MDL-76571 quiz reports: should not show description items

... or anything else with length = 0. This got broken in MDL-71696.

The only way to fix this kind-of involves and API change to
quiz_report_get_significant_questions. However, it is only changing
the external API of this function back to how it was before the 4.0 release,
and the chnages in 4.0 were never documented, nor, I would guess, intended,
since they just broke things.

mod/quiz/report/grading/report.php

@@ -384,7 +384,7 @@ protected function display_index($includeauto) {
 
             $row[] = $this->questions[$counts->slot]->number;
 
-            $row[] = $PAGE->get_renderer('question', 'bank')->qtype_icon($this->questions[$counts->slot]->type);
+            $row[] = $PAGE->get_renderer('question', 'bank')->qtype_icon($this->questions[$counts->slot]->qtype);
 
             $row[] = format_string($counts->name);
 

mod/quiz/report/overview/report.php

@@ -203,7 +203,6 @@ public function display($quiz, $cm, $course) {
 
             if ($options->slotmarks) {
                 foreach ($questions as $slot => $question) {
-                    // Ignore questions of zero length.
                     $columns[] = 'qsgrade' . $slot;
                     $header = get_string('qbrief', 'quiz', $question->number);
                     if (!$table->is_downloading()) {

mod/quiz/report/overview/tests/behat/basic.feature

@@ -30,28 +30,35 @@ Feature: Basic use of the Grades report
       | activity   | name   | intro              | course | idnumber |
       | quiz       | Quiz 1 | Quiz 1 description | C1     | quiz1    |
     And the following "questions" exist:
-      | questioncategory | qtype       | name  | questiontext    |
-      | Test questions   | truefalse   | TF1   | First question  |
-      | Test questions   | truefalse   | TF2   | Second question |
+      | questioncategory | qtype       | name  | questiontext         |
+      | Test questions   | description | Intro | Welcome to this quiz |
+      | Test questions   | truefalse   | TF1   | First question       |
+      | Test questions   | truefalse   | TF2   | Second question      |
     And quiz "Quiz 1" contains the following questions:
       | question | page | maxmark |
+      | Intro    | 1    |         |
       | TF1      | 1    |         |
       | TF2      | 1    | 3.0     |
     And user "student1" has attempted "Quiz 1" with responses:
       | slot | response |
-      |   1  | True     |
-      |   2  | False    |
+      |   2  | True     |
+      |   3  | False    |
     And user "student2" has attempted "Quiz 1" with responses:
       | slot | response |
-      |   1  | True     |
       |   2  | True     |
+      |   3  | True     |
 
-  @javascript
   Scenario: Using the Grades report
     # Basic check of the Grades report
     When I am on the "Quiz 1" "quiz activity" page logged in as teacher1
     And I navigate to "Results" in current page administration
     Then I should see "Attempts: 2"
+
+    # Verify that the right columns are visible
+    And I should see "Q. 1"
+    And I should see "Q. 2"
+    And I should not see "Q. 3"
+
     # Check student1's grade
     And I should see "25.00" in the "S1 Student1" "table_row"
     # And student2's grade

mod/quiz/report/reportlib.php

@@ -91,36 +91,36 @@ function quiz_has_questions($quizid) {
 /**
  * Get the slots of real questions (not descriptions) in this quiz, in order.
  * @param object $quiz the quiz.
- * @return array of slot => $question object with fields
- *      ->slot, ->id, ->maxmark, ->number, ->length.
+ * @return array of slot => objects with fields
+ *      ->slot, ->id, ->qtype, ->length, ->number, ->maxmark, ->category (for random questions).
  */
 function quiz_report_get_significant_questions($quiz) {
     global $DB;
-    $qsbyslot = [];
     $quizobj = \quiz::create($quiz->id);
     $structure = \mod_quiz\structure::create_for_quiz($quizobj);
     $slots = $structure->get_slots();
+
+    $qsbyslot = [];
+    $number = 1;
     foreach ($slots as $slot) {
+        // Ignore 'questions' of zero length.
+        if ($slot->length == 0) {
+            continue;
+        }
+
         $slotreport = new \stdClass();
         $slotreport->slot = $slot->slot;
         $slotreport->id = $slot->questionid;
         $slotreport->qtype = $slot->qtype;
         $slotreport->length = $slot->length;
+        $slotreport->number = $number;
+        $number += $slot->length;
         $slotreport->maxmark = $slot->maxmark;
-        $slotreport->type = $slot->qtype;
-        if ($slot->qtype === 'random') {
-            $categoryobject = $DB->get_record('question_categories', ['id' => $slot->category]);
-            $slotreport->categoryobject = $categoryobject;
-            $slotreport->category = $slot->category;
-        }
+        $slotreport->category = $slot->category;
+
         $qsbyslot[$slotreport->slot] = $slotreport;
     }
-    ksort($qsbyslot);
-    $number = 1;
-    foreach ($qsbyslot as $question) {
-        $question->number = $number;
-        $number++;
-    }
+
     return $qsbyslot;
 }
 

mod/quiz/report/upgrade.txt

@@ -2,6 +2,13 @@ This files describes API changes for quiz report plugins.
 
 Overview of this plugin type at http://docs.moodle.org/dev/Quiz_reports
 
+=== 4.0.6 ===
+
+There was an ill-advised, never documented, API change in quiz_report_get_significant_questions
+in Moodle 4.0. The API has now been reverted to how it was before 4.0. Hopefully this
+will not cause anyone a problem. (The API revert did not require any changes in any automated tests
+or standard quiz reports.)
+
 === 3.9 ===
 
 * Quiz report plugins defining capabilities used to require an extra string like