java - Java , tdd 方法, IO 操作

Question

我正在训练 TDD 方法，但我有一个问题。如何测试 IO 操作？到目前为止，我使用的是 junit，但我读到它不应该用于测试外部源（数据库、文件......），那么什么会更好？对不起，我的英语不好

Answer 1

You can't test the internal working of those external sources, but you can check the results.

For example, writing to a file:

Start test
Store data you want to write in a variable
Write data to file
Read file
Check if data is the same as the one you stored
End test

Testing is about verifying end results, so it's not necessarily a bad thing you "lose" sight of a part of the process. Generally you can assume external sources (libraries, IO..) are well tested.

Answer 2

更改要传递的 APIInputStream和/或OutputStream让 jUnit 代码传递 ByteArrayInputStream 和ByteArrayOutputStream，您可以轻松地设置/读取它们。

当然，您的生产代码需要更改为，但您通常可以通过简单的重构来实现；保留 API 原样，但让公共方法调用重构的方法，例如：

改变

public void read(File file) {
    // do something with contents of file
}

至

public void read(File file) {
    read(new FileInputStream(file));
}

// test this method
public void read(InputStream inputStream) {
    // do something with contents of inputStream
}