MDL-83272 qbank_managecategories: Fix exclusion of current category

The "currentcat" parameter contains the categoryid, but is being
compared to a string like "contextid,categoryid" so was not being
matched correctly to exclude the current category from the list of
options.

question/bank/managecategories/category.php

@@ -67,7 +67,7 @@ if ($todelete) {
     if ($questionstomove) {
         $categorycontext = context::instance_by_id($category->contextid);
         $moveform = new question_move_form($thispageurl,
-            ['contexts' => [$categorycontext], 'currentcat' => $todelete]);
+            ['contexts' => [$categorycontext], 'currentcat' => "$todelete"]);
         if ($moveform->is_cancelled()) {
             $thispageurl->remove_all_params();
             if (!is_null($cmid)) {

question/bank/managecategories/classes/helper.php

@@ -393,7 +393,7 @@ class helper {
             foreach ($categories as $category) {
                 if ($category->contextid == $contextid) {
                     $cid = $category->id;
-                    if ($currentcat != $cid || $currentcat == 0) {
+                    if ("{$currentcat},{$contextid}" != $cid || $currentcat == 0) {
                         $a = new \stdClass();
                         $a->name = format_string(
                             $category->indentedname,

question/bank/managecategories/tests/helper_test.php

@@ -296,6 +296,40 @@ final class helper_test extends manage_category_test_base {
         }
     }
 
+    /**
+     * Test that question_category_options function does not include the current category.
+     *
+     * @covers ::question_category_options
+     */
+    public function test_question_category_options_exclude_current(): void {
+        $this->setAdminUser();
+        $this->resetAfterTest();
+
+        // Create categories.
+        $quiz = $this->create_quiz();
+        $qcategory1 = $this->create_question_category_for_a_quiz($quiz);
+        $qcategory2 = $this->create_question_category_for_a_quiz($quiz, ['parent' => $qcategory1->id]);
+        $qcategory3 = $this->create_question_category_for_a_quiz($quiz);
+
+        $contexts = new \core_question\local\bank\question_edit_contexts(\context_module::instance($quiz->cmid));
+
+        $categorycontexts = helper::question_category_options($contexts->having_cap('moodle/question:add'));
+        // We get all categories without the currentcat parameter.
+        $categorycontext = $categorycontexts['Quiz: ' . $quiz->name];
+        $this->assertCount(3, $categorycontext);
+
+        // The currentcat category is excluded.
+        $newcategorycontexts = helper::question_category_options(
+            $contexts->having_cap('moodle/question:add'),
+            currentcat: $qcategory2->id,
+        );
+        $newcategorycontext = $newcategorycontexts['Quiz: ' . $quiz->name];
+        $this->assertCount(2, $newcategorycontext);
+        $this->assertContains($qcategory1->name, $newcategorycontext);
+        $this->assertNotContains($qcategory2->name, $newcategorycontext);
+        $this->assertContains($qcategory3->name, $newcategorycontext);
+    }
+
     /**
      * Test that get_categories_for_contexts function returns the correct question count number.
      *