Today I was in a piano discussion for test JS Summit and a question was

asked about like what's the use case for unit tests if we focus onintegration and component level tests. And I talked about this and and itwas kind of more about like what what's the shape of our testing trophy ortesting pyramid or whatever like where do we focus our tests?

And I talk about how I recommend that you focus on integration and

component-type tests and try to mock as little as possible. I typicallydon't mock modules all that often and most often will just.Mock HTTPrequests unless we're doing end tests in which case you mock nothing. Andthe the way that I think about it is like if you just have 100% unit testsand that's all that you're writing and you get a hundred percent codecoverage with that you're still very likely to have lots of bugs creep upas integrations between different pieces of these units change.

And that can be very difficult to track when you are just mocking all the

modules and just unit unit testing everything. And so you're gonna startmoving over to component or integration.And type tests and with that youend up realizing that you don't need those unit tests as much becausethey're covered by the integration test and so okay now we just don'tbother writing those and we just focus on integration tests but event atsome point if you just say, oh let's just do all integration tests you'regonna find that it's a lot very repetitive to cover certain cases.

Maybe you have some functions that are doing some computations in there a

lot of different parts of the algorithm that you're using or whatever, youknow, tons of branches if statements turn areas all over the place that youhave to cover.To you know feel confident that you can ship this code And sothose are the types of things that I actually move over to unit testing.

And so we'll have a single integration task that's or maybe a handful of

integration tests that are testing the more common use cases, but thenyou'd have a unit test for the specific unit of code that is more complex.It's typically these are going to be pure functions but not always butthey'll often be pure functions that you just call it with some arguments.

You get some result back. And these types of tests run really fast and

they're really quite easy to run.And maintain and so that's kind of where Isee unit tests fit into the spectrum of what types of tests that you write.I've written about this on my blog.

If you go to https://kcd.im/trophy, you'll find it it's a static versus

unit versus integration versus end testing. A kind of lays out thedifferences there. Anyway, I hope that's helpful to you have a wonderfulawesome day and we'll chat with you later.