Add GitLab output format support to CheckCommand

Introduced support for the GitLab-specific output format in the Check command and its end-to-end test suite. Modified the condition in the Check command to handle the GitLab format and added a corresponding test case to verify functionality for outputs with no errors.

Author: raffaelecarelle

src/CLI/Command/Check.php

@@ -285,7 +285,7 @@ private function printNoViolationsDetectedMessage(OutputInterface $output, bool
     {
         if (!$onlyErrors) {
             $output->writeln('<info>NO VIOLATIONS DETECTED!</info>');
-        } elseif (Printer::FORMAT_JSON === $format) {
+        } elseif (Printer::FORMAT_JSON === $format || Printer::FORMAT_GITLAB === $format) {
             $output->writeln('<info>[]</info>');
         }
     }

tests/E2E/Cli/CheckCommandTest.php

@@ -221,6 +221,22 @@ public function test_gitlab_format_output(): void
         $this->assertSame(1, $decodedResult[0]['lines']['begin']);
     }
 
+    public function test_gitlab_format_output_no_errors(): void
+    {
+        $configFilePath = __DIR__.'/../_fixtures/configMvcWithoutErrors.php';
+
+        $cmdTester = $this->runCheck($configFilePath, null, null, false, false, false, 'gitlab');
+
+        $this->assertCheckHasSuccess($cmdTester);
+
+        $display = $cmdTester->getDisplay();
+
+        $this->assertJson($display);
+
+        $json = json_decode($display, true);
+        $this->assertCount(0, $json);
+    }
+
     protected function runCheck(
         $configFilePath = null,
         ?bool $stopOnFailure = null,