Merge pull request #22 from puppetlabs/tasks/add-noop-instrumentation…

…-delegate

Update: Add noop metrics delegate for testing

instrumentation/metrics/delegates/delegates.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 
 	"github.com/puppetlabs/horsehead/v2/instrumentation/metrics/collectors"
+	"github.com/puppetlabs/horsehead/v2/instrumentation/metrics/internal/noop"
 	"github.com/puppetlabs/horsehead/v2/instrumentation/metrics/internal/prometheus"
 )
 
@@ -22,13 +23,16 @@ type DelegateType string
 const (
 	// PrometheusDelegate is a const that represents the prometheus backend
 	PrometheusDelegate DelegateType = "prometheus"
+	NoopDelegate       DelegateType = "noop"
 )
 
 // New looks up t and returns a new Delegate matching that type
 func New(namespace string, t DelegateType) (Delegate, error) {
 	switch t {
 	case PrometheusDelegate:
 		return prometheus.New(namespace), nil
+	case NoopDelegate:
+		return noop.New(), nil
 	}
 
 	return nil, errors.New("no delegate found")

instrumentation/metrics/internal/noop/noop.go

@@ -0,0 +1,29 @@
+package noop
+
+import (
+	"net/http"
+
+	"github.com/puppetlabs/horsehead/v2/instrumentation/metrics/collectors"
+)
+
+type Noop struct{}
+
+func (n *Noop) NewCounter(name string, opts collectors.CounterOptions) (collectors.Counter, error) {
+	return &Counter{}, nil
+}
+
+func (n *Noop) NewTimer(name string, opts collectors.TimerOptions) (collectors.Timer, error) {
+	return &Timer{}, nil
+}
+
+func (n *Noop) NewDurationMiddleware(name string, opts collectors.DurationMiddlewareOptions) (collectors.DurationMiddleware, error) {
+	return &DurationMiddleware{}, nil
+}
+
+func (n *Noop) NewHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {})
+}
+
+func New() *Noop {
+	return &Noop{}
+}