Throw DuplicateTransitionException on duplicate state transitions i…

…n `StateConfig`

CHANGELOG.md

@@ -9,6 +9,12 @@ See [GitHub releases](https://github.com/mll-lab/laravel-utils/releases).
 
 ## Unreleased
 
+## v8.0.0
+
+### Changed
+
+- Throw `DuplicateTransitionException` on duplicate state transitions in `StateConfig`
+
 ## v7.0.0
 
 ### Added

src/ModelStates/Exceptions/DuplicateTransitionException.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+namespace MLL\LaravelUtils\ModelStates\Exceptions;
+
+final class DuplicateTransitionException extends \Exception
+{
+    public function __construct(string $from, string $to)
+    {
+        parent::__construct("There is already a transition from {$from} to {$to}.");
+    }
+}

src/ModelStates/StateConfig.php

@@ -5,13 +5,14 @@
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Collection as SupportCollection;
 use MLL\LaravelUtils\ModelStates\Exceptions\ClassDoesNotExtendBaseClass;
+use MLL\LaravelUtils\ModelStates\Exceptions\DuplicateTransitionException;
 
 final class StateConfig
 {
     /**
      * @var array<
-     *      class-string<State>,
-     *      array<class-string<State>, class-string<Transition>|null>
+     *   class-string<State>,
+     *   array<class-string<State>, class-string<Transition>|null>,
      * >
      */
     public array $allowedTransitions = [];
@@ -31,24 +32,22 @@ public function allowTransition(string|array $fromOrFroms, string $to, string $t
             return $this;
         }
 
-        // @phpstan-ignore-next-line php-stan is not right here
+        // @phpstan-ignore-next-line PHPStan is not right here
         if (! is_subclass_of($fromOrFroms, State::class)) {
             throw new ClassDoesNotExtendBaseClass($fromOrFroms, State::class);
         }
 
-        // @phpstan-ignore-next-line php-stan is not right here
+        // @phpstan-ignore-next-line PHPStan is not right here
         if (! is_subclass_of($to, State::class)) {
             throw new ClassDoesNotExtendBaseClass($to, State::class);
         }
 
         // There might already be transitions registered for this state
-        $fromTransition = $this->allowedTransitions[$fromOrFroms] ?? [];
-
-        // We just overwrite the transition with what was defined.
-        // We might consider throwing an exception here to catch double configuration.
-        $fromTransition[$to] = $transition;
+        if (isset($this->allowedTransitions[$fromOrFroms][$to])) {
+            throw new DuplicateTransitionException($fromOrFroms, $to);
+        }
 
-        $this->allowedTransitions[$fromOrFroms] = $fromTransition;
+        $this->allowedTransitions[$fromOrFroms][$to] = $transition;
 
         return $this;
     }
@@ -103,7 +102,7 @@ public function possibleNextStates(State $from): SupportCollection
             $next[$stateClass] = new $stateClass();
         }
 
-        // @phpstan-ignore-next-line php-stan is not right here
+        // @phpstan-ignore-next-line PHPStan is not right here
         return new SupportCollection($next);
     }
 

src/ModelStates/StateEnumType.php

@@ -20,7 +20,7 @@ final class StateEnumType extends EnumType
      */
     public function __construct(string $stateClass, ?string $name = null)
     {
-        // @phpstan-ignore-next-line php-stan is not right here
+        // @phpstan-ignore-next-line PHPStan is not right here
         if (! is_subclass_of($stateClass, State::class)) {
             $abstractState = State::class;
             throw new \InvalidArgumentException("Must pass an instance of {$abstractState}, got {$stateClass}.");

tests/ModelStates/StateTest.php

@@ -16,10 +16,12 @@
 use App\ModelStates\Transitions\CustomTransition;
 use Illuminate\Support\Collection as SupportCollection;
 use MLL\LaravelUtils\ModelStates\DefaultTransition;
+use MLL\LaravelUtils\ModelStates\Exceptions\DuplicateTransitionException;
 use MLL\LaravelUtils\ModelStates\Exceptions\TransitionNotAllowed;
 use MLL\LaravelUtils\ModelStates\Exceptions\TransitionNotFound;
 use MLL\LaravelUtils\ModelStates\Exceptions\UnknownStateException;
 use MLL\LaravelUtils\ModelStates\MermaidStateConfigValidator;
+use MLL\LaravelUtils\ModelStates\StateConfig;
 use MLL\LaravelUtils\ModelStates\TransitionDirection;
 use MLL\LaravelUtils\Tests\DBTestCase;
 
@@ -182,6 +184,15 @@ public function testUnknownStateThrowsExceptionsForRetrieval(): void
         $model->state;
     }
 
+    public function testDuplicateTransitionException(): void
+    {
+        $stateConfig = new StateConfig();
+        $stateConfig->allowTransition(StateA::class, StateB::class);
+
+        $this->expectExceptionObject(new DuplicateTransitionException(StateA::class, StateB::class));
+        $stateConfig->allowTransition(StateA::class, StateB::class);
+    }
+
     public function testGenerateMermaidGraph(): void
     {
         $workflowAsMermaidGraph = /** @lang Mermaid */ <<<'MERMAID'