TestDoubleBundle
What ?
A symfony bundle that eases creation of test doubles., (*1)
Using DIC tags, you can automatically replace a service with either a stub or a fake., (*2)
Why ?
To improve isolation of tests and increase the precision and variation of test fixtures., (*3)
Usually, our behat suite is using real data, coming from database fixtures.
This forces us to create gobal, universal, works-for-all fixtures., (*4)
A real database also implies to reset the state before each scenario.
This process is slow, and is just a workaround for having broken isolation., (*5)
An ideal test suite would run each scenario using only in-memory repositories.
Each scenario should define how the SUS behaves given a specific context.
Having a global implicit context (the database fixtures) makes it really hard to test different cases., (*6)
One solution is to replace your repositories with stubs.
Each scenario configures only the stubs required for it to work., (*7)
Note: Stubbed data is not resilient across processes,
and thus doesn't fit for end-to-end testing like a typical mink+behat suite., (*8)
But now that repositories are doubled, how do you know if your real repositories still work?
Well, that's the role of infrastructure tests. Only those run against a real backend,
be it a database for repositories, or a server for an http client., (*9)
To access the real services, just use <original-id>.real., (*10)
By doing that, you theoretically have a good coverage, isolation, speed
and you can better catch the origin of a regression., (*11)
All this while applying modelling by example., (*12)
How ?
install
composer require docteurklein/test-double-bundle --dev
register the bundle
``` php, (*13)
public function registerBundles()
{
$bundles = [
new \DocteurKlein\TestDoubleBundle,
// …
];
return $bundles;
}
> Note: You might want to add this bundle only in test env.
### integrate with behat
This approach integrates very well with the [Symfony2Extension](https://github.com/Behat/Symfony2Extension/blob/master/doc/index.rst#injecting-services).
You can then inject the service and/or the prophecy in your context class.
You can also inject the container and access all the services at once.
## Examples
> Note: The following examples use JmsDiExtraBundle to simplify code.
### Stubs
Stubs are created using [prophecy](https://github.com/phpspec/prophecy).
> Note: if you don't provide any tag attribute, then a stub is created.
> if no class or interface is given to the `stub` attribute, then a stub for the service class will be created.
> A stubbed class cannot be final.
- First, define a stub DIC tag for the service
``` php
/**
* @Service("github_client")
* @Tag("test_double", attributes={"stub"="GithubClient"})
*/
final class GuzzleClient implements GithubClient
{
public function addIssue(Issue $issue)
{
// …
}
}
- Automatically, the original
github_client service is replaced with the github_client.stub service.
In order to control this stub, you have to use the github_client.prophecy service:, (*14)
``` php
$issue = new Issue('test');
$container->get('github_client.prophecy')->addIssue($issue)->willReturn(true);, (*15)
### Fake
> Note: fakes are really just DIC aliases.
Imagine you have a service you want to double.
- First, create this service and add a tag with the corresponding fake service:
``` php
/**
* @Service("github_client")
* @Tag("test_double", attributes={"fake"="github_client.fake"})
*/
final class GuzzleClient implements GithubClient
{
public function addIssue(Issue $issue)
{
// …
}
}
- Then, create a fake implementation and register it with the fake id:
``` php
/**
* @Service("github_client.fake")
*/
final class FakeClient implements GithubClient
{
public function addIssue(Issue $issue)
{
// …
}
}, (*16)
### Behat
> Note: We tagged `repo.invoices` and `http.client` as **stub**.
``` php
class Domain implements Context
{
public function __construct($container)
{
$this->container = $container;
}
/**
* @Given a building in "maintenance mode"
*/
public function aBuildingInMaintenanceMode()
{
$this->building = new Building('BUILDING1337');
$this->building->putInMaintenanceMode();
}
/**
* @When its last unpaid invoice is being paid
*/
public function itsLastUnpaidInvoiceIsBeingPaid()
{
$this->container
->get('repo.invoices.prophecy')
->findOneByReference('UNPAID04')
->willReturn(Invoice::ownedBy($this->building))
;
$pay = $this->container->get('app.task.invoice.pay');
$pay('UNPAID04');
}
/**
* @Then it should be removed from maintenance mode
*/
public function itShouldBeRemovedFromMaintenanceMode()
{
$this->container
->get('http.client.prophecy')
->removeFromMaintenanceMode('BUILDING1337')
->shouldHaveBeenCalled()
;
$this->container->get('stub.prophet')->checkPredictions();
}
}
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