Extract metrics to own package and refactor implementations

metrics/metrics_test.go

@@ -0,0 +1,87 @@
+package metrics
+
+import (
+	"testing"
+
+	"github.com/go-kit/kit/metrics"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewVoidRegistry(t *testing.T) {
+	registry := NewVoidRegistry()
+
+	if registry.IsEnabled() {
+		t.Errorf("VoidRegistry should not return true for IsEnabled()")
+	}
+	registry.ReqsCounter().With("some", "value").Add(1)
+	registry.ReqDurationHistogram().With("some", "value").Observe(1)
+	registry.RetriesCounter().With("some", "value").Add(1)
+}
+
+func TestNewMultiRegistry(t *testing.T) {
+	registries := []Registry{newCollectingRetryMetrics(), newCollectingRetryMetrics()}
+	registry := NewMultiRegistry(registries)
+
+	registry.ReqsCounter().With("key", "requests").Add(1)
+	registry.ReqDurationHistogram().With("key", "durations").Observe(2)
+	registry.RetriesCounter().With("key", "retries").Add(3)
+
+	for _, collectingRegistry := range registries {
+		cReqsCounter := collectingRegistry.ReqsCounter().(*counterMock)
+		cReqDurationHistogram := collectingRegistry.ReqDurationHistogram().(*histogramMock)
+		cRetriesCounter := collectingRegistry.RetriesCounter().(*counterMock)
+
+		wantCounterValue := float64(1)
+		if cReqsCounter.counterValue != wantCounterValue {
+			t.Errorf("Got value %f for ReqsCounter, want %f", cReqsCounter.counterValue, wantCounterValue)
+		}
+		wantHistogramValue := float64(2)
+		if cReqDurationHistogram.lastHistogramValue != wantHistogramValue {
+			t.Errorf("Got last observation %f for ReqDurationHistogram, want %f", cReqDurationHistogram.lastHistogramValue, wantHistogramValue)
+		}
+		wantCounterValue = float64(3)
+		if cRetriesCounter.counterValue != wantCounterValue {
+			t.Errorf("Got value %f for RetriesCounter, want %f", cRetriesCounter.counterValue, wantCounterValue)
+		}
+
+		assert.Equal(t, []string{"key", "requests"}, cReqsCounter.lastLabelValues)
+		assert.Equal(t, []string{"key", "durations"}, cReqDurationHistogram.lastLabelValues)
+		assert.Equal(t, []string{"key", "retries"}, cRetriesCounter.lastLabelValues)
+	}
+}
+
+func newCollectingRetryMetrics() Registry {
+	return &standardRegistry{
+		reqsCounter:          &counterMock{},
+		reqDurationHistogram: &histogramMock{},
+		retriesCounter:       &counterMock{},
+	}
+}
+
+type counterMock struct {
+	counterValue    float64
+	lastLabelValues []string
+}
+
+func (c *counterMock) With(labelValues ...string) metrics.Counter {
+	c.lastLabelValues = labelValues
+	return c
+}
+
+func (c *counterMock) Add(delta float64) {
+	c.counterValue += delta
+}
+
+type histogramMock struct {
+	lastHistogramValue float64
+	lastLabelValues    []string
+}
+
+func (c *histogramMock) With(labelValues ...string) metrics.Histogram {
+	c.lastLabelValues = labelValues
+	return c
+}
+
+func (c *histogramMock) Observe(value float64) {
+	c.lastHistogramValue = value
+}