下面是一个java函数的单元测试用例：

def "should generate claims error file"(){
    given:
    def tempFile = new TempFile()
    def excelErrorRecord = new ExcelErrorRecord(row: 5, col: 4, message: "Test Message")
    HashMap<String, List<ExcelErrorRecord>> errorRecords = new HashMap<>();
    errorRecords.put("Medical",[excelErrorRecord])
    def fileInputStream = Mock(FileInputStream)
    def workBook = Mock(Workbook)
    def file = Mock(File)

    and:
    tempFile.getFile() >> file
    file.length() >> 100
    tempFile.getFile().getAbsolutePath() >> "Temp File.xlsx"
    new FileInputStream(tempFile.getFile().getAbsolutePath()) >> fileInputStream
    new XSSFWorkbook(fileInputStream) >> workBook

    when:
    service.generateClaimsErrorFile(errorRecords, tempFile)

    then:
    noExceptionThrown()
  }

字符串
本测试用例将执行以下java函数：

try (FileInputStream fis = new FileInputStream(tempFile.getFile().getAbsolutePath());
         Workbook workbook = new XSSFWorkbook(fis)) 
{}
catch(){}

型
上面的测试用例是在Workbook workbook = new XSSFWorkbook(fis)行抛出org.apache.poi.EmptyFileException。我如何解决这个问题，这个问题的原因是什么？