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feat: Implement lazy listeners and lazy listener subscriber
Combines the features of LazyListener and LazyEventListener into `Zend\EventManager\ListenerProvider\LazyListener`. `LazyListenerSubscriber` is based on `LazyListenerAggregate`, but simplifies it by having it compose `LazyListener` instances only (no creation within it).
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‎TODO-PSR-14.md

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@@ -51,15 +51,16 @@
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- [x] `detach(PrioritizedListenerAttachmentInterface $provider)`
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- [x] Create `AbstractListenerSubscriber` and/or `ListenerSubscriberTrait`
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- [x] define a default `detach()` implementation
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- [ ] Create `LazyListenerSubscriber` based on `LazyListenerAggregate`
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- [ ] Define an alternate LazyListener:
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- [ ] `__construct(ContainerInterface $container, string $event = null, int $priority = 1)`
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- [ ] implements functionality from both `LazyListener` and `LazyEventListener`, minus passing env to container
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- [ ] without an event, can be attached to any provider
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- [ ] with an event, can be attached to `LazyListenerSubscriber`
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- Constructor aggregates `LazyListener` _instances_ only
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- [ ] `attach()` skips any where `getEvent()` returns null
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- [x] Create `LazyListenerSubscriber` based on `LazyListenerAggregate`
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- [x] Define an alternate LazyListener:
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- [x] `__construct(ContainerInterface $container, string $event = null, int $priority = 1)`
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- [x] implements functionality from both `LazyListener` and `LazyEventListener`, minus passing env to container
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- [x] without an event, can be attached to any provider
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- [x] with an event, can be attached to `LazyListenerSubscriber`
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- [x] Constructor aggregates `LazyListener` _instances_ only
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- [x] raises exception when `getEvent()` returns null
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- [ ] Event Dispatcher implementation
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- [ ] Implement `PrioritizedListenerAttachmentInterface` (if BC)
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- [ ] Create a `PrioritizedListenerProvider` instance in the `EventManger`
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constructor, and have the various `attach()`, `detach()`, etc. methods
6566
proxy to it.

‎src/ListenerProvider/LazyListener.php

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<?php
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/**
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* @see https://github.com/zendframework/zend-eventmanager for the canonical source repository
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* @copyright Copyright (c) 2019 Zend Technologies USA Inc. (https://www.zend.com)
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* @license https://github.com/zendframework/zend-eventmanager/blob/master/LICENSE.md New BSD License
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*/
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namespace Zend\EventManager\ListenerProvider;
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use Psr\Container\ContainerInterface;
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use Zend\EventManager\Exception;
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/**
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* Lazy listener instance.
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*
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* Used to allow lazy creation of listeners via a dependency injection
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* container.
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*/
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class LazyListener
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{
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/**
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* @var ContainerInterface Container from which to pull listener.
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*/
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private $container;
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/**
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* @var null|string Event name to which to attach; for use with
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* ListenerSubscriberInterface instances.
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*/
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private $event;
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/**
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* @var object Service pulled from container
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*/
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private $listener;
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/**
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* @var string Method name to invoke on listener.
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*/
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private $method;
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/**
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* @var null|int Priority at which to attach; for use with
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* ListenerSubscriberInterface instances.
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*/
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private $priority;
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/**
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* @var string Service name of listener.
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*/
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private $service;
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/**
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* @param ContainerInterface $container Container from which to pull
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* listener service
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* @param string $listener Name of listener service to retrive from
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* container
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* @param null|string $method Name of method on listener service to use
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* when calling listener; defaults to __invoke.
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* @param null|string $event Name of event to which to attach; for use
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* with ListenerSubscriberInterface instances. In that scenario, null
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* indicates it should attach to any event.
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* @param null|int $priority Priority at which to attach; for use with
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* ListenerSubscriberInterface instances. In that scenario, null indicates
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* that the default priority should be used.
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* @throws Exception\InvalidArgumentException for invalid $listener arguments
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* @throws Exception\InvalidArgumentException for invalid $method arguments
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* @throws Exception\InvalidArgumentException for invalid $event arguments
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*/
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public function __construct(
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ContainerInterface $container,
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$listener,
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$method = '__invoke',
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$event = null,
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$priority = null
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) {
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if (! is_string($listener) || empty($listener)) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s requires a non-empty string $listener argument'
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. ' representing a service name; received %s',
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__CLASS__,
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gettype($listener)
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));
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}
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if (! is_string($method)
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|| ! preg_match('/^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$/', $method)
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) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s requires a valid string $method argument; received %s',
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__CLASS__,
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is_string($method) ? sprintf('"%s"', $method) : gettype($method)
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));
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}
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if (null !== $event && (! is_string($event) || empty($event))) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s requires a null or non-empty string $event argument; received %s',
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__CLASS__,
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is_string($event) ? sprintf('"%s"', $event) : gettype($event)
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));
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}
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$this->container = $container;
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$this->service = $listener;
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$this->method = $method;
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$this->event = $event;
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$this->priority = $priority;
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}
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/**
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* Use the listener as an invokable, allowing direct attachment to an event manager.
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*
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* @param object $event
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* @return void
116+
*/
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public function __invoke($event)
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{
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$listener = $this->fetchListener();
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$method = $this->method;
121+
$listener->{$method}($event);
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}
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/**
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* @return null|string
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*/
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public function getEvent()
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{
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return $this->event;
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}
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/**
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* Return the priority, or, if not set, the default provided.
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*
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* @param int $default
136+
* @return int
137+
*/
138+
public function getPriority($default = 1)
139+
{
140+
return null !== $this->priority ? (int) $this->priority : (int) $default;
141+
}
142+
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/**
144+
* @return callable
145+
*/
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private function fetchListener()
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{
148+
if ($this->listener) {
149+
return $this->listener;
150+
}
151+
152+
$this->listener = $this->container->get($this->service);
153+
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return $this->listener;
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}
156+
}

‎src/ListenerProvider/LazyListenerSubscriber.php

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<?php
2+
/**
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* @see https://github.com/zendframework/zend-eventmanager for the canonical source repository
4+
* @copyright Copyright (c) 2019 Zend Technologies USA Inc. (https://www.zend.com)
5+
* @license https://github.com/zendframework/zend-eventmanager/blob/master/LICENSE.md New BSD License
6+
*/
7+
8+
namespace Zend\EventManager\ListenerProvider;
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10+
use Zend\EventManager\Exception;
11+
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/**
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* Listener subscriber for attaching lazy listeners.
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*
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* Lazy listeners are listeners where creation is deferred until they are
16+
* triggered; this removes the most costly mechanism of pulling a listener
17+
* from a container unless the listener is actually invoked.
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*
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* Usage is:
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*
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* <code>
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* $subscriber = new LazyListenerSubscriber($listOfLazyListeners);
23+
* $subscriber->attach($provider, $priority);
24+
* ));
25+
* </code>
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*/
27+
class LazyListenerSubscriber implements ListenerSubscriberInterface
28+
{
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/**
30+
* LazyListener instances.
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*
32+
* @var LazyListener[]
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*/
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private $listeners = [];
35+
36+
/**
37+
* @throws Exception\InvalidArgumentException if any member of $listeners
38+
* is not a LazyListener instance.
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* @throws Exception\InvalidArgumentException if any member of $listeners
40+
* does not have a defined event to which to attach.
41+
*/
42+
public function __construct(array $listeners)
43+
{
44+
$this->validateListeners($listeners);
45+
$this->listeners = $listeners;
46+
}
47+
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/**
49+
* Subscribe listeners to the provider.
50+
*
51+
* Loops through all composed lazy listeners, and attaches them to the
52+
* provider.
53+
*/
54+
public function attach(PrioritizedListenerAttachmentInterface $provider, $priority = 1)
55+
{
56+
foreach ($this->listeners as $listener) {
57+
$provider->attach(
58+
$listener->getEvent(),
59+
$listener,
60+
$listener->getPriority($priority)
61+
);
62+
}
63+
}
64+
65+
public function detach(PrioritizedListenerAttachmentInterface $provider)
66+
{
67+
foreach ($this->listeners as $listener) {
68+
$provider->detach($listener, $listener->getEvent());
69+
}
70+
}
71+
72+
/**
73+
* @throws Exception\InvalidArgumentException if any member of $listeners
74+
* is not a LazyListener instance.
75+
* @throws Exception\InvalidArgumentException if any member of $listeners
76+
* does not have a defined event to which to attach.
77+
*/
78+
private function validateListeners(array $listeners)
79+
{
80+
foreach ($listeners as $index => $listener) {
81+
if (! $listener instanceof LazyListener) {
82+
throw new Exception\InvalidArgumentException(sprintf(
83+
'%s only accepts %s instances; received listener of type %s at index %s',
84+
__CLASS__,
85+
LazyListener::class,
86+
gettype($listener),
87+
$index
88+
));
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}
90+
91+
if (null === $listener->getEvent()) {
92+
throw new Exception\InvalidArgumentException(sprintf(
93+
'%s requires that all %s instances compose a non-empty string event to which to attach;'
94+
. ' none provided for listener at index %s',
95+
__CLASS__,
96+
LazyListener::class,
97+
$index
98+
));
99+
}
100+
}
101+
}
102+
}

‎test/ListenerProvider/LazyListenerSubscriberTest.php

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<?php
2+
/**
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* @see https://github.com/zendframework/zend-eventmanager for the canonical source repository
4+
* @copyright Copyright (c) 2019 Zend Technologies USA Inc. (https://www.zend.com)
5+
* @license https://github.com/zendframework/zend-eventmanager/blob/master/LICENSE.md New BSD License
6+
*/
7+
8+
namespace ZendTest\EventManager\ListenerProvider;
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10+
use PHPUnit\Framework\TestCase;
11+
use Prophecy\Argument;
12+
use Zend\EventManager\Exception\InvalidArgumentException;
13+
use Zend\EventManager\ListenerProvider\LazyListener;
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use Zend\EventManager\ListenerProvider\LazyListenerSubscriber;
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use Zend\EventManager\ListenerProvider\PrioritizedListenerAttachmentInterface;
16+
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class LazyListenerAggregateTest extends TestCase
18+
{
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public function setUp()
20+
{
21+
$this->container = $this->prophesize(ContainerInterface::class);
22+
}
23+
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public function invalidListenerTypes()
25+
{
26+
return [
27+
'null' => [null],
28+
'true' => [true],
29+
'false' => [false],
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'zero' => [0],
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'int' => [1],
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'zero-float' => [0.0],
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'float' => [1.1],
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'string' => ['listener'],
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'array' => [['listener']],
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'object' => [(object) ['event' => 'event', 'listener' => 'listener', 'method' => 'method']],
37+
];
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}
39+
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/**
41+
* @dataProvider invalidListenerTypes
42+
*/
43+
public function testPassingInvalidListenerTypesAtInstantiationRaisesException($listener)
44+
{
45+
$this->expectException(InvalidArgumentException::class);
46+
$this->expectExceptionMessage('only accepts ' . LazyListener::class . ' instances');
47+
new LazyListenerSubscriber([$listener]);
48+
}
49+
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public function testPassingLazyListenersMissingAnEventAtInstantiationRaisesException()
51+
{
52+
$listener = $this->prophesize(LazyListener::class);
53+
$listener->getEvent()->willReturn(null);
54+
55+
$this->expectException(InvalidArgumentException::class);
56+
$this->expectExceptionMessage('compose a non-empty string event');
57+
new LazyListenerSubscriber([$listener->reveal()]);
58+
}
59+
60+
public function testAttachesLazyListenersToProviderUsingEventAndPriority()
61+
{
62+
$listener = $this->prophesize(LazyListener::class);
63+
$listener->getEvent()->willReturn('test');
64+
$listener->getPriority(1000)->willReturn(100);
65+
66+
$subscriber = new LazyListenerSubscriber([$listener->reveal()]);
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$provider = $this->prophesize(PrioritizedListenerAttachmentInterface::class);
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$provider->attach('test', $listener->reveal(), 100)->shouldBeCalledTimes(1);
70+
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$this->assertNull($subscriber->attach($provider->reveal(), 1000));
72+
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return [
74+
'listener' => $listener,
75+
'subscriber' => $subscriber,
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'provider' => $provider,
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];
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}
79+
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/**
81+
* @depends testAttachesLazyListenersToProviderUsingEventAndPriority
82+
*/
83+
public function testDetachesLazyListenersFromProviderUsingEvent(array $dependencies)
84+
{
85+
$listener = $dependencies['listener'];
86+
$subscriber = $dependencies['subscriber'];
87+
$provider = $dependencies['provider'];
88+
89+
$provider->detach($listener->reveal(), 'test')->shouldBeCalledTimes(1);
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$this->assertNull($subscriber->detach($provider->reveal()));
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}
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}

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