fix: empty tool calls (#430)

Author: sixlive

src/ValueObjects/ToolCall.php

@@ -25,6 +25,10 @@ public function __construct(
     public function arguments(): array
     {
         if (is_string($this->arguments)) {
+            if ($this->arguments === '' || $this->arguments === '0') {
+                return [];
+            }
+
             /** @var string $arguments */
             $arguments = $this->arguments;
 

tests/ValueObjects/ToolCallTest.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+use Prism\Prism\ValueObjects\ToolCall;
+
+it('handles empty string arguments correctly', function (): void {
+    $toolCall = new ToolCall(
+        id: 'test-id',
+        name: 'test-tool',
+        arguments: ''
+    );
+
+    expect($toolCall->arguments())->toBe([]);
+});
+
+it('handles null arguments correctly', function (): void {
+    $toolCall = new ToolCall(
+        id: 'test-id',
+        name: 'test-tool',
+        arguments: []
+    );
+
+    expect($toolCall->arguments())->toBe([]);
+});
+
+it('handles valid JSON string arguments correctly', function (): void {
+    $toolCall = new ToolCall(
+        id: 'test-id',
+        name: 'test-tool',
+        arguments: '{"param1": "value1", "param2": 42}'
+    );
+
+    expect($toolCall->arguments())->toBe([
+        'param1' => 'value1',
+        'param2' => 42,
+    ]);
+});
+
+it('handles array arguments correctly', function (): void {
+    $arguments = ['param1' => 'value1', 'param2' => 42];
+
+    $toolCall = new ToolCall(
+        id: 'test-id',
+        name: 'test-tool',
+        arguments: $arguments
+    );
+
+    expect($toolCall->arguments())->toBe($arguments);
+});
+
+it('throws exception for malformed JSON string arguments', function (): void {
+    $toolCall = new ToolCall(
+        id: 'test-id',
+        name: 'test-tool',
+        arguments: '{"invalid json"'
+    );
+
+    expect(fn (): array => $toolCall->arguments())->toThrow(JsonException::class);
+});