Ensured required config options cannot be left empty

module/Installer/src/Config/Plugin/ApplicationConfigCustomizer.php

@@ -19,20 +19,14 @@ class ApplicationConfigCustomizer implements ConfigCustomizerInterface
             return;
         }
 
-        $validator = function ($value) {
-            return $value;
-        };
         $appConfig->setApp([
             'SECRET' => $io->ask(
-                'Define a secret string that will be used to sign API tokens (leave empty to autogenerate one)',
+                'Define a secret string that will be used to sign API tokens (leave empty to autogenerate one) '
-                null,
+                . '<fg=red>[DEPRECATED. TO BE REMOVED]</>'
-                $validator
             ) ?: $this->generateRandomString(32),
             'DISABLE_TRACK_PARAM' => $io->ask(
                 'Provide a parameter name that you will be able to use to disable tracking on specific request to '
-                . 'short URLs (leave empty and this feature won\'t be enabled)',
+                . 'short URLs (leave empty and this feature won\'t be enabled)'
-                null,
-                $validator
             ),
         ]);
     }

module/Installer/src/Config/Plugin/DatabaseConfigCustomizer.php

@@ -4,12 +4,15 @@ declare(strict_types=1);
 namespace Shlinkio\Shlink\Installer\Config\Plugin;
 
 use Shlinkio\Shlink\Installer\Model\CustomizableAppConfig;
+use Shlinkio\Shlink\Installer\Util\AskUtilsTrait;
 use Symfony\Component\Console\Style\SymfonyStyle;
 use Symfony\Component\Filesystem\Exception\IOException;
 use Symfony\Component\Filesystem\Filesystem;
 
 class DatabaseConfigCustomizer implements ConfigCustomizerInterface
 {
+    use AskUtilsTrait;
+
     private const DATABASE_DRIVERS = [
         'MySQL' => 'pdo_mysql',
         'PostgreSQL' => 'pdo_pgsql',
@@ -59,8 +62,8 @@ class DatabaseConfigCustomizer implements ConfigCustomizerInterface
         // Ask for connection params if database is not SQLite
         if ($params['DRIVER'] !== self::DATABASE_DRIVERS['SQLite']) {
             $params['NAME'] = $io->ask('Database name', 'shlink');
-            $params['USER'] = $io->ask('Database username');
+            $params['USER'] = $this->askRequired($io, 'username', 'Database username');
-            $params['PASSWORD'] = $io->ask('Database password');
+            $params['PASSWORD'] = $this->askRequired($io, 'password', 'Database password');
             $params['HOST'] = $io->ask('Database host', 'localhost');
             $params['PORT'] = $io->ask('Database port', $this->getDefaultDbPort($params['DRIVER']));
         }

module/Installer/src/Config/Plugin/LanguageConfigCustomizer.php

@@ -19,12 +19,12 @@ class LanguageConfigCustomizer implements ConfigCustomizerInterface
         }
 
         $appConfig->setLanguage([
-            'DEFAULT' => $this->chooseLanguage('Select default language for the application in general', $io),
+            'DEFAULT' => $this->chooseLanguage($io, 'Select default language for the application in general'),
-            'CLI' => $this->chooseLanguage('Select default language for CLI executions', $io),
+            'CLI' => $this->chooseLanguage($io, 'Select default language for CLI executions'),
         ]);
     }
 
-    private function chooseLanguage(string $message, SymfonyStyle $io): string
+    private function chooseLanguage(SymfonyStyle $io, string $message): string
     {
         return $io->choice($message, self::SUPPORTED_LANGUAGES, self::SUPPORTED_LANGUAGES[0]);
     }

module/Installer/src/Config/Plugin/UrlShortenerConfigCustomizer.php

@@ -5,11 +5,14 @@ namespace Shlinkio\Shlink\Installer\Config\Plugin;
 
 use Shlinkio\Shlink\Core\Service\UrlShortener;
 use Shlinkio\Shlink\Installer\Model\CustomizableAppConfig;
+use Shlinkio\Shlink\Installer\Util\AskUtilsTrait;
 use Symfony\Component\Console\Style\SymfonyStyle;
 use function str_shuffle;
 
 class UrlShortenerConfigCustomizer implements ConfigCustomizerInterface
 {
+    use AskUtilsTrait;
+
     public function process(SymfonyStyle $io, CustomizableAppConfig $appConfig): void
     {
         $io->title('URL SHORTENER');
@@ -25,14 +28,9 @@ class UrlShortenerConfigCustomizer implements ConfigCustomizerInterface
                 ['http', 'https'],
                 'http'
             ),
-            'HOSTNAME' => $io->ask('Hostname for generated URLs'),
+            'HOSTNAME' => $this->askRequired($io, 'hostname', 'Hostname for generated URLs'),
-            'CHARS' => $io->ask(
+            'CHARS' => $io->ask('Character set for generated short codes (leave empty to autogenerate one)')
-                'Character set for generated short codes (leave empty to autogenerate one)',
+                ?: str_shuffle(UrlShortener::DEFAULT_CHARS),
-                null,
-                function ($value) {
-                    return $value;
-                }
-            ) ?: str_shuffle(UrlShortener::DEFAULT_CHARS),
             'VALIDATE_URL' => $io->confirm('Do you want to validate long urls by 200 HTTP status code on response'),
         ]);
     }

module/Installer/src/Exception/ExceptionInterface.php

@@ -0,0 +1,10 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Installer\Exception;
+
+use Throwable;
+
+interface ExceptionInterface extends Throwable
+{
+}

module/Installer/src/Exception/MissingRequiredOptionException.php

@@ -0,0 +1,15 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Installer\Exception;
+
+use RuntimeException;
+use function sprintf;
+
+class MissingRequiredOptionException extends RuntimeException implements ExceptionInterface
+{
+    public static function fromOption(string $optionName): self
+    {
+        return new self(sprintf('The "%s" is required and can\'t be empty', $optionName));
+    }
+}

module/Installer/src/Util/AskUtilsTrait.php

@@ -0,0 +1,22 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Installer\Util;
+
+use Shlinkio\Shlink\Installer\Exception\MissingRequiredOptionException;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+trait AskUtilsTrait
+{
+    /**
+     * @return mixed
+     */
+    private function askRequired(SymfonyStyle $io, string $optionName, string $question)
+    {
+        return $io->ask($question, null, function ($value) use ($optionName) {
+            if (empty($value)) {
+                throw MissingRequiredOptionException::fromOption($optionName);
+            };
+        });
+    }
+}

module/Installer/test/Exception/MissingRequiredOptionExceptionTest.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace ShlinkioTest\Shlink\Installer\Exception;
+
+use Shlinkio\Shlink\Installer\Exception\MissingRequiredOptionException;
+use PHPUnit\Framework\TestCase;
+
+class MissingRequiredOptionExceptionTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function fromOptionsGeneratesExpectedMessage()
+    {
+        $e = MissingRequiredOptionException::fromOption('foo');
+        $this->assertEquals('The "foo" is required and can\'t be empty', $e->getMessage());
+    }
+}