refactor: cover with unit tests Resource reader, Prompt getter and Tool executor

Author: butschster

.guideline/tests.md

@@ -71,7 +71,6 @@ public function registerPrompt(
         bool $isManual = false,
     ): void {
         $this->referenceProvider->registerPrompt($prompt, $handler, $completionProviders, $isManual);
-
         $this->eventDispatcher?->dispatch(new PromptListChangedEvent());
     }
 

src/Capability/DispatchableRegistry.php

@@ -42,7 +42,7 @@ public function get(GetPromptRequest $request): GetPromptResult
 
         return new GetPromptResult(
             $reference->formatResult(
-                $this->referenceHandler->handle($reference, $request->arguments),
+                $this->referenceHandler->handle($reference, $request->arguments ?? []),
             ),
         );
     }

src/Capability/Prompt/DefaultPromptGetter.php

@@ -162,7 +162,7 @@ private function compileTemplate(): void
      * - array: Converted to JSON if MIME type is application/json or contains 'json'
      *          For other MIME types, will try to convert to JSON with a warning
      */
-    protected function formatResult(mixed $readResult, string $uri, ?string $mimeType = null): array
+    public function formatResult(mixed $readResult, string $uri, ?string $mimeType = null): array
     {
         if ($readResult instanceof ResourceContents) {
             return [$readResult];