MDL-73874 Questions: Add new validation for Drag and drop into text

question/type/ddwtos/edit_ddwtos_form.php

@@ -53,4 +53,17 @@ protected function choice_group($mform) {
                 array('size' => 1, 'class' => 'tweakcss'));
         return $grouparray;
     }
+
+    protected function extra_slot_validation(array $slots, array $choices): ?string {
+        foreach ($slots as $slot) {
+            if (count(array_keys($slots, $slot)) > 1) {
+                $choice = $choices[$slot - 1];
+                if (!isset($choice['infinite']) || $choice['infinite'] != 1) {
+                    return get_string('errorlimitedchoice', 'qtype_ddwtos',
+                        html_writer::tag('b', $slot));
+                }
+            }
+        }
+        return null;
+    }
 }

question/type/ddwtos/lang/en/qtype_ddwtos.php

@@ -26,6 +26,7 @@
 $string['answer'] = 'Answer';
 $string['blank'] = 'blank';
 $string['correctansweris'] = 'The correct answer is: {$a}';
+$string['errorlimitedchoice'] = 'Choice [[{$a}]] has been used more than once without being set to "Unlimited". Please recheck this question.';
 $string['infinite'] = 'Unlimited';
 $string['pleaseputananswerineachbox'] = 'Please put an answer in each box.';
 $string['pluginname'] = 'Drag and drop into text';

question/type/ddwtos/tests/behat/add.feature

@@ -39,3 +39,20 @@ Feature: Test creating a drag and drop into text question
     And the following fields match these values:
       | id_shuffleanswers              | 1   |
       | Penalty for each incorrect try | 20% |
+
+  Scenario: Cannot create a drag and drop into text question when making the unsolvable questions
+    When I am on the "Course 1" "core_question > course question bank" page logged in as teacher
+    And I add a "Drag and drop into text" question filling the form with:
+      | Question name                  | Drag and drop into text 001   |
+      | Question text                  | The [[1]] [[2]] on the [[1]]. |
+      | General feedback               | The cat sat on the cat.       |
+      | id_shuffleanswers              | 1                             |
+      | id_choices_0_answer            | cat                           |
+      | id_choices_1_answer            | goes through                  |
+      | id_choices_2_answer            | mat                           |
+      | id_choices_3_answer            | dog                           |
+      | id_choices_4_answer            | table                         |
+      | Penalty for each incorrect try | 20%                           |
+      | Hint 1                         | First hint                    |
+      | Hint 2                         | Second hint                   |
+    Then I should see "Choice [[1]] has been used more than once without being set to \"Unlimited\". Please recheck this question."

question/type/ddwtos/tests/behat/edit.feature

@@ -31,3 +31,14 @@ Feature: Test editing a drag and drop into text questions
       | Question name | Edited question name |
     And I press "id_submitbutton"
     Then I should see "Edited question name"
+
+  Scenario: Cannot update a drag and drop into text question to the unsolvable questions
+    When I am on the "Drag to text" "core_question > edit" page logged in as teacher
+    And I should see "Choice [[1]]"
+    And I should see "Choice [[2]]"
+    And I should see "Choice [[3]]"
+    And I set the following fields to these values:
+      | Question name | Edited question name                   |
+      | Question text | Choice [[1]] Choice [[2]] Choice [[1]] |
+    And I press "id_submitbutton"
+    Then I should see "Choice [[1]] has been used more than once without being set to \"Unlimited\". Please recheck this question."

question/type/gapselect/edit_form_base.php

@@ -281,7 +281,6 @@ private function validate_slots($questiontext, $choices) {
         }
         $slots = $cleanedslots;
 
-        $found = false;
         foreach ($slots as $slot) {
             $found = false;
             foreach ($choices as $key => $choice) {
@@ -299,10 +298,21 @@ private function validate_slots($questiontext, $choices) {
                         html_writer::tag('b', $slot));
             }
         }
-        return false;
+        return $this->extra_slot_validation($slots, $choices) ?? false;
     }
 
     public function qtype() {
         return '';
     }
+
+    /**
+     * Finds more errors in question slots.
+     *
+     * @param array $slots The question text
+     * @param array $choices Question choices
+     * @return string|null Error message or false if no errors
+     */
+    protected function extra_slot_validation(array $slots, array $choices): ?string {
+        return null;
+    }
 }