MDL-84247 questions: rename is_valid_question -> is_qtype_usable

and move it next to is_qtype_installed. This makes the API of the
question_bank class more consistent

mod/quiz/classes/output/edit_renderer.php

@@ -924,7 +924,7 @@ class edit_renderer extends \plugin_renderer_base {
     public function question_preview_icon($quiz, $questiondata, $label = null, $variant = null, $restartversion = null) {
         $question = clone($questiondata);
 
-        if (!\question_bank::is_question_valid($question)) {
+        if (!\question_bank::is_qtype_usable($question->qtype)) {
             return '';
         }
 

mod/quiz/classes/question/bank/preview_action_column.php

@@ -52,7 +52,7 @@ class preview_action_column extends \core_question\local\bank\column_base {
         if (!question_has_capability_on($question, 'use')) {
             return;
         }
-        if (!\question_bank::is_question_valid($question)) {
+        if (!\question_bank::is_qtype_usable($question->qtype)) {
             return;
         }
         $editrenderer = $PAGE->get_renderer('quiz', 'edit');

question/bank/viewquestionname/classes/question_name_idnumber_tags_column.php

@@ -63,7 +63,7 @@ class question_name_idnumber_tags_column extends viewquestionname_column_helper
         echo \html_writer::end_tag('div');
 
         // If the question is invalid, show a warning badge.
-        if (!\question_bank::is_question_valid($question)) {
+        if (!\question_bank::is_qtype_usable($question->qtype)) {
             echo \html_writer::span(get_string('invalidquestiontype', 'question', $question->qtype),
                 'badge bg-danger text-white');
         }

question/classes/local/bank/view.php

@@ -1532,7 +1532,7 @@ class view {
         $attributes = [];
 
         // If the question type is invalid we highlight it red.
-        if (!\question_bank::is_question_valid($question)) {
+        if (!\question_bank::is_qtype_usable($question->qtype)) {
             $rowclasses .= ' table-danger';
         }
         if ($rowclasses) {

question/engine/bank.php

@@ -83,6 +83,23 @@ abstract class question_bank {
         return $plugindir && is_readable($plugindir . '/questiontype.php');
     }
 
+    /**
+     * Check if a given question type is one that is installed and usable.
+     *
+     * Use this before doing things like rendering buttons/options which will only work for
+     * installed question types.
+     *
+     * When loaded through most of the core_question areas, qtype will still be the uninstalled type, e.g. 'mytype',
+     * but when we get to the quiz pages, it will have been converted to 'missingtype'. So we need to check that
+     * as well here.
+     *
+     * @param string $qtypename e.g. 'multichoice'.
+     * @return bool
+     */
+    public static function is_qtype_usable(string $qtypename): bool {
+        return self::is_qtype_installed($qtypename) && $qtypename !== 'missingtype';
+    }
+
     /**
      * Get the question type class for a particular question type.
      * @param string $qtypename the question type name. For example 'multichoice' or 'shortanswer'.
@@ -506,23 +523,6 @@ abstract class question_bank {
         $qtypes = $DB->get_fieldset_sql($sql, $params);
         return $qtypes;
     }
-
-    /**
-     * Check if a given question is valid.
-     * This is used in places where we want to do things like render buttons/options which will only work for
-     * valid, installed question types.
-     *
-     * When loaded through most of the core_question areas, qtype will still be the uninstalled type, e.g. 'mytype',
-     * but when we get to the quiz pages, it will have been converted to 'missingtype'. So we need to check that
-     * as well here.
-     *
-     * @param stdClass $questiondata
-     * @return bool
-     */
-    public static function is_question_valid(stdClass $questiondata): bool {
-        return (self::is_qtype_installed($questiondata->qtype) && $questiondata->qtype !== 'missingtype');
-    }
-
 }