validate input for importContacts method and add corresponding tests

Author: gaalferov

src/Api/General/Contact.php

@@ -9,6 +9,7 @@
 use Mailtrap\DTO\Request\Contact\CreateContact;
 use Mailtrap\DTO\Request\Contact\ImportContact;
 use Mailtrap\DTO\Request\Contact\UpdateContact;
+use Mailtrap\Exception\InvalidArgumentException;
 use Psr\Http\Message\ResponseInterface;
 
 /**
@@ -255,10 +256,23 @@ public function deleteContactField(int $fieldId): ResponseInterface
      */
     public function importContacts(array $contacts): ResponseInterface
     {
+
         return $this->handleResponse(
             $this->httpPost(
                 path: $this->getBasePath() . '/imports',
-                body: ['contacts' => array_map(fn(ImportContact $contact) => $contact->toArray(), $contacts)]
+                body: [
+                        'contacts' => array_map(
+                            function ($contact): array {
+                                if (!$contact instanceof ImportContact) {
+                                    throw new InvalidArgumentException(
+                                        'Each contact must be an instance of ImportContact.'
+                                    );
+                                }
+                                return $contact->toArray();
+                            },
+                            $contacts
+                        )
+                    ]
             )
         );
     }

tests/Api/General/ContactTest.php

@@ -8,6 +8,7 @@
 use Mailtrap\DTO\Request\Contact\UpdateContact;
 use Mailtrap\DTO\Request\Contact\ImportContact;
 use Mailtrap\Exception\HttpClientException;
+use Mailtrap\Exception\InvalidArgumentException;
 use Mailtrap\Tests\MailtrapTestCase;
 use Nyholm\Psr7\Response;
 use Mailtrap\Helper\ResponseHelper;
@@ -626,6 +627,32 @@ public function testImportContactsValidationError(): void
         $this->contact->importContacts($contacts);
     }
 
+    public function testImportContactsThrowsExceptionForInvalidInput(): void
+    {
+        $contacts = [
+            new ImportContact(
+                email: '[email protected]',
+                fields: ['first_name' => 'John'],
+                listIdsIncluded: [1],
+                listIdsExcluded: []
+            ),
+            // Invalid input
+            new UpdateContact(
+                email: '[email protected]',
+                fields: ['first_name' => 'John'],
+                listIdsIncluded: [1],
+                listIdsExcluded: []
+            ),
+        ];
+
+        $this->contact->expects($this->never())->method('httpPost');
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Each contact must be an instance of ImportContact.');
+
+        $this->contact->importContacts($contacts);
+    }
+
     private function getExpectedContactFields(): array
     {
         return [