if len(items) != 1 {
		t.Fatalf("Expected length of the batch items to be 1 but got %v", len(items))
	}
	if len(keys) != 1 {
		t.Fatalf("Expected length of the batch keys to be 1 but got %v", len(items))
	}
	// try adding again after Get.
	for i := 0; i < int(limit); i++ {
		if err := batch.Add(i, i); err != nil {
			t.Fatalf("failed to add item %v to batch after Get; %v", i, err)
		}
		if _, ok := batch.GetByKey(i); !ok {