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27. Higher order assertions

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00:00
Okay, so before we move on to our feature tests, let's have a look at pests higher order Expectations now we've already come across higher order tests where we can do something like this it
00:13
does something and we can just chain on things like posting through and Then going ahead and asserting that things were okay That's a great way to write tests, but we can do the same thing without expectations Let's have a look at how this works
00:30
By just coming up to a test like this and see what we can do to make this a little bit clearer Traditionally within PHP unit or Laravel's testing framework. We would have to do these separately So we'd have to expect the accepted friends of mine to have a count of one and the same for this as well We'd have to pluck this out and then check that it contains that friend. Let's rewrite this to use a higher order
00:55
Expectation so we're gonna go ahead and still use expect We're gonna pass in the thing that we're checking But remember we're doing multiple checks or multiple expectations and assertions on this. So we're gonna say to have count One that's pretty much exactly what we wrote here. So there's no difference here
01:15
The only difference is I've pulled this down to a new line. But now what we're gonna do is say pluck ID and then we're gonna say to contain friend ID So we could pull that up a little bit just because it makes a little bit more sense to have this in line because this
01:37
plucking relates to this particular to contain Expectation, but that's pretty much what we can do We can now get rid of these two things here and that tends to read a little bit better It's just rerun our test and sure enough it still passes and this is completely valid now if we just scroll down we don't
01:57
Really have anything that uses the same thing. Technically we have to have the same thing passing to expect So if for example, we were doing something else on user friends, we could just pass that in for now, though We don't have anything that uses the same data that we want to run these expectations on that's absolutely fine But we could do for example
02:19
To be instance of Collection if we wanted to so let's go ahead and make sure we pull the Laravel collection in and There we go. That works if you wanted to do something like that, but basically with higher-order expectations
02:37
We can just continue to chain on what we want to do instead of having to redefine Expect every single time I'll leave this in here just for reference in the downloadable source code But hopefully that makes sense now. So when you are writing things like this Just chain them on much like we saw with higher-order tests

Episode summary

In this episode, we take a closer look at higher order assertions in Pest. Remember how we've used higher order tests already to make things cleaner and more readable? Well, Pest gives us a similar pattern for our assertions, letting us chain them together neatly instead of repeating ourselves.

We start by looking at a typical assertion you'd write in PHPUnit or Laravel's testing framework—where you'd have to break things apart and check each condition separately (like checking the count, then checking if a collection contains a value). Then, we rewrite these using higher order expectations in Pest. This means we can use expect() once and chain as many assertions as we want, such as toHaveCount(1) and then pluck('id')->toContain($friendId). Not only does this make our code cleaner, but it's also way easier to read.

You'll also see some handy extras, like checking if something is an instance of a Collection, all in the same neat chain. Plus, by the end, you'll see how higher order expectations help you avoid repeating expect() calls and keep your tests tidy. Feel free to check out the sample code in the course for reference!

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