Implement callable initializer for "connections" client option.

lib/Predis/Option/ClientConnectionFactory.php

@@ -40,8 +40,20 @@ class ClientConnectionFactory extends AbstractOption
             return $factory;
         }
 
-        if (is_string($value) && class_exists($value)) {
-            if (!($factory = new $value()) && !$factory instanceof ConnectionFactoryInterface) {
+        if (is_callable($value)) {
+            $factory = call_user_func($value, $options, $this);
+
+            if (!$factory instanceof ConnectionFactoryInterface) {
+                throw new \InvalidArgumentException('Instance of Predis\Connection\ConnectionFactoryInterface expected');
+            }
+
+            return $factory;
+        }
+
+        if (@class_exists($value)) {
+            $factory = new $value();
+
+            if (!$factory instanceof ConnectionFactoryInterface) {
                 throw new \InvalidArgumentException("Class $value must be an instance of Predis\Connection\ConnectionFactoryInterface");
             }
 

tests/Predis/Option/ClientConnectionFactoryTest.php

@@ -61,6 +61,27 @@ class ClientConnectionFactoryTest extends StandardTestCase
         $this->assertSame($value, $option->filter($options, $value));
     }
 
+    /**
+     * @group disconnected
+     */
+    public function testValidationAcceptsCallableObjectAsInitializers()
+    {
+        $value = $this->getMock('Predis\Connection\ConnectionFactoryInterface');
+        $options = $this->getMock('Predis\Option\ClientOptionsInterface');
+        $option = new ClientConnectionFactory();
+
+        $initializer = $this->getMock('stdClass', array('__invoke'));
+        $initializer->expects($this->once())
+                    ->method('__invoke')
+                    ->with($this->isInstanceOf('Predis\Option\ClientOptionsInterface'), $option)
+                    ->will($this->returnValue($value));
+
+        $cluster = $option->filter($options, $initializer, $option);
+
+        $this->assertInstanceOf('Predis\Connection\ConnectionFactoryInterface', $cluster);
+        $this->assertSame($value, $cluster);
+    }
+
     /**
      * @group disconnected
      */