registry: add noop registry

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

registry/noop.go

@@ -0,0 +1,44 @@
+package registry
+
+import (
+	"errors"
+)
+
+type noopRegistry struct{}
+
+func (n *noopRegistry) Init(...Option) error {
+	return nil
+}
+
+func (n *noopRegistry) Options() Options {
+	return Options{}
+}
+
+func (n *noopRegistry) Register(*Service, ...RegisterOption) error {
+	return nil
+}
+
+func (n *noopRegistry) Deregister(*Service, ...DeregisterOption) error {
+	return nil
+}
+
+func (n *noopRegistry) GetService(string, ...GetOption) ([]*Service, error) {
+	return []*Service{}, nil
+}
+
+func (n *noopRegistry) ListServices(...ListOption) ([]*Service, error) {
+	return []*Service{}, nil
+}
+
+func (n *noopRegistry) Watch(...WatchOption) (Watcher, error) {
+	return nil, errors.New("not implemented")
+}
+
+func (n *noopRegistry) String() string {
+	return "noop"
+}
+
+// NewRegistry returns a new noop registry
+func NewRegistry(...Option) Registry {
+	return &noopRegistry{}
+}