在npm init中，grunt“测试命令”做什么

I'm trying to learn grunt. When I run npm init, I get a prompt in the process of creating a package.json file that asks for "test command" - I'm not sure how to utilize this, or what it's expecting. It doesn't seem to be well documented. If I leave it blank, I get this in the resulting package.json file:I'm trying to learn grunt. When I run npm init,