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14.

Resetting the Database Between Tests

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One of the trickiest things about functional tests is controlling the database. In my opinion, a perfect world is one where the database is completely empty at the start of each test. That would give us a completely predictable state where we could create whatever User or CheeseListing objects we want and know exactly what's in the database.

Some people prefer to go a step further and load a predictable set of "fixtures" data before each test - like a few users and some cheese listings. That's fine, but it's not the approach I prefer. Why? Because if we can make the database empty, then each test is forced to create whatever data - like users or cheese listings - that it needs. That might sound bad at first... because... that's more work! But the end result is that each test reads like a complete story: we can see that we get a 401 status code, then we create a user, then we log in with the user we just created. A nice, complete story.

Installing Alice

So... how can we empty the database before each test? There are a few answers, but one common one you'll see in the API Platform world is called Alice. Find your terminal and install it with:

composer require "alice:^2.7" --dev

This will install hautelook/alice-bundle. What does that bundle actually do? I've talked about it a few times in the past on SymfonyCasts: it allows you to specify fixtures data via YAML. It's really fun actually and has some nice features for quickly creating a set of objects, using random data and linking objects to each other. It was the inspiration behind a fixture class that we created and used in our Symfony Doctrine tutorial. The recipe creates a fixtures/ directory for the YAML files and a new command for loading that data.

The ReloadDatabaseTrait

But... what does any of that have to do with testing? Nothing! It's just a way to load fixture data and you can use it... or not use it. But AliceBundle has an extra, unrelated, feature that helps manage your database in the test environment.

Back in our test class... once PHPStorm finishes reindexing we're going to use a new trait: use ReloadDatabaseTrait.

41 lines | tests/Functional/CheeseListingResourceTest.php
// ... lines 1 - 6
use Hautelook\AliceBundle\PhpUnit\ReloadDatabaseTrait;
// ... line 8
class CheeseListingResourceTest extends ApiTestCase
{
use ReloadDatabaseTrait;
// ... lines 12 - 39
}

That's it! Just by having this, before each test method is called, the trait will handle emptying our database tables and reloading our Alice YAML fixtures... which of course we don't have. So, it'll just empty the database.

Try it!

php bin/phpunit

We see even more deprecation warnings now - the AliceBundle has a few deprecations it needs to take care of - but it works! We can run it over and over again... it always passes because the database always starts empty. This is a huge step towards having dependable, readable tests.

Removing the Logging Output

While we're here, we're getting this odd log output at the top of our tests. I can tell that this is coming from Symfony... it's almost like each time an "error" log is triggered in our code, it's being printed here. That's... ok... but why? Symfony normally stores log files in var/logs/test.log, for the test environment.

The answer is... because we never installed a logger! Internally, Symfony ships with its own logger service so that if any other services or bundles want to log something, it's available! But that logger is super simple... on purpose: it's just meant as a fallback logger if nothing better is installed. Instead of writing to a file, it logs errors to stderr... which basically means they get printed to the screen from the command line.

Let's install a real logger:

composer require "logger:^3.4"

This installs Monolog. When it finishes... try running the tests again:

php bin/phpunit

And... no more output! Now the logs are stored in var/log/test.log. If you tail that file...

tail -f var/log/test.log

there it is!

Next, I want to make one more improvement to our test suite before we get back to talking about API Platform security. I want to create a base test class with some helper methods that will enable us to move fast and write clean code in our tests.