integration: test inflight range requests while defragmenting

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

integration/v3_maintenance_test.go

@@ -47,3 +47,31 @@ func TestV3MaintenanceHashInflight(t *testing.T) {
 
 	<-donec
 }
+
+// TestV3MaintenanceDefragmentInflightRange ensures inflight range requests
+// does not panic the mvcc backend while defragment is running.
+func TestV3MaintenanceDefragmentInflightRange(t *testing.T) {
+	defer testutil.AfterTest(t)
+	clus := NewClusterV3(t, &ClusterConfig{Size: 1})
+	defer clus.Terminate(t)
+
+	cli := clus.RandClient()
+	kvc := toGRPC(cli).KV
+	if _, err := kvc.Put(context.Background(), &pb.PutRequest{Key: []byte("foo"), Value: []byte("bar")}); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+
+	donec := make(chan struct{})
+	go func() {
+		defer close(donec)
+		kvc.Range(ctx, &pb.RangeRequest{Key: []byte("foo")})
+	}()
+
+	mvc := toGRPC(cli).Maintenance
+	mvc.Defragment(context.Background(), &pb.DefragmentRequest{})
+	cancel()
+
+	<-donec
+}