add metrics for backend_retries_total

middlewares/metrics_test.go

@@ -0,0 +1,48 @@
+package middlewares
+
+import (
+	"testing"
+
+	"github.com/go-kit/kit/metrics"
+)
+
+func TestMetricsRetryListener(t *testing.T) {
+	// nil implementation, nothing should fail
+	retryListener := NewMetricsRetryListener(nil)
+	retryListener.Retried(1)
+
+	retryMetrics := newCollectingMetrics()
+	retryListener = NewMetricsRetryListener(retryMetrics)
+	retryListener.Retried(1)
+	retryListener.Retried(2)
+
+	wantCounterValue := float64(2)
+	if retryMetrics.retryCounter.counterValue != wantCounterValue {
+		t.Errorf("got counter value of %d, want %d", retryMetrics.retryCounter.counterValue, wantCounterValue)
+	}
+}
+
+// collectingRetryMetrics is an implementation of the RetryMetrics interface that can be used inside tests to collect the times Add() was called.
+type collectingRetryMetrics struct {
+	retryCounter *collectingCounter
+}
+
+func newCollectingMetrics() collectingRetryMetrics {
+	return collectingRetryMetrics{retryCounter: &collectingCounter{}}
+}
+
+func (metrics collectingRetryMetrics) getRetryCounter() metrics.Counter {
+	return metrics.retryCounter
+}
+
+type collectingCounter struct {
+	counterValue float64
+}
+
+func (c *collectingCounter) With(labelValues ...string) metrics.Counter {
+	panic("collectingCounter.With not implemented!")
+}
+
+func (c *collectingCounter) Add(delta float64) {
+	c.counterValue += delta
+}