为什么使用JUnit在Java类中编译对fail()的调用 [英] Why does a call to fail() compile in a Java Class using JUnit

问题描述

这似乎不应该编译和运行，因为Object没有fail()方法.在编译时发生了什么时髦的事情? (我正在使用NetBeans):

This seems like it shouldn't compile and run as Object does not have a fail() method. At compile time is something funky happening? (I am using NetBeans):

import static org.junit.Assert.*;
import org.junit.Test;

public class Test {

    @Test
    public void hello() {
        fail();

    }
}

此致

Guido

推荐答案

您的import static行将Assert类的所有静态成员导入到编译单元的静态名称空间中. fail()调用引用Assert.fail().

Your import static line imports all static members of the Assert class into the static namespace of your compilation unit. The fail() call refers to Assert.fail().

您对定义fail()的位置所遇到的困惑正是为什么我通常不建议使用import static的原因.在我自己的代码中，我通常导入该类并使用它来调用静态方法:

The confusion you are experiencing regarding where fail() is defined is precisely why I don't usually recommend using import static. In my own code, I usually import the class and use it to invoke the static methods:

import org.junit.Assert;
import org.junit.Test;

public class Test {

    @Test
    public void hello() {
        Assert.fail();
    }
}

更具可读性.

但是，作为

However, as JB Nizet points out, it is fairly common practice to use import static for JUnit's assertions; when you write and read enough JUnit tests, knowing where the assertion methods come from will become second nature.

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