add noop broker and noop store (#30)

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

broker/broker.go

@@ -2,7 +2,7 @@
 package broker
 
 var (
-	DefaultBroker Broker
+	DefaultBroker Broker = newBroker()
 )
 
 // Broker is an interface used for asynchronous messaging.

broker/noop.go

@@ -0,0 +1,74 @@
+package broker
+
+type noopBroker struct {
+	opts Options
+}
+
+type noopSubscriber struct {
+	topic string
+	opts  SubscribeOptions
+}
+
+func (n *noopBroker) Init(opts ...Option) error {
+	for _, o := range opts {
+		o(&n.opts)
+	}
+
+	return nil
+}
+
+func (n *noopBroker) Options() Options {
+	return n.opts
+}
+
+func (n *noopBroker) Address() string {
+	return ""
+}
+
+func (n *noopBroker) Connect() error {
+	return nil
+}
+
+func (n *noopBroker) Disconnect() error {
+	return nil
+}
+
+func (n *noopBroker) Publish(topic string, m *Message, opts ...PublishOption) error {
+	return nil
+}
+
+func (n *noopBroker) Subscribe(topic string, h Handler, opts ...SubscribeOption) (Subscriber, error) {
+	options := NewSubscribeOptions()
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return &noopSubscriber{topic: topic, opts: options}, nil
+}
+
+func (n *noopBroker) String() string {
+	return "noop"
+}
+
+func (n *noopSubscriber) Options() SubscribeOptions {
+	return n.opts
+}
+
+func (n *noopSubscriber) Topic() string {
+	return n.topic
+}
+
+func (n *noopSubscriber) Unsubscribe() error {
+	return nil
+}
+
+// newBroker returns a new noop broker
+func newBroker(opts ...Option) Broker {
+	options := NewOptions()
+
+	for _, o := range opts {
+		o(&options)
+	}
+	return &noopBroker{opts: options}
+}