From 0cc486a9753475c5d626b9369c423af1bae47705 Mon Sep 17 00:00:00 2001
From: Ken Hibino <ken.hibino7@gmail.com>
Date: Sun, 16 Feb 2020 21:09:16 -0800
Subject: [PATCH] Fix data race in syncer test

---
 syncer_test.go | 63 +++++++++++++++++++++-----------------------------
 1 file changed, 26 insertions(+), 37 deletions(-)

diff --git a/syncer_test.go b/syncer_test.go
index 24793df..37ce92b 100644
--- a/syncer_test.go
+++ b/syncer_test.go
@@ -5,11 +5,11 @@
 package asynq
 
 import (
+	"fmt"
 	"sync"
 	"testing"
 	"time"
 
-	"github.com/go-redis/redis/v7"
 	h "github.com/hibiken/asynq/internal/asynqtest"
 	"github.com/hibiken/asynq/internal/base"
 	"github.com/hibiken/asynq/internal/rdb"
@@ -50,54 +50,43 @@ func TestSyncer(t *testing.T) {
 }
 
 func TestSyncerRetry(t *testing.T) {
-	inProgress := []*base.TaskMessage{
-		h.NewTaskMessage("send_email", nil),
-		h.NewTaskMessage("reindex", nil),
-		h.NewTaskMessage("gen_thumbnail", nil),
-	}
-	goodClient := setup(t)
-	h.SeedInProgressQueue(t, goodClient, inProgress)
-
-	// Simulate the situation where redis server is down
-	// by connecting to a wrong port.
-	badClient := redis.NewClient(&redis.Options{
-		Addr: "localhost:6390",
-	})
-	rdbClient := rdb.NewRDB(badClient)
-
 	const interval = time.Second
 	syncRequestCh := make(chan *syncRequest)
 	syncer := newSyncer(syncRequestCh, interval)
+
 	var wg sync.WaitGroup
 	syncer.start(&wg)
 	defer syncer.terminate()
 
-	for _, msg := range inProgress {
-		m := msg
-		syncRequestCh <- &syncRequest{
-			fn: func() error {
-				return rdbClient.Done(m)
-			},
+	var (
+		mu      sync.Mutex
+		counter int
+	)
+
+	// Increment the counter for each call.
+	// Initial call will fail and second call will succeed.
+	requestFunc := func() error {
+		mu.Lock()
+		defer mu.Unlock()
+		if counter == 0 {
+			counter++
+			return fmt.Errorf("zero")
 		}
+		counter++
+		return nil
 	}
 
-	time.Sleep(2 * interval) // ensure that syncer runs at least once
-
-	// Sanity check to ensure that message was not successfully deleted
-	// from in-progress list.
-	gotInProgress := h.GetInProgressMessages(t, goodClient)
-	if l := len(gotInProgress); l != len(inProgress) {
-		t.Errorf("%q has length %d; want %d", base.InProgressQueue, l, len(inProgress))
+	syncRequestCh <- &syncRequest{
+		fn:     requestFunc,
+		errMsg: "error",
 	}
 
-	// FIXME: This assignment introduces data race and running the test with -race will fail.
-	// simualate failover.
-	rdbClient = rdb.NewRDB(goodClient)
+	// allow syncer to retry
+	time.Sleep(3 * interval)
 
-	time.Sleep(2 * interval) // ensure that syncer runs at least once
-
-	gotInProgress = h.GetInProgressMessages(t, goodClient)
-	if l := len(gotInProgress); l != 0 {
-		t.Errorf("%q has length %d; want 0", base.InProgressQueue, l)
+	mu.Lock()
+	if counter != 2 {
+		t.Errorf("counter = %d, want 2", counter)
 	}
+	mu.Unlock()
 }