Allow for a candidate to have a Closure as a class parameter

src/ClassDiscovery.php

@@ -2,6 +2,7 @@
 
 namespace Http\Discovery;
 
+use Http\Discovery\Exception\ClassinstantiationFailedException;
 use Http\Discovery\Exception\DiscoveryFailedException;
 use Http\Discovery\Exception\StrategyUnavailableException;
 
@@ -36,7 +37,7 @@ abstract class ClassDiscovery
      *
      * @param string $type
      *
-     * @return string
+     * @return string|\Closure
      *
      * @throws DiscoveryFailedException
      */
@@ -177,4 +178,28 @@ protected static function evaluateCondition($condition)
 
         return false;
     }
+
+    /**
+     * Get an instance of the $class.
+     *
+     * @param string|\Closure $class A FQN of a class or a closure that instantiate the class.
+     *
+     * @return object
+     */
+    protected static function instantiateClass($class)
+    {
+        try {
+            if (is_string($class)) {
+                return new $class();
+            }
+
+            if (is_callable($class)) {
+                return $class();
+            }
+        } catch (\Exception $e) {
+            throw new ClassinstantiationFailedException('Unexcepced exception when instantiating class.', 0, $e);
+        }
+
+        throw new ClassinstantiationFailedException('Could not instantiate class becuase parameter is neitehr a callable or a string');
+    }
 }

src/Exception/ClassinstantiationFailedException.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+use Http\Discovery\Exception;
+
+/**
+ * Thrown when a class fails to instantiate.
+ *
+ * @author Tobias Nyholm <[email protected]>
+ */
+class ClassinstantiationFailedException extends \RuntimeException implements Exception
+{
+}

src/HttpAsyncClientDiscovery.php

@@ -24,7 +24,7 @@ public static function find()
         try {
             $asyncClient = static::findOneByType(HttpAsyncClient::class);
 
-            return new $asyncClient();
+            return static::instantiateClass($asyncClient);
         } catch (DiscoveryFailedException $e) {
             throw new NotFoundException(
                 'No HTTPlug async clients found. Make sure to install a package providing "php-http/async-client-implementation". Example: "php-http/guzzle6-adapter".',

src/HttpClientDiscovery.php

@@ -24,7 +24,7 @@ public static function find()
         try {
             $client = static::findOneByType(HttpClient::class);
 
-            return new $client();
+            return static::instantiateClass($client);
         } catch (DiscoveryFailedException $e) {
             throw new NotFoundException(
                 'No HTTPlug clients found. Make sure to install a package providing "php-http/client-implementation". Example: "php-http/guzzle6-adapter".',

src/MessageFactoryDiscovery.php

@@ -24,7 +24,7 @@ public static function find()
         try {
             $messageFactory = static::findOneByType(MessageFactory::class);
 
-            return new $messageFactory();
+            return static::instantiateClass($messageFactory);
         } catch (DiscoveryFailedException $e) {
             throw new NotFoundException(
                 'No message factories found. To use Guzzle or Diactoros factories install php-http/message and the chosen message implementation.',

src/StreamFactoryDiscovery.php

@@ -24,7 +24,7 @@ public static function find()
         try {
             $streamFactory = static::findOneByType(StreamFactory::class);
 
-            return new $streamFactory();
+            return static::instantiateClass($streamFactory);
         } catch (DiscoveryFailedException $e) {
             throw new NotFoundException(
                 'No stream factories found. To use Guzzle or Diactoros factories install php-http/message and the chosen message implementation.',

src/UriFactoryDiscovery.php

@@ -24,7 +24,7 @@ public static function find()
         try {
             $uriFactory = static::findOneByType(UriFactory::class);
 
-            return new $uriFactory();
+            return static::instantiateClass($uriFactory);
         } catch (DiscoveryFailedException $e) {
             throw new NotFoundException(
                 'No uri factories found. To use Guzzle or Diactoros factories install php-http/message and the chosen message implementation.',