Fix Moodle Code Checker errors and warnings

filter.php

@@ -133,7 +133,7 @@ public function filter_stage_string(string $text, array $options): string {
      * @param array $options The filter options.
      * @return string The filtered text for this multilang block.
      */
-    public function filter($text, array $options = array()) {
+    public function filter($text, array $options = []) {
 
         if (!is_string($text) || empty($text)) {
             // Non-string data can not be filtered anyway.
@@ -146,7 +146,7 @@ public function filter($text, array $options = array()) {
         }
 
         if (!isset(self::$parentcache)) {
-            self::$parentcache['other'] = array();
+            self::$parentcache['other'] = [];
         }
 
         $this->replacementdone = false;

tests/actual_test_cases.php

@@ -165,7 +165,7 @@ function multilang2_actual_test_cases(): array {
             '{mlang other}Hello!{mlang}{mlang es,es_mx}¡Hola!{mlang}
              This text is common for all languages because it is outside of all lang blocks.
              {mlang other}Bye!{mlang}{mlang it}Ciao!{mlang}',
-            'es_mx', ['es_mx' => 'es']
+            'es_mx', ['es_mx' => 'es'],
         ],
         [
             '

tests/filter_test.php

@@ -75,7 +75,7 @@ protected function setup_parent_language(string $child, string $parent): void {
     /**
      * Data provider for multi-language filtering tests.
      */
-    public function multilang2_test_cases(): array {
+    public static function multilang2_test_cases(): array {
         require_once(dirname(__FILE__) . '/actual_test_cases.php');
         return multilang2_actual_test_cases();
     }
@@ -98,7 +98,7 @@ public function test_filtering($expectedoutput, $input, $targetlang, $parentlang
             $this->setup_parent_language($child, $parent);
         }
 
-        $filtered = format_text($input, FORMAT_HTML, array('context' => \context_system::instance()));
+        $filtered = format_text($input, FORMAT_HTML, ['context' => \context_system::instance()]);
         $this->assertEquals($expectedoutput, $filtered);
     }