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Hooks: setUp, tearDown & Skipping Tests

We can also use the TDD refactor step to improve our tests! Eventually, we're going to have a lot of test methods inside DinosaurFactoryTest. And each one will need to create the DinosaurFactory object. If that class eventually has some constructor arguments, that's going to be a pain!

The setUp Hook

Add a new $factory property and give it some PHPDoc: this will be a DinosaurFactory object. Then - here's the magic part - create a new public function setUp(). Inside, set the property to a new DinosaurFactory.

36 lines tests/AppBundle/Factory/DinosaurFactoryTest.php
... lines 1 - 8
class DinosaurFactoryTest extends TestCase
{
/**
* @var DinosaurFactory
*/
private $factory;
... line 15
public function setUp()
{
$this->factory = new DinosaurFactory();
}
... lines 20 - 34
}

Back in our test method, use the new property. Yep, this will work... but only thanks to a bit of PHPUnit magic. If you have a method that's exactly called setUp, PHPUnit will automatically call it before each test.

36 lines tests/AppBundle/Factory/DinosaurFactoryTest.php
... lines 1 - 8
class DinosaurFactoryTest extends TestCase
{
... lines 11 - 20
public function testItGrowsALargeVelociraptor()
{
$dinosaur = $this->factory->growVelociraptor(5);
... lines 24 - 28
}
... lines 30 - 34
}

If you have multiple test functions, that means that setUp will be called before each test method. This will make sure that the $factory property is a new, fresh DinosaurFactory object for every test. And that's really important: each test should be completely independent of each other. You never want one test to rely on something a different test set up first. Why? Because later, we'll learn how to execute just one test at a time - which is really useful for debugging.

Other Hooks: tearDown, setUpAfterClass, etf

There are a few other magic methods like this. The most common is tearDown(), which is the opposite of setUp. It's still called once per test, but after the test is executed. It's meant for cleanup, and we'll talk more about it later.

Two other useful hook methods are setUpBeforeClass() and tearDownAfterClass. Instead of being called before or after every test, these are called once for the entire class. They're less common, but if you need to setup something global or static, this is the place to do it.

Oh, and one last, lesser-known hook method is onNotSuccessfulTest. Sometimes I'll use that to print extra debugging info.

Ok, make sure the tests still pass!

./vendor/bin/phpunit

Perfect!

Marking Tests as Incomplete

Our dinosaur park guests are really excited about seeing some triceratops! But... we can't grow them yet - the scientists are still working on that dino DNA.

But eventually, we're going to add a growTriceratops method to DinosaurFactory. To make sure we don't forget about this, let's start the test: testItGrowsATriceratops. But I don't really want this test to exist... and fail - that's lame. Instead, add $this->markTestIncomplete('Waiting for confirmation from GenLab').

47 lines tests/AppBundle/Factory/DinosaurFactoryTest.php
... lines 1 - 8
class DinosaurFactoryTest extends TestCase
{
... lines 11 - 30
public function testItGrowsATriceraptors()
{
$this->markTestIncomplete('Waiting for confirmation from GenLab');
}
... lines 35 - 45
}

Try it!

./vendor/bin/phpunit

Nice! It's not a failure... just a clear marker to remind us that we have work to do!

Skipping Tests

A similar thing you can do is skip tests. Try this: add a new method: testItGrowsABabyVelociraptor(). Create a tiny velociraptor - adorable! - and make sure it's length is correct.

47 lines tests/AppBundle/Factory/DinosaurFactoryTest.php
... lines 1 - 8
class DinosaurFactoryTest extends TestCase
{
... lines 11 - 35
public function testItGrowsABabyVelociraptor()
{
... lines 38 - 41
$dinosaur = $this->factory->growVelociraptor(1);
$this->assertSame(1, $dinosaur->getLength());
}
}

This will totally work. But let's pretend that, inside the growVelociraptor() method, we use some class or PHP extension that the user may or may not have installed. Check to see if some imaginary Nanny class exists. If it doesn't, we can't run the test! So mark it as skipped: there's nobody to watch the baby raptor!

47 lines tests/AppBundle/Factory/DinosaurFactoryTest.php
... lines 1 - 8
class DinosaurFactoryTest extends TestCase
{
... lines 11 - 35
public function testItGrowsABabyVelociraptor()
{
if (!class_exists('Nanny')) {
$this->markTestSkipped('There is nobody to watch the baby!');
}
... lines 41 - 44
}
}

./vendor/bin/phpunit

When you run the tests now... cool! An I for incomplete and S for skipped.

I don't use markTestSkipped() in my own apps - it's a bit more useful when you're building some reusable library and need to write tests for optional features that use optional libraries. It's used all the time inside Symfony's core.

Next! I want to talk about my favorite feature in PHPUnit: data providers!

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