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06.

Testing a Service

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If you click this button to end the lockdown... it hits a die statement. I created a controller... but got lazy...

To end a lockdown, we need to find the active lockdown, change its status to ended, and save it to the database. Easy peasy. But instead of putting that logic inside our controller, let's create a service.

Creating the Service

We could use TDD, but I'm going to create the class quickly, and then we'll test: it'll be easier to understand.

Inside src/Service/, add a new LockdownHelper class. I'll paste in some logic... because it's beautifully boring. We have a method called endCurrentLockDown(), it calls a findMostRecent() method on the repository, sets the status to ENDED and flushes. Up here, we autowire LockdownRepository and EntityManagerInterface.

29 lines | src/Service/LockDownHelper.php
// ... lines 1 - 4
use App\Enum\LockDownStatus;
use App\Repository\LockDownRepository;
use Doctrine\ORM\EntityManagerInterface;
class LockDownHelper
{
public function __construct(
private LockDownRepository $lockDownRepository,
private EntityManagerInterface $entityManager,
)
{
}
public function endCurrentLockDown(): void
{
$lockDown = $this->lockDownRepository->findMostRecent();
if (!$lockDown) {
throw new \LogicException('There is no lock down to end');
}
$lockDown->setStatus(LockDownStatus::ENDED);
$this->entityManager->flush();
}
}

The findMostRecent() method doesn't exist yet on the repository. So open LockDownRepository... and let's do some refactoring. Create a new public function called findMostRecent(), which will return a nullable Lockdown. Then grab the code from below, paste, return that and call it: $lockdown equals $this->findMostRecent().

45 lines | src/Repository/LockDownRepository.php
// ... lines 1 - 17
class LockDownRepository extends ServiceEntityRepository
{
// ... lines 20 - 24
public function findMostRecent(): ?LockDown
{
return $this->createQueryBuilder('lock_down')
->orderBy('lock_down.createdAt', 'DESC')
->setMaxResults(1)
->getQuery()
->getOneOrNullResult();
}
public function isInLockDown(): bool
{
$lockDown = $this->findMostRecent();
// ... lines 37 - 42
}
}

And yes, you could create an integration test for findMostRecent(), but we'll skip it.

Back over in LockDownHelper... this is happy! Before we use this class, let's test it!

Unit Test? Or Integration Test?

The first question is, do we need a unit test or an integration test? And honestly, either would be fine. We could do a unit test, mock LockdownRepository, make sure findMostRecent() is called, and that it sets the status to ENDED and calls flush() on the entity manager. So yea, a unit test would be ok: the mocking isn't too complicated... and it would test the logic pretty well.

Or we can write an integration test, which will run a bit slower, but be more realistic. For the sake of this tutorial, let's do an integration test. And also, you could have both. Heck, there's nothing stopping you from booting the kernel in one test method... and using mocks in another test method in the same class. Mocks and the container are two different tools to help you get your work done.

In the Integration/ directory, create a new Service/ directory... then a new PHP class: LockdownHelperTest. This time, go straight to extending KernelTestCase, then use our two favorite traits: use ResetDatabaseTrait and Factories.

13 lines | tests/Integration/Service/LockDownHelperTest.php
// ... lines 1 - 4
use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
use Zenstruck\Foundry\Test\Factories;
use Zenstruck\Foundry\Test\ResetDatabase;
class LockDownHelperTest extends KernelTestCase
{
use ResetDatabase, Factories;
}

Since we'll use these traits in every integration test, you can also create a base class. Somewhere inside of tests/, you could create an abstract BaseKernelTestCase, put the traits there, then have all of your integration tests extend that.

Down here, let's whip up our test: testEndCurrentLockdown(). And we know how to start: self::bootKernel().

30 lines | tests/Integration/Service/LockDownHelperTest.php
// ... lines 1 - 15
public function testEndCurrentLockdown()
{
self::bootKernel();
// ... lines 19 - 27
}
// ... lines 29 - 30

Let's think. If we're going to end a lockdown... we need an active LockDown in the database. Say $lockdown equals LockDownFactory::createOne()... and pass status set to LockDownStatus::ACTIVE.

30 lines | tests/Integration/Service/LockDownHelperTest.php
// ... lines 1 - 15
public function testEndCurrentLockdown()
{
// ... lines 18 - 19
$lockDown = LockDownFactory::createOne([
'status' => LockDownStatus::ACTIVE,
]);
// ... lines 23 - 27
}
// ... lines 29 - 30

Since we know our database will start empty, we know this will be the item that our query returns. Down here, grab the $lockDownHelper with self::getContainer()->get(LockDownHelper::class)... and use the assert() trick to tell our editor that this is an instanceof LockDownHelper.

30 lines | tests/Integration/Service/LockDownHelperTest.php
// ... lines 1 - 15
public function testEndCurrentLockdown()
{
// ... lines 18 - 23
$lockDownHelper = self::getContainer()->get(LockDownHelper::class);
assert($lockDownHelper instanceof LockDownHelper);
// ... lines 26 - 27
}
// ... lines 29 - 30

With the "Arrange" part of the test done, let's act: $lockDownHelper->endCurrentLockDown().

With any luck, this record should have just changed its status in the database. To prove it, assert that LockDownStatus::ENDED equals $lockDown->getStatus().

30 lines | tests/Integration/Service/LockDownHelperTest.php
// ... lines 1 - 15
public function testEndCurrentLockdown()
{
// ... lines 18 - 25
$lockDownHelper->endCurrentLockDown();
$this->assertSame(LockDownStatus::ENDED, $lockDown->getStatus());
}
// ... lines 29 - 30

Auto-Refreshing in Action

That's a good-looking test! Though there is one tiny detail I should mention. First... I'm going to tell a lie. By checking $lockDown->getStatus(), we're actually only checking that this LockDown object had its status changed by the code... we're not actually testing whether its new value was saved to the database. To test that, we could make a fresh query to the database, like via LockDownFactory::repository()... then find the most recent. We'll talk more about the repository shortcut later.

Now, for the truth. You should be thinking critically about what you're testing or not testing like we just did. However, because we created the $lockDown variable through Foundry, it's wrapped in a Proxy. One of the main features of a Proxy is called "auto-refreshing". Each time you access a property or call a method on your entity, behind the scenes, Foundry queries for the latest data from the database and sets it. So if we hadn't flushed the status change to the database, the test would have failed. Foundry actually would have seen that we had unsaved changes on that entity, and would have yelled at us. Pretty cool.

Inlined or Removed Services?

Ok, let's try this thing! Run:

symfony php vendor/bin/phpunit tests/Integration/Service/LockDownHelperTest.php

And... what the heck? It says:

The LockDownHelper service or alias has been removed or inlined when the container was compiled.

What does that mean? Ok, a really cool thing about Symfony's service container is that if a service isn't used by anything in your app, it's removed from the container... which makes our app leaner and meaner.

In our actual application code, like controllers, repositories & services, nobody is using the LockDownHelper service. We're not autowiring it into a controller or a service anywhere. And so, Symfony removes this from the container... which means that it's not there in the test.

The fix for this is... just to make sure it's used somewhere! I mean, if we're writing this code, certainly we intended to... ya know, use it.

In the endLockDown() action, autowire LockDownHelper $lockDownHelper... and I'm not even going to call anything on it yet. Just having it here will be enough.

42 lines | src/Controller/MainController.php
// ... lines 1 - 8
use App\Service\LockDownHelper;
// ... lines 10 - 14
class MainController extends AbstractController
{
// ... lines 17 - 32
public function endLockDown(Request $request, LockDownHelper $lockDownHelper)
{
// ... lines 35 - 39
}
}

And now:

symfony php vendor/bin/phpunit tests/Integration/Service/LockDownHelperTest.php

The test passes! Woo!

Let's use it: call $lockDownHelper->endCurrentLockDown()... then redirect back to the homepage.

44 lines | src/Controller/MainController.php
// ... lines 1 - 32
public function endLockDown(Request $request, LockDownHelper $lockDownHelper)
{
// ... lines 35 - 38
$lockDownHelper->endCurrentLockDown();
return $this->redirectToRoute('app_homepage');
}
// ... lines 43 - 44

Let's try it! Refresh, we're in a lockdown... "End Lockdown"... it's gone. All the dinos are back in their pens.

Next: I'm going to complicate things by introducing a situation that will make us want to unit test and integration test LockDownHelper... at the same time. That'll lead us to something I call "partial mocking".