Test factory callability more simply, so psalm understands what's hap…

…pening

Signed-off-by: Tim Lieberman <[email protected]>

src/FlashMessageMiddleware.php

@@ -11,9 +11,7 @@
 use Psr\Http\Server\MiddlewareInterface;
 use Psr\Http\Server\RequestHandlerInterface;
 
-use function class_exists;
-use function class_implements;
-use function in_array;
+use function is_callable;
 
 class FlashMessageMiddleware implements MiddlewareInterface
 {
@@ -22,10 +20,7 @@ class FlashMessageMiddleware implements MiddlewareInterface
     /** @var string */
     private $attributeKey;
 
-    /**
-     * @var callable
-     * @psalm-var callable(SessionInterface, string):array
-     */
+    /** @psalm-var callable(SessionInterface, string): FlashMessagesInterface */
     private $flashMessageFactory;
 
     /** @var string */
@@ -36,15 +31,12 @@ public function __construct(
         string $sessionKey = FlashMessagesInterface::FLASH_NEXT,
         string $attributeKey = self::FLASH_ATTRIBUTE
     ) {
-        if (
-            ! class_exists($flashMessagesClass)
-            || ! in_array(FlashMessagesInterface::class, class_implements($flashMessagesClass), true)
-        ) {
+        $factory = [$flashMessagesClass, 'createFromSession'];
+        if (! is_callable($factory)) {
             throw Exception\InvalidFlashMessagesImplementationException::forClass($flashMessagesClass);
         }
 
-        /** @psalm-var callable(SessionInterface, string):array */
-        $this->flashMessageFactory = [$flashMessagesClass, 'createFromSession'];
+        $this->flashMessageFactory = $factory;
         $this->sessionKey          = $sessionKey;
         $this->attributeKey        = $attributeKey;
     }