add abstract empty command

README.md

@@ -36,7 +36,7 @@ require './vendor/autoload.php';
 
 Commands are DTOs that carry all the information for an action to happen
 
-You can create your own by implementing `Gears\CQRS\Command` or extend from `Gears\CQRS\AbstractCommand` which ensures command immutability and payload is composed only of **scalar values** which is a very interesting capability. AbstractCommand has a protected constructor forcing you to create a custom static named constructors
+You can create your own by implementing `Gears\CQRS\Command` or extend from `Gears\CQRS\AbstractCommand` which ensures command immutability and payload is composed only of **scalar values** which is a very interesting capability. AbstractCommand has a protected constructor forcing you to create custom static named constructors
 
 ```php
 use Gears\CQRS\AbstractCommand;
@@ -57,6 +57,19 @@ class CreateUserCommand extends AbstractCommand
 }
 ```
 
+In case of a command without any payload you could extend `Gears\CQRS\AbstractEmptyCommand`
+
+```php
+use Gears\CQRS\AbstractCommand;
+
+class CreateUserCommand extends AbstractEmptyCommand
+{
+    public static function instance(): self {
+        return new self();
+    }
+}
+```
+
 #### Async commands
 
 Having command assuring all of its payload is composed only of scalar values proves handy when you want to delegate command handling to a message queue system such as RabbitMQ, Gearman or Apache Kafka, serializing/deserializing scalar values is trivial in any format and language
@@ -112,15 +125,15 @@ class CreateUserCommandHandler extends AbstractCommandHandler
 }
 ```
 
-Have a look at [phpgears/dto](https://github.com/phpgears/dto) fo a better understanding of how commands and queries are built and how they hold their payload
+Have a look at [phpgears/dto](https://github.com/phpgears/dto) fo a better understanding of how commands and queries are built out of DTOs and how they hold their payload
 
 ### Buses
 
 Only `Gears\CQRS\CommandBus` and `Gears\CQRS\QueryBus` interfaces are provided, you can easily use any of the good bus libraries available out there by simply adding an adapter layer
 
 #### Implementations
 
-Available CQRS buses implementations
+CQRS buses implementations currently available
 
 * [phpgears/cqrs-tactician](https://github.com/phpgears/cqrs-tactician) uses League's Tactician
 

src/AbstractEmptyCommand.php

@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * cqrs (https://github.com/phpgears/cqrs).
+ * CQRS base.
+ *
+ * @license MIT
+ * @link https://github.com/phpgears/cqrs
+ * @author Julián Gutiérrez <juliangut@gmail.com>
+ */
+
+declare(strict_types=1);
+
+namespace Gears\CQRS;
+
+use Gears\DTO\ScalarPayloadBehaviour;
+use Gears\Immutability\ImmutabilityBehaviour;
+
+/**
+ * Abstract empty immutable event.
+ */
+abstract class AbstractEmptyCommand implements Command
+{
+    use ImmutabilityBehaviour, ScalarPayloadBehaviour {
+        ScalarPayloadBehaviour::__call insteadof ImmutabilityBehaviour;
+    }
+
+    /**
+     * AbstractEmptyCommand constructor.
+     */
+    final protected function __construct()
+    {
+        $this->checkImmutability();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    final public static function reconstitute(array $parameters)
+    {
+        return new static();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return string[]
+     */
+    final protected function getAllowedInterfaces(): array
+    {
+        return [Command::class];
+    }
+}

tests/CQRS/AbstractCommandHandlerTest.php

@@ -13,43 +13,42 @@
 
 namespace Gears\CQRS\Tests;
 
-use Gears\CQRS\AbstractCommand;
 use Gears\CQRS\Tests\Stub\AbstractCommandHandlerStub;
 use Gears\CQRS\Tests\Stub\AbstractCommandStub;
+use Gears\CQRS\Tests\Stub\AbstractEmptyCommandStub;
 use PHPUnit\Framework\TestCase;
 
 /**
  * Abstract command handler test.
  */
 class AbstractCommandHandlerTest extends TestCase
 {
-    public function testHandling(): void
-    {
-        $handler = new AbstractCommandHandlerStub();
-        $handler->handle(AbstractCommandStub::instance());
-
-        $this->assertTrue(true);
-    }
-
     /**
      * @expectedException \Gears\CQRS\Exception\InvalidCommandException
      * @expectedExceptionMessageRegExp /Command must be a .+\\AbstractCommandStub, .+ given/
      */
     public function testInvalidCommandType(): void
     {
-        /** @var AbstractCommand $command */
-        $command = $this->getMockBuilder(AbstractCommand::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        $handler = new AbstractCommandHandlerStub();
+        $handler->handle(AbstractEmptyCommandStub::instance());
+    }
 
+    public function testHandling(): void
+    {
         $handler = new AbstractCommandHandlerStub();
-        $handler->handle($command);
+        $handler->handle(AbstractCommandStub::instance());
+
+        $this->assertTrue(true);
     }
 
     public function testReconstitute(): void
     {
         $command = AbstractCommandStub::reconstitute(['parameter' => 'one']);
 
         $this->assertTrue($command->has('parameter'));
+
+        $emptyCommand = AbstractEmptyCommandStub::reconstitute(['parameter' => 'one']);
+
+        $this->assertFalse($emptyCommand->has('parameter'));
     }
 }

tests/CQRS/Stub/AbstractEmptyCommandHandlerStub.php

@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * cqrs (https://github.com/phpgears/cqrs).
+ * CQRS base.
+ *
+ * @license MIT
+ * @link https://github.com/phpgears/cqrs
+ * @author Julián Gutiérrez <juliangut@gmail.com>
+ */
+
+declare(strict_types=1);
+
+namespace Gears\CQRS\Tests\Stub;
+
+use Gears\CQRS\AbstractCommandHandler;
+use Gears\CQRS\Command;
+
+/**
+ * Abstract command handler stub class.
+ */
+class AbstractEmptyCommandHandlerStub extends AbstractCommandHandler
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function getSupportedCommandType(): string
+    {
+        return AbstractEmptyCommandStub::class;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function handleCommand(Command $command): void
+    {
+    }
+}

tests/CQRS/Stub/AbstractEmptyCommandStub.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * cqrs (https://github.com/phpgears/cqrs).
+ * CQRS base.
+ *
+ * @license MIT
+ * @link https://github.com/phpgears/cqrs
+ * @author Julián Gutiérrez <juliangut@gmail.com>
+ */
+
+declare(strict_types=1);
+
+namespace Gears\CQRS\Tests\Stub;
+
+use Gears\CQRS\AbstractEmptyCommand;
+
+/**
+ * Abstract empty command stub class.
+ */
+class AbstractEmptyCommandStub extends AbstractEmptyCommand
+{
+    /**
+     * Instantiate command.
+     *
+     * @return self
+     */
+    public static function instance(): self
+    {
+        return new self();
+    }
+}