { { 
             'tcp_bind'   => "tcp://0.0.0.0:2376",