package excel

import (
	"bytes"
	"testing"
)

type row struct {
	ID   int
	Name string
}

func TestExportToWriterResetsFile(t *testing.T) {
	ex := NewExcel()
	cols := []ExportColumn{
		{Header: "ID", Field: "ID"},
		{Header: "Name", Field: "Name"},
	}
	data := []row{{ID: 1, Name: "a"}, {ID: 2, Name: "b"}}

	var buf1, buf2 bytes.Buffer
	if err := ex.ExportToWriter(&buf1, "S1", cols, data); err != nil {
		t.Fatal(err)
	}
	if err := ex.ExportToWriter(&buf2, "S1", cols, data); err != nil {
		t.Fatal(err)
	}
	if buf1.Len() == 0 || buf2.Len() == 0 {
		t.Fatal("expected non-empty xlsx output")
	}
	// 导出后不应残留内部文件句柄
	if ex.file != nil {
		t.Fatal("internal file should be cleared after ExportToWriter")
	}
}