Add AssertingMessageBus

README.md

@@ -47,6 +47,10 @@ The message handler provider is a callable with a signature similar to the
 that only requires an array of key/value pairs, where _key_ is a message class and _value_
 a message handler callable.
 
+
+
+
+
 ### Providing handlers
 
 The following example demonstrates how to define a message handler provider with a selection
@@ -75,6 +79,10 @@ $message_handler_provider = new SimpleMessageHandlerProvider([
 ]);
 ```
 
+
+
+
+
 ### Providing handlers with icanboogie/service
 
 Of course, if you're using the [icanboogie/service][] package, you can use service references
@@ -156,6 +164,30 @@ $provider = $container->get(AddCommandBusPass::DEFAULT_PROVIDER_SERVICE);
 
 
 
+## Asserting messages before dispatching
+
+The [AssertingMessageBus][] decorator can be used to assert message before they are dispatched. One
+could use the assertion to reject messages that require special permissions.
+
+```php
+<?php
+
+use ICanBoogie\MessageBus\AssertingMessageBus;
+
+/* @var ICanBoogie\MessageBus\MessageBus $message_bus */
+
+$asserting_message_bus = new AssertingMessageBus($message_bus, function ($message) {
+
+	if (/* some condition */)
+		throw new \LogicException("The message should not be dispatched.");
+
+});
+```
+
+
+
+
+
 ----------
 
 
@@ -228,6 +260,7 @@ The package is continuously tested by [Travis CI](http://about.travis-ci.org/).
 
 
 [documentation]:                       https://icanboogie.org/api/message-bus/master/
+[AssertingMessageBus]:                 https://icanboogie.org/api/message-bus/master/class-ICanBoogie.MessageBus.AssertingMessageBus.html
 [MessageHandlerProvider]:              https://icanboogie.org/api/message-bus/master/class-ICanBoogie.MessageBus.MessageHandlerProvider.html
 [ShouldBePushed]:                      https://icanboogie.org/api/message-bus/master/class-ICanBoogie.MessageBus.ShouldBePushed.html
 [AddCommandBusPass]:                   https://icanboogie.org/api/message-bus/master/class-ICanBoogie.MessageBus.Symfony.AddCommandBusPass.html

lib/AssertingMessageBus.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\MessageBus;
+
+/**
+ * A MessageBus decorator that asserts messages before dispatching them.
+ */
+class AssertingMessageBus implements MessageBus
+{
+	/**
+	 * @var MessageBus
+	 */
+	private $message_bus;
+
+	/**
+	 * @var callable
+	 */
+	private $assertion;
+
+	/**
+	 * @param MessageBus $message_bus
+	 * @param callable $assertion A callable that should throw an exception if the message shouldn't
+	 * be dispatched.
+	 */
+	public function __construct(MessageBus $message_bus, callable $assertion)
+	{
+		$this->message_bus = $message_bus;
+		$this->assertion = $assertion;
+	}
+
+	/**
+	 * @param object $message
+	 *
+	 * @return mixed
+	 */
+	public function dispatch($message)
+	{
+		call_user_func($this->assertion, $message);
+
+		return $this->message_bus->dispatch($message);
+	}
+}

tests/AssertingMessageBusTest.php

@@ -0,0 +1,78 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\MessageBus;
+
+use Prophecy\Argument;
+
+class AssertingMessageBusTest extends \PHPUnit_Framework_TestCase
+{
+	use MockHelpers;
+
+	public function test_should_not_dispatch_message()
+	{
+		$message = (object) [];
+		$exception = new \Exception();
+
+		$message_bus = $this->make_message_bus(
+			function ($message_bus) {
+				$message_bus->dispatch(Argument::any())
+					->shouldNotBeCalled();
+			},
+			function ($actual) use ($message, $exception) {
+				$this->assertSame($message, $actual);
+				throw $exception;
+			}
+		);
+
+		try
+		{
+			$message_bus->dispatch($message);
+		} catch (\Exception $e) {
+			$this->assertSame($exception, $e);
+			return;
+		}
+
+		$this->fail("Expected exception");
+	}
+
+	public function test_should_dispatch_message()
+	{
+		$message = (object) [];
+		$result = uniqid();
+
+		$message_bus = $this->make_message_bus(
+			function ($message_bus) use ($message, $result) {
+				$message_bus->dispatch($message)
+					->shouldBeCalled()->willReturn($result);
+			},
+			function ($actual) use ($message) {
+				$this->assertSame($message, $actual);
+			}
+		);
+
+		$this->assertSame($result, $message_bus->dispatch($message));
+	}
+
+	/**
+	 * @param callable $init_message_bus
+	 * @param callable $assertion
+	 *
+	 * @return AssertingMessageBus
+	 */
+	private function make_message_bus(callable $init_message_bus, callable $assertion)
+	{
+		return new AssertingMessageBus(
+			$this->mock(MessageBus::class, $init_message_bus),
+			$assertion
+		);
+	}
+}