From 0bf16f704d699b9b257c37760e756ea88753fc5e Mon Sep 17 00:00:00 2001
From: Haytham AbuelFutuh <habuelfutuh@lyft.com>
Date: Fri, 12 Jul 2019 13:41:04 -0700
Subject: [PATCH] WIP

---
 utils/auto_refresh_cache_test.go | 39 ++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/utils/auto_refresh_cache_test.go b/utils/auto_refresh_cache_test.go
index 53b5167..598774f 100644
--- a/utils/auto_refresh_cache_test.go
+++ b/utils/auto_refresh_cache_test.go
@@ -3,6 +3,8 @@ package utils
 import (
 	"context"
 	"fmt"
+	"math"
+	rand2 "math/rand"
 	"strconv"
 	"sync"
 	"testing"
@@ -40,12 +42,45 @@ func noopSync(_ context.Context, obj CacheItem) (CacheItem, CacheSyncAction, err
 	return obj, Unchanged, nil
 }
 
+func sometimesUpdateOnSync(percentage float32) CacheSyncItem {
+	r := rand2.New(rand2.NewSource(time.Now().Unix()))
+	p := int(percentage * 100)
+	return func(_ context.Context, obj CacheItem) (CacheItem, CacheSyncAction, error) {
+		if r.Int()%100 < p {
+			return obj, Update, nil
+		}
+
+		return obj, Unchanged, nil
+	}
+}
+
+func TestSometimesUpdateOnSync(t *testing.T) {
+	for expected := 1.0; expected <= 10; expected++ {
+		perc := float32(expected / 100.0)
+		f := sometimesUpdateOnSync(perc)
+		updateCount := 0
+		for i := 0; i < 10000; i++ {
+			for j := 0; j < 100; j++ {
+				_, action, err := f(nil, nil)
+				assert.NoError(t, err)
+				if action == Update {
+					updateCount++
+				}
+			}
+		}
+
+		actual := float64(updateCount / 10000.0)
+		assert.True(t, expected <= math.Ceil(actual)+1 && expected >= math.Floor(actual)-1,
+			"Expected: %v, Actual: %v", expected, actual)
+	}
+}
+
 func BenchmarkCache(b *testing.B) {
-	testResyncPeriod := time.Millisecond
+	testResyncPeriod := time.Second
 	rateLimiter := NewRateLimiter("mockLimiter", 100, 1)
 	// the size of the cache is at least as large as the number of items we're storing
 	itemCount := b.N
-	cache, err := NewAutoRefreshCache(noopSync, rateLimiter, testResyncPeriod, itemCount*2, nil)
+	cache, err := NewAutoRefreshCache(sometimesUpdateOnSync(1), rateLimiter, testResyncPeriod, itemCount*2, nil)
 	assert.NoError(b, err)
 
 	ctx, cancel := context.WithCancel(context.Background())