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#Using Spin In Behat
As our Behat tests are pretty slow, we had issues waiting for some Element to appear in pages. Sometimes an Element is not found because the page isn’t completely loaded. In this case, waiting two or three extra seconds could help finding elements.
Learn about spin from Behat documentation.
#Use the SpinCapableTrait
In Akeneo PIM we use spin as a Trait. To be able to use the spin method you only have to add the Trait in your decorator or your context as follows:
use Context\Spin\SpinCapableTrait;
use Pim\Behat\Decorator\ElementDecorator;
MyClassDecorator extends ElementDecorator {
use SpinCapableTrait;
}
#Spin Signature
In the method signature you can see two arguments.
// Context\Spin\SpinCapableTrait
public function spin($callable, $message) {}
The first one is a callable function. This function is where you search for your Element. If this callable returns false, null or throws an exception, the spin will retry every second the callable function until it returns a value or when the loop limit is reached.
The second one is the message that will be written in the console in case the loop limit is reached.
#Example
Let’s see an example from the PermissionDecorator:
/**
* @param string $group
*
* @return NodeElement
*/
public function findGroup($group)
{
return $this->spin(function () use ($group) {
return $this->find('css', sprintf('.tab-groups .tab:contains("%s")', $group));
}, sprintf('Group "%s" not found.', $group));
}
Here we want to find an Element which contains the text $group. Searching for this Element in the page without spinning may not work as the loading of the page might not be complete. Waiting for the page to be completely loaded can lead to a significant time waiting, all the while knowing we can never be certain when this event will actually occur. Thanks to the spin, we just have to wait for a specific Element to appear. That’s why we never use the wait method from Behat.
Usually, we avoid adding actions on elements like click(), check(), etc. in spin, but sometimes it is unavoidable to perform a series of find with actions to deploy a panel or click on a button to reveal a field.
#Inform That Spin Failed
There are two ways to inform the developer the callable function has failed. The first one is to fill the second argument of the spin $message which was previously mentioned. The second one is to throw a SpinException from the callable. If an exception is thrown from the spin, the result is that the spin will retry and the $message will be replaced by the SpinException message.
Make sure to send a clear message with as much indications as you can provide to the developer about the location and the reason why the callable has failed.
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