Throw exception when handler method is missing

src/Tactician/CommandBus/ExecutingCommandBus.php

@@ -42,6 +42,12 @@ public function execute($command)
         $handler = $this->handlerLocator->getHandlerForCommand($command);
         $methodName = $this->methodNameInflector->inflect($command, $handler);
 
+        // is_callable is used here instead of method_exists, as method_exists
+        // will fail when given a handler that relies on __call.
+        if (!is_callable([$handler, $methodName])) {
+            throw CanNotInvokeHandlerException::onObject($command, "Method '{$methodName}' does not exist on handler");
+        }
+
         return $handler->{$methodName}($command);
     }
 }

tests/Tactician/Tests/CommandBus/ExecutingCommandBusTest.php

@@ -6,7 +6,9 @@
 use Tactician\Handler\MethodNameInflector\MethodNameInflector;
 use Tactician\Handler\Locator\HandlerLocator;
 use Tactician\Tests\Fixtures\Command\TaskCompletedCommand;
+use Tactician\Tests\Fixtures\Handler\DynamicMethodsHandler;
 use Tactician\Tests\Fixtures\Handler\TaskCompletedHandler;
+use stdClass;
 use Mockery;
 
 class ExecutingCommandBusTest extends \PHPUnit_Framework_TestCase
@@ -60,4 +62,64 @@ public function testHandlerIsExecuted()
 
         $this->assertEquals('a-return-value', $this->commandBus->execute($command));
     }
+
+    /**
+     * @expectedException \Tactician\Exception\CanNotInvokeHandlerException
+     */
+    public function testMissingMethodOnHandlerObjectIsDetected()
+    {
+        $command = new TaskCompletedCommand();
+
+        $this->methodNameInflector
+            ->shouldReceive('inflect')
+            ->andReturn('someMethodThatDoesNotExist');
+
+        $this->handlerLocator
+            ->shouldReceive('getHandlerForCommand')
+            ->andReturn(new stdClass);
+
+        $this->assertEquals('a-return-value', $this->commandBus->execute($command));
+    }
+
+    public function testDynamicMethodNamesAreSupported()
+    {
+        $command = new TaskCompletedCommand();
+        $handler = new DynamicMethodsHandler();
+
+        $this->methodNameInflector
+            ->shouldReceive('inflect')
+            ->andReturn('someHandlerMethod');
+
+        $this->handlerLocator
+            ->shouldReceive('getHandlerForCommand')
+            ->andReturn($handler);
+
+        $this->commandBus->execute($command);
+
+        $this->assertEquals(
+            ['someHandlerMethod'],
+            $handler->getMethodsInvoked()
+        );
+    }
+
+    public function testClosuresCanBeInvoked()
+    {
+        $command = new TaskCompletedCommand();
+        $closureWasExecuted = false;
+        $handler = function () use (&$closureWasExecuted) {
+            $closureWasExecuted = true;
+        };
+
+        $this->methodNameInflector
+            ->shouldReceive('inflect')
+            ->andReturn('__invoke');
+
+        $this->handlerLocator
+            ->shouldReceive('getHandlerForCommand')
+            ->andReturn($handler);
+
+        $this->commandBus->execute($command);
+
+        $this->assertTrue($closureWasExecuted);
+    }
 }

tests/Tactician/Tests/Fixtures/Handler/DynamicMethodsHandler.php

@@ -0,0 +1,33 @@
+<?php
+namespace Tactician\Tests\Fixtures\Handler;
+
+/**
+ * Some folks prefer to rely on __call to proxy the incoming commands to
+ * methods, rather than do the routing externally. This test spy can be used to
+ * verify this works correctly.
+ */
+class DynamicMethodsHandler
+{
+    /**
+     * @var string[]
+     */
+    private $methods = [];
+
+    /**
+     * @return string[]
+     */
+    public function getMethodsInvoked()
+    {
+        return $this->methods;
+    }
+
+    /**
+     * @param string $methodName
+     * @param array $args
+     */
+    public function __call($methodName, $args)
+    {
+        $this->methods[] = $methodName;
+    }
+}
+