单身和单元测试 [英] Singleton and unit testing

问题描述

Effective Java在单元测试单例上有以下声明

The Effective Java has the following statement on unit testing singletons

使类成为单例可能会使其难以测试其客户端，因为除非它实现了作为其类型的接口，否则不可能将模拟实现替换为单例。

Making a class a singleton can make it difficult to test its clients, as it’s impossible to substitute a mock implementation for a singleton unless it implements an interface that serves as its type.

任何人都可以解释为什么是这样吗？

Can anyone explain the why this is so ?

推荐答案

您可以使用反射来重置单例对象，以防止测试相互影响。

You could use reflection to reset your singleton object to prevent tests from affecting each other.

@Before
public void resetSingleton() throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
   Field instance = MySingleton.class.getDeclaredField("instance");
   instance.setAccessible(true);
   instance.set(null, null);
}

参考： unit-testing-singletons

这篇关于单身和单元测试的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！