From 4cdad2ce7c6cc23933068f22b934ea4e4cb02a73 Mon Sep 17 00:00:00 2001
From: mihasya <m@mihasya.com>
Date: Fri, 6 Apr 2018 11:00:40 -0700
Subject: [PATCH] add race test for EWMA

---
 ewma_test.go | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/ewma_test.go b/ewma_test.go
index 6cadd5d..058ae2d 100644
--- a/ewma_test.go
+++ b/ewma_test.go
@@ -1,6 +1,11 @@
 package metrics
 
-import "testing"
+import (
+	"math/rand"
+	"sync"
+	"testing"
+	"time"
+)
 
 func BenchmarkEWMA(b *testing.B) {
 	a := NewEWMA1()
@@ -23,6 +28,22 @@ func BenchmarkEWMAParallel(b *testing.B) {
 	})
 }
 
+// exercise race detector
+func TestEWMAConcurrency(t *testing.T) {
+	rand.Seed(time.Now().Unix())
+	a := NewEWMA1()
+	wg := &sync.WaitGroup{}
+	reps := 100
+	for i := 0; i < reps; i++ {
+		wg.Add(1)
+		go func(ewma EWMA, wg *sync.WaitGroup) {
+			a.Update(rand.Int63())
+			wg.Done()
+		}(a, wg)
+	}
+	wg.Wait()
+}
+
 func TestEWMA1(t *testing.T) {
 	a := NewEWMA1()
 	a.Update(3)