* Define missing InvalidLogin exception

* Add login tests

lib/fog/xenserver.rb

@@ -1,5 +1,8 @@
 module Fog
   module XenServer 
+
+    class InvalidLogin < Fog::Errors::Error; end
+
     extend Fog::Provider
     
     service(:compute, 'xenserver/compute', 'Compute')  
@@ -13,10 +16,8 @@ module Fog
       end
     
       def authenticate( username, password )
-        begin
+        response = @factory.call('session.login_with_password', username, password )
-          response = @factory.call('session.login_with_password', username, password )
+        raise Fog::XenServer::InvalidLogin.new unless response["Status"] =~ /Success/
-          raise Fog::XenServer::InvalidLogin unless response["Status"] =~ /Success/
-        end
         @credentials = response["Value"]
       end
     

tests/xenserver/xenserver_tests.rb

@@ -0,0 +1,34 @@
+Shindo.tests('Fog::Compute[:xenserver]', ['xenserver']) do
+
+  tests("Login") do
+    raises(Fog::XenServer::InvalidLogin, 'raises error when invalid password') do
+      conn = Fog::Compute.new({
+        :provider => 'XenServer',
+        :xenserver_url => 'xenserver-test',
+        :xenserver_username => 'root',
+        :xenserver_password => 'asdfsadf'
+
+      })
+    end
+    raises(Fog::XenServer::InvalidLogin, 'raises error when invalid user') do
+      conn = Fog::Compute.new({
+        :provider => 'XenServer',
+        :xenserver_url => 'xenserver-test',
+        :xenserver_username => 'rootffff',
+        :xenserver_password => 'changeme'
+
+      })
+    end
+    raises(SocketError, 'raises error when invalid host') do
+      conn = Fog::Compute.new({
+        :provider => 'XenServer',
+        :xenserver_url => 'xenserver-testlakjsdflkj',
+        :xenserver_username => 'root',
+        :xenserver_password => 'changeme'
+
+      })
+    end
+  end
+
+end
+