Set time unit on metrics.Timer

metrics/timer_test.go

@@ -31,3 +31,29 @@ func TestTimerSlow(t *testing.T) {
 		t.Errorf("want %.3f, have %.3f", want, have)
 	}
 }
+
+func TestTimerUnit(t *testing.T) {
+
+	for _, tc := range []struct {
+		name      string
+		unit      time.Duration
+		tolerance float64
+		want      float64
+	}{
+		{"Seconds", time.Second, 0.010, 0.100},
+		{"Milliseconds", time.Millisecond, 10, 100},
+		{"Nanoseconds", time.Nanosecond, 10000000, 100000000},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			h := generic.NewSimpleHistogram()
+			timer := metrics.NewTimer(h)
+			time.Sleep(100 * time.Millisecond)
+			timer.Unit(tc.unit)
+			timer.ObserveDuration()
+
+			if want, have := tc.want, h.ApproximateMovingAverage(); math.Abs(want-have) > tc.tolerance {
+				t.Errorf("want %.3f, have %.3f", want, have)
+			}
+		})
+	}
+}