Consider null parameters invalid

Parameters passed to validateParameter should always be non-null, and if they're null, an exception is thrown.

src/Database/Concerns/ValidatesDatabaseParameters.php

@@ -50,20 +50,19 @@ trait ValidatesDatabaseParameters
      *
      * By default, only the characters in allowedParameterCharacters() are allowed.
      *
-     * Null parameters are skipped.
-     *
      * @throws InvalidArgumentException
      */
     protected function validateParameter(string|array|null $parameters, string|null $allowedCharacters = null): void
     {
+        if ($parameters === null) {
+            throw new InvalidArgumentException('Parameter cannot be null.');
+        }
+
         $allowedCharacters ??= $this->allowedParameterCharacters();
 
         foreach (Arr::wrap($parameters) as $parameter) {
             if (is_null($parameter)) {
-                // Skip if there's nothing to validate
+                throw new InvalidArgumentException('Parameter cannot be null.');
-                // (e.g. when $tenant->database()->getUsername() of an
-                // improperly created tenant is null and it gets passed).
-                continue;
             }
 
             if (is_numeric($parameter)) {

src/Database/TenantDatabaseManagers/MySQLDatabaseManager.php

@@ -14,7 +14,7 @@ class MySQLDatabaseManager extends TenantDatabaseManager
         $charset = $this->connection()->getConfig('charset');
         $collation = $this->connection()->getConfig('collation');
 
-        $this->validateParameter([$database, $charset, $collation]);
+        $this->validateParameter(array_filter([$database, $charset, $collation], fn ($param) => $param !== null));
 
         // MySQL defaults to the server's charset and collation
         // if charset and collation are not specified.

tests/TenantDatabaseManagerTest.php

@@ -591,6 +591,7 @@ test('database managers validate parameters used in raw sql statements', functio
         $tenantWithInvalidDatabase = Tenant::make([
             'tenancy_db_name' => $invalidDatabaseName,
             'tenancy_db_username' => 'valid_USERNAME',
+            'tenancy_db_password' => 'valid_password',
         ]);
 
         expect(fn () => $manager->createUser($tenantWithInvalidDatabase->database()))
@@ -615,16 +616,14 @@ test('database managers validate parameters used in raw sql statements', functio
         expect(fn () => $manager->createUser($tenantWithValidPassword->database()))
             ->not()->toThrow(InvalidArgumentException::class, 'Forbidden character');
 
-        $tenantWithNullDbParameters = Tenant::make([
+        $tenantWithNullCredentials = Tenant::make([
-            'tenancy_db_name' => null,
+            'tenancy_db_name' => 'valid_db_name',
             'tenancy_db_username' => null,
             'tenancy_db_password' => null,
         ]);
 
-        // validateParameter() doesn't throw InvalidArgumentException if a parameter is null
+        expect(fn () => $manager->createUser($tenantWithNullCredentials->database()))
-        // (an exception will be thrown, but not by validateParameter()).
+            ->toThrow(InvalidArgumentException::class, 'Parameter cannot be null.');
-        expect(fn () => $manager->createUser($tenantWithNullDbParameters->database()))
-            ->not()->toThrow(InvalidArgumentException::class);
     }
 })->with('database_managers');