package traceimpact

import (
	"context"
	"encoding/json"
	"strings"
	"testing"
)

func TestListMethodsReturnEmptySlicesNotNil(t *testing.T) {
	svc := NewService(nil)
	ctx := context.Background()

	items, err := svc.ListItems(ctx, 42)
	if err != nil || items == nil {
		t.Fatalf("ListItems items=%v err=%v", items, err)
	}
	index, err := svc.ListIndex(ctx, 42)
	if err != nil || index == nil {
		t.Fatalf("ListIndex index=%v err=%v", index, err)
	}
	marks, err := svc.ListOpenMarks(ctx, 42, "")
	if err != nil || marks == nil {
		t.Fatalf("ListOpenMarks marks=%v err=%v", marks, err)
	}

	raw, err := json.Marshal(map[string]any{
		"items":         items,
		"index":         index,
		"recheck_marks": marks,
	})
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(raw), "null") {
		t.Fatalf("empty lists encoded as JSON null: %s", raw)
	}
}