feat: allow mocking output interface (#20)

- required for old symfony versions

src/Command.php

@@ -36,7 +36,7 @@ protected function configure(): void
     public function run(InputInterface $input, OutputInterface $output): int
     {
         $this->input = $input;
-        $this->output = new SymfonyStyle($input, $output);
+        $this->output = StyleFactory::create($input, $output);
 
         return parent::run($input, $output);
     }
@@ -86,7 +86,7 @@ protected function arguments(): array
     /**
      * Writes a message to the output and adds a newline at the end.
      */
-    protected function line(string $message, string $style = null, string|int $verbosity = 'normal'): void
+    protected function line(string $message, ?string $style = null, string|int $verbosity = 'normal'): void
     {
         $styled = $style ? "<$style>$message</$style>" : $message;
 
@@ -168,12 +168,12 @@ protected function caution(string|array $message): void
         $this->output->caution($message);
     }
 
-    protected function ask(string $question, string $default = null, callable $validator = null): mixed
+    protected function ask(string $question, ?string $default = null, ?callable $validator = null): mixed
     {
         return $this->output->ask($question, $default, $validator);
     }
 
-    protected function askHidden(string $question, callable $validator = null): mixed
+    protected function askHidden(string $question, ?callable $validator = null): mixed
     {
         return $this->output->askHidden($question, $validator);
     }

src/LegacySymfonyStyle.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symblaze\Console;
+
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\NullOutput;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+/**
+ * Old versions of Symfony do not add return data types to the output interface.
+ * This class is a workaround to allow mocking the output interface in tests.
+ */
+final class LegacySymfonyStyle extends SymfonyStyle
+{
+    public function __construct(InputInterface $input)
+    {
+        parent::__construct($input, new NullOutput());
+    }
+}

src/StyleFactory.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symblaze\Console;
+
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+final class StyleFactory
+{
+    public static function create(InputInterface $input, OutputInterface $output): SymfonyStyle
+    {
+        return is_null($output->getFormatter()) ?
+            new LegacySymfonyStyle($input) :
+            new SymfonyStyle($input, $output);
+    }
+}