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Transcript from the "Jest Watch" Lesson
>> Brian: Show you one more cool feature about Jest that I like, npm run test, and if I do --, anything that I put after the -- will actually pass to Jest. So I can put -- watch, like that, and run it. And it's actually gonna run Jest in an interactive mode which I find to be fascinating.
[00:00:20] So I can just hit A, and it'll rerun all the test again for me.
>> Brian: Or I can tell to, only run some tests, right? But it'll actually be file watching all of my modules. And if I change anything inside details, it'll rerun the test because it knows that the details test pulls in the details module, right?
[00:00:41] So, let's go make it fail again. If I turn this to true. Saved it. Now, I have to go back over here and it's going to say, hey, that failed, right? You get instant feedback that that failed. And then, if I go back and change it to false again, it goes, no, I'm happy.
[00:00:56] So, it only runs the subset of tests that could have possibly failed in the interim. I don't know if any of you have enormous test feats that take minutes to run. This is a godsend for those sorts of people, right? Something else that just does that's really intelligent, it runs the last test to fail first.
[00:01:17] So it'll actually run your tests out of order, because it wants to fail as fast as possible. Which I also find to be extremely useful. So, let's go ahead and add that to our pax.json as well.
>> Brian: So, we have test update here, test : watch. This is jest -- silent -- watch, like that.
>> Brian: And now, you can just say, mpm run test : watch, and it puts you right into that mode right away.