Prevent task overwrite

Author: MrHash

src/Builder/MachineBuilder.php

@@ -3,6 +3,7 @@
 namespace TaskMachine\Builder;
 
 use Shrink0r\PhpSchema\Builder;
+use Shrink0r\PhpSchema\Exception;
 use Shrink0r\PhpSchema\SchemaInterface;
 
 class MachineBuilder extends Builder
@@ -28,4 +29,14 @@ public function build(array $defaults = [])
     {
         return $this->context->build();
     }
+
+    /** @inheritdoc */
+    public function __set($key, $value)
+    {
+        if (parent::__isset($key)) {
+            throw new Exception("Trying to overwrite task '$key'.");
+        }
+
+        parent::__set($key, $value);
+    }
 }

src/Builder/TaskMachineBuilder.php

@@ -77,14 +77,14 @@ public function build(): TaskMachineInterface
     private function mergeMachineTasks(array $schema): array
     {
         foreach ($schema as $name => $config) {
-            $alias = $config['alias'] ?? $name;
-            if (!isset($this->tasks[$alias])) {
-                throw new ConfigError("Task definition for '$alias' not found");
+            $task = $config['task'] ?? $name;
+            if (!isset($this->tasks[$task])) {
+                throw new ConfigError("Task definition for '$task' not found");
             }
 
-            $taskConfig = $this->tasks[$alias];
+            $taskConfig = $this->tasks[$task];
             if ($taskConfig instanceof TaskBuilder) {
-                $result = $this->tasks[$alias]->_build();
+                $result = $this->tasks[$task]->_build();
                 if ($result instanceof Error) {
                     throw new ConfigError('Invalid task configuration given: '.print_r($result->unwrap(), true));
                 }

src/Schema/MachineSchema.php

@@ -84,7 +84,7 @@ private function getTaskSchema(): array
             'type' => 'assoc' ,
             'required' => false,
             'properties' => [
-                'alias' => [ 'type' => 'string', 'required' => false ],
+                'task' => [ 'type' => 'string', 'required' => false ],
                 'handler' => [ 'type' => 'any', 'required' => false ], // @todo callable, object or null
                 'initial' => [ 'type' => 'bool', 'required' => false ],
                 'final' => [ 'type' => 'bool', 'required' => false ],
@@ -103,11 +103,11 @@ private function getTaskSchema(): array
                         ':any_name:' => [ 'type' => 'any' ]
                     ]
                 ],
-                'transition' =>  [
+                'transition' => [
                     'type' => 'any', //@todo array or string
                     'required' => false //@todo required
                 ],
-                'validate' =>  [
+                'validate' => [
                     'type' => 'assoc',
                     'required' => false,
                     'properties' => [