/**
* return a read-only list of event handlers for a given event from
* a given event stream
*
* @param EventStream $stream
* the stream to extract from
* @param string $eventName
* the event to get the handler list for
* @return array<callable>
* the list of handlers for the event
* can be an empty list
*/
public static function from(EventStream $stream, $eventName)
{
// defensive programming
RequireEventName::check($eventName);
if (!isset($stream->{$eventName})) {
return [];
}
return $stream->{$eventName};
}
/**
* We want $eventHandler to be called whenever an event of type $eventName
* is dispatch to the event stream $stream
*
* @param EventStream $stream
* the stream we want to register the event handler on
* @param string $eventName
* the event we want to handle
* @param callable $eventHandler
* the handler we want called
* @return void
*/
public static function on(EventStream $stream, $eventName, $eventHandler)
{
RequireEventName::check($eventName);
RequireCallable::check($eventHandler, E4xx_UnsupportedType::class);
if (!isset($stream->{$eventName})) {
$stream->{$eventName} = [];
}
$stream->{$eventName}[] = $eventHandler;
}
/**
* @covers ::check
* @dataProvider provideEverythingElse
* @expectedException GanbaroDigital\EventStream\Exceptions\E4xx_NotAnEvent
*/
public function testThrowsExceptionForEverythingElse($eventName)
{
// ----------------------------------------------------------------
// setup your test
// ----------------------------------------------------------------
// perform the change
RequireEventName::check($eventName);
// ----------------------------------------------------------------
// test the results
//
// if we get here with no exception, the test has failed
}