add opentracing spans for metrics

vendor/github.com/rcrowley/go-metrics/meter_test.go

@@ -0,0 +1,60 @@
+package metrics
+
+import (
+	"testing"
+	"time"
+)
+
+func BenchmarkMeter(b *testing.B) {
+	m := NewMeter()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Mark(1)
+	}
+}
+
+func TestGetOrRegisterMeter(t *testing.T) {
+	r := NewRegistry()
+	NewRegisteredMeter("foo", r).Mark(47)
+	if m := GetOrRegisterMeter("foo", r); 47 != m.Count() {
+		t.Fatal(m)
+	}
+}
+
+func TestMeterDecay(t *testing.T) {
+	ma := meterArbiter{
+		ticker: time.NewTicker(time.Millisecond),
+	}
+	m := newStandardMeter()
+	ma.meters = append(ma.meters, m)
+	go ma.tick()
+	m.Mark(1)
+	rateMean := m.RateMean()
+	time.Sleep(100 * time.Millisecond)
+	if m.RateMean() >= rateMean {
+		t.Error("m.RateMean() didn't decrease")
+	}
+}
+
+func TestMeterNonzero(t *testing.T) {
+	m := NewMeter()
+	m.Mark(3)
+	if count := m.Count(); 3 != count {
+		t.Errorf("m.Count(): 3 != %v\n", count)
+	}
+}
+
+func TestMeterSnapshot(t *testing.T) {
+	m := NewMeter()
+	m.Mark(1)
+	if snapshot := m.Snapshot(); m.RateMean() != snapshot.RateMean() {
+		t.Fatal(snapshot)
+	}
+}
+
+func TestMeterZero(t *testing.T) {
+	m := NewMeter()
+	if count := m.Count(); 0 != count {
+		t.Errorf("m.Count(): 0 != %v\n", count)
+	}
+}