MDL-74752 qtype_match: implement regrading hooks

As much as they can be before MDL-5560 is addressed.

question/type/match/lang/en/qtype_match.php

@@ -33,8 +33,6 @@
 $string['nomatchinganswerforq'] = 'You must specify an answer for this question.';
 $string['notenoughqsandas'] = 'You must supply at least {$a->q} questions and {$a->a} answers.';
 $string['notenoughquestions'] = 'You must supply at least {$a} question and answer pairs.';
-$string['shuffle'] = 'Shuffle';
-$string['shuffle_help'] = 'If enabled, the order of the questions is randomly shuffled for each attempt, provided that "Shuffle within questions" in the activity settings is also enabled. In a matching question, only the questions are affected by this parameter. The answer choices will always be shuffled.';
 $string['pleaseananswerallparts'] = 'Please answer all parts of the question.';
 $string['pluginname'] = 'Matching';
 $string['pluginname_help'] = 'Matching questions require the respondent to correctly match a list of names or statements (questions) to another list of names or statements (answers).';
@@ -46,3 +44,7 @@
 $string['privacy:preference:defaultmark'] = 'The default mark set for a given question.';
 $string['privacy:preference:penalty'] = 'The penalty for each incorrect try when questions are run using the \'Interactive with multiple tries\' or \'Adaptive mode\' behaviour.';
 $string['privacy:preference:shuffleanswers'] = 'Whether the answers should be automatically shuffled.';
+$string['regradeissuenumchoiceschanged'] = 'The number of choices has changed.';
+$string['regradeissuenumstemschanged'] = 'The number of sub-questions has changed.';
+$string['shuffle'] = 'Shuffle';
+$string['shuffle_help'] = 'If enabled, the order of the questions is randomly shuffled for each attempt, provided that "Shuffle within questions" in the activity settings is also enabled. In a matching question, only the questions are affected by this parameter. The answer choices will always be shuffled.';

question/type/match/question.php

@@ -107,6 +107,23 @@ protected function set_choiceorder($choiceorder) {
         }
     }
 
+    public function validate_can_regrade_with_other_version(question_definition $otherversion): ?string {
+        $basemessage = parent::validate_can_regrade_with_other_version($otherversion);
+        if ($basemessage) {
+            return $basemessage;
+        }
+
+        if (count($this->stems) != count($otherversion->stems)) {
+            return get_string('regradeissuenumstemschanged', 'qtype_match');
+        }
+
+        if (count($this->choices) != count($otherversion->choices)) {
+            return get_string('regradeissuenumchoiceschanged', 'qtype_match');
+        }
+
+        return null;
+    }
+
     public function get_question_summary() {
         $question = $this->html_to_text($this->questiontext, $this->questiontextformat);
         $stems = array();

question/type/match/tests/question_test.php

@@ -33,6 +33,7 @@
  * @package   qtype_match
  * @copyright 2009 The Open University
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @covers \qtype_match_question
  */
 class question_test extends \advanced_testcase {
 
@@ -244,4 +245,32 @@ public function test_get_question_definition_for_external_rendering() {
         $options = $question->get_question_definition_for_external_rendering($qa, $displayoptions);
         $this->assertEquals(1, $options['shufflestems']);
     }
+
+    public function test_validate_can_regrade_with_other_version_ok() {
+        $m = \test_question_maker::make_question('match');
+
+        $newm = clone($m);
+
+        $this->assertNull($newm->validate_can_regrade_with_other_version($m));
+    }
+
+    public function test_validate_can_regrade_with_other_version_bad_stems() {
+        $m = \test_question_maker::make_question('match');
+
+        $newm = clone($m);
+        unset($newm->stems[4]);
+
+        $this->assertEquals(get_string('regradeissuenumstemschanged', 'qtype_match'),
+                $newm->validate_can_regrade_with_other_version($m));
+    }
+
+    public function test_validate_can_regrade_with_other_version_bad_choices() {
+        $m = \test_question_maker::make_question('match');
+
+        $newm = clone($m);
+        unset($newm->choices[3]);
+
+        $this->assertEquals(get_string('regradeissuenumchoiceschanged', 'qtype_match'),
+                $newm->validate_can_regrade_with_other_version($m));
+    }
 }