scala - 最终在 Specs2 上尝试编写带有闭包的测试失败

Question

我正在尝试使用 Specs2 编写以下规范，但似乎无法使其正常工作，编译器总是提示“Unit => org.specs2.execute.Result 中没有可用的隐式 View ”。

这是测试源:

    "generate the correct output when merging an extraction" in {
        val source = new File("src/test/resources/sample-docs/text-and-image-on-page-2.pdf")
        val output = this.extractor.extract(source)
        val pdfGenerator = new ITextPdfGenerator()
        val processor = new ExecutableProcessor()

        val ocrInput = IOUtils.createTempFile("ocr_input", "pdf")
        val ocrOutput = IOUtils.createTempFile("ocr_output", "pdf")

        deleteWhenDone[MatchResult[Any]](output.getFullTextFile, ocrInput, ocrOutput) ( {

            pdfGenerator.generatePdf(source, ocrInput, output.getPagesWithImages)
            processor.process(ocrInput, ocrOutput)

            this.extractor.mergeExtraction(output, ocrOutput)

            IOUtils.readFile(output.getFullTextFile) === """sample text on line 1 page 1 sample text on line 2 page 1 sample text on line 1 page 3 sample text on line 2 page 3 """

        })

    }

完成后删除功能如下:

def deleteWhenDone[T]( files : File* ) ( fn : => T ) {
    try {
        fn
    } finally {
        IOUtils.deleteFiles( files )
    }
}

如果这一行在规范的末尾，它确实有效:

IOUtils.readFile(output.getFullTextFile) === "sample text on line 1 page 1 sample text on line 2 page 1 sample text on line 1 page 3 sample text on line 2 page 3 "

为什么它会像这样失败，我该怎么做才能继续使用闭包并让测试通过编译？

编辑

将 deleteWhenDone 调用更改为此:

deleteWhenDone[Result](output.getFullTextFile, ocrInput, ocrOutput) ( {

  pdfGenerator.generatePdf(source, ocrInput, output.getPagesWithImages)
  processor.process(ocrInput, ocrOutput)

  this.extractor.mergeExtraction(output, ocrOutput)

  IOUtils.readFile(output.getFullTextFile) === "sample text on line 1 page 1 sample text on line 2 page 1 sample text on line 1 page 3 sample text on line 2 page 3 "

})

但还是不行。

编辑 2

感谢 Rafael 的回答，使它工作的最终代码是:

def deleteWhenDone[T]( files : File* ) ( fn : => T ) : T = {
    try {
        fn
    } finally {
        IOUtils.deleteFiles( files )
    }
}

我错过了方法返回类型。谢谢!

Answer 1

deleteWhenDone 函数的结果类型为 Unit，这与 in 参数的预期类型不兼容。您可以通过在定义中添加等号将其更改为返回 T:

def deleteWhenDone[T]( files : File* ) ( fn : => T ) = {
    try {
        fn
    } finally {
        IOUtils.deleteFiles( files )
    }
}