如何对读取给定文件的方法进行单元测试 [英] How to unit test a method that reads a given file

问题描述

我知道这有点天真。如何在不给物理文件作为输入的情况下对这段代码进行单元测试。
我是模拟和单元测试的新手。所以我不确定。请帮忙。

I know this is a bit naive. How to unit test this piece of code without giving physical file as input. I am new to mockito and unit testing. So I am not sure. Please help.

public static String fileToString(File file) throws IOException
{
    BufferedReader br = new BufferedReader(new FileReader(file));
    try {
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();

        while (line != null) {
            sb.append(line);
            sb.append("\n");
            line = br.readLine();
        }
        return sb.toString();
    } finally {
        br.close();
    }
}

推荐答案

你应该重构你的方法。如您所知，将文件作为输入的方法不容易测试。此外，它似乎是静态的，这无助于可测试性。如果您将方法重写为：

You should probably refactor your method. As you realized, a method taking a file as input isn't easily testable. Also, it seems to be static, which doesn't help testability. If you rewrite your method as :

public String fileToString(BufferedReader input) throws IOException

测试会容易得多。您将业务逻辑从读取文件的技术性中分离出来。据我了解，您的业务逻辑是读取流并确保行结尾为unix样式。

it will be much easier to test. You separate your business logic form the technicalities of reading a file. As I understand it, your business logic is reading a stream and ensuring the line endings are unix style.

如果这样做，您的方法将是可测试的。您还可以使它更通用：它现在可以从文件，URL或任何类型的流中读取。更好的代码，更容易测试......

If you do that, your method will be testable. You also make it more generic : it can now read from a file, from a URL, or from any kind of stream. Better code, easier to test ...

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