Make logout use a connection and not node

Authenticable methods now run on a connection not on a node, so logout must write
directly to the socket

lib/moped/authenticatable.rb

@@ -61,7 +61,7 @@ def credentials
     def login(database, username, password)
       getnonce = Protocol::Command.new(database, getnonce: 1)
       self.write([getnonce])
-      reply = self.receive_replies([getnonce]).first#.first.documents.first
+      reply = self.receive_replies([getnonce]).first
       if getnonce.failure?(reply)
         return
       end
@@ -87,7 +87,11 @@ def login(database, username, password)
     # @since 2.0.0
     def logout(database)
       command = Protocol::Command.new(database, logout: 1)
-      Operation::Read.new(command).execute(self)
+      self.write([command])
+      reply = self.receive_replies([command]).first
+      if command.failure?(reply)
+        return
+      end
       credentials.delete(database)
     end
   end

spec/moped/cluster_spec.rb

@@ -419,46 +419,63 @@
 
 describe Moped::Cluster, "authentication", mongohq: :auth do
 
-  let(:session) do
-    Support::MongoHQ.auth_session(false)
-  end
+  shared_examples_for "authenticable session" do
 
-  describe "logging in with valid credentials" do
+    context "when logging in with valid credentials" do
 
-    it "logs in and processes commands" do
-      session.login(*Support::MongoHQ.auth_credentials)
-      session.command(ping: 1).should eq("ok" => 1)
+      it "logs in and processes commands" do
+        session.login(*Support::MongoHQ.auth_credentials)
+        session.command(ping: 1).should eq("ok" => 1)
+      end
     end
-  end
 
-  describe "logging in with invalid credentials" do
+    context "when logging in with invalid credentials" do
 
-    it "raises an AuthenticationFailure exception" do
-      session.login "invalid-user", "invalid-password"
+      it "raises an AuthenticationFailure exception" do
+        session.login "invalid-user", "invalid-password"
 
-      lambda do
-        session.command(ping: 1)
-      end.should raise_exception(Moped::Errors::AuthenticationFailure)
+        lambda do
+          session.command(ping: 1)
+        end.should raise_exception(Moped::Errors::AuthenticationFailure)
+      end
+    end
+
+    context "when logging in with valid credentials and then logging out" do
+
+      before do
+        session.login(*Support::MongoHQ.auth_credentials)
+        session.command(ping: 1).should eq("ok" => 1)
+      end
+
+      it "logs out" do
+        lambda do
+          session.command dbStats: 1
+        end.should_not raise_exception
+
+        session.logout
+
+        lambda do
+          session.command dbStats: 1
+        end.should raise_exception(Moped::Errors::OperationFailure)
+      end
     end
   end
 
-  describe "logging in with valid credentials and then logging out" do
+  context "when there are multiple connections on the pool" do
 
-    before do
-      session.login(*Support::MongoHQ.auth_credentials)
-      session.command(ping: 1).should eq("ok" => 1)
+    let(:session) do
+      Support::MongoHQ.auth_session(false)
     end
 
-    it "logs out" do
-      lambda do
-        session.command dbStats: 1
-      end.should_not raise_exception
+    it_behaves_like "authenticable session"
+  end
 
-      session.logout
+  context "when there is one connections on the pool" do
 
-      lambda do
-        session.command dbStats: 1
-      end.should raise_exception(Moped::Errors::OperationFailure)
+    let(:session) do
+      Support::MongoHQ.auth_session(false, pool_size: 1)
     end
+
+    it_behaves_like "authenticable session"
   end
 end

spec/support/mongohq.rb

@@ -40,8 +40,9 @@ def auth_database
       ENV["MONGOHQ_SINGLE_NAME"]
     end
 
-    def auth_session(auth = true)
-      session = Moped::Session.new auth_seeds, database: auth_database
+    def auth_session(auth = true, options = {})
+      options.merge!(database: auth_database)
+      session = Moped::Session.new(auth_seeds, options)
       session.login(*auth_credentials) if auth
       session
     end