控制台输入和输出的 JUnit 测试 [英] JUnit test for console input and output

问题描述

我只有一个方法 main.如何检查 System.out.println() 并将 Scanner 替换为使用 JUnit 自动输入值?

I have only one method main. How to check System.out.println() and replace Scanner to input values automatically using JUnit?

附言请提供一些解决方案...

P.S. Please, provide some solutions...

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int[] arr = new int[4];

    for (int i = 0; i < arr.length; i++) {
        arr[i] = scanner.nextInt();
    }

    for (int i = 0; i < arr.length; i++) {
        int res = 0;
        int k = 0;
        int num = arr[i];
        /*.....*/
        System.out.println(num);
    }
}

推荐答案

理想情况下，提取笨拙的依赖项，以便您可以在没有它们的情况下进行测试.将 main 更改为简单的:

Ideally, extract the awkward dependencies so that you can test without them. Change main to simply:

public static void main(String[] args) {
  doWork(new Scanner(System.in), System.out);
}

// TODO: Rename to something meaningful
public static void doWork(Scanner input, PrintStream output) {
  // Remainder of code
}

(考虑对 output 使用 Writer 而不是 PrintStream.)

(Consider using a Writer instead of a PrintStream for output.)

然后你真的不需要单元测试 main - 但是你可以使用基于 的 Scanner 测试 doWorkStringReader，以及基于 StringWriter 的输出，提供您想要的任何输入并检查输出.

Then you don't really need to unit test main - but you can test doWork using a Scanner based on a StringReader, and output based on a StringWriter, providing whatever input you want and checking the output.

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