From 0aa433a054d9dcb7838f458dab098ea0bd947f79 Mon Sep 17 00:00:00 2001
From: Tim Hunt <T.J.Hunt@open.ac.uk>
Date: Fri, 9 Mar 2012 18:45:54 +0000
Subject: [PATCH] MDL-31981 shortanswer qtype does not handle \* in correct
 response.

---
 question/type/shortanswer/question.php        | 22 ++++++++++++++++++
 question/type/shortanswer/renderer.php        |  3 ++-
 .../type/shortanswer/simpletest/helper.php    | 23 ++++++++++++++++++-
 .../shortanswer/simpletest/testquestion.php   |  6 +++++
 4 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/question/type/shortanswer/question.php b/question/type/shortanswer/question.php
index a5408714927..a875c8c1a05 100644
--- a/question/type/shortanswer/question.php
+++ b/question/type/shortanswer/question.php
@@ -101,6 +101,28 @@ class qtype_shortanswer_question extends question_graded_by_strategy
         return preg_match($regexp, trim($string));
     }
 
+    public function get_correct_response() {
+        $response = parent::get_correct_response();
+        if ($response) {
+            $response['answer'] = $this->clean_response($response['answer']);
+        }
+        return $response;
+    }
+
+    public function clean_response($answer) {
+        // Break the string on non-escaped asterisks.
+        $bits = preg_split('/(?<!\\\\)\*/', $answer);
+
+        // Unescape *s in the bits.
+        $cleanbits = array();
+        foreach ($bits as $bit) {
+            $cleanbits[] = str_replace('\*', '*', $bit);
+        }
+
+        // Put it back together with spaces to look nice.
+        return trim(implode(' ', $cleanbits));
+    }
+
     public function check_file_access($qa, $options, $component, $filearea,
             $args, $forcedownload) {
         if ($component == 'question' && $filearea == 'answerfeedback') {
diff --git a/question/type/shortanswer/renderer.php b/question/type/shortanswer/renderer.php
index 501b1bff52e..e7879bfb680 100644
--- a/question/type/shortanswer/renderer.php
+++ b/question/type/shortanswer/renderer.php
@@ -117,6 +117,7 @@ class qtype_shortanswer_renderer extends qtype_renderer {
             return '';
         }
 
-        return get_string('correctansweris', 'qtype_shortanswer', s($answer->answer));
+        return get_string('correctansweris', 'qtype_shortanswer',
+                s($question->clean_response($answer->answer)));
     }
 }
diff --git a/question/type/shortanswer/simpletest/helper.php b/question/type/shortanswer/simpletest/helper.php
index 71a0f409111..533b5802d75 100644
--- a/question/type/shortanswer/simpletest/helper.php
+++ b/question/type/shortanswer/simpletest/helper.php
@@ -34,7 +34,7 @@ defined('MOODLE_INTERNAL') || die();
  */
 class qtype_shortanswer_test_helper extends question_test_helper {
     public function get_test_questions() {
-        return array('frogtoad', 'frogonly');
+        return array('frogtoad', 'frogonly', 'escapedwildcards');
     }
 
     /**
@@ -130,4 +130,25 @@ class qtype_shortanswer_test_helper extends question_test_helper {
 
         return $qdata;
     }
+
+    /**
+     * Makes a shortanswer question with just the correct ansewer 'frog', and
+     * no other answer matching.
+     * @return qtype_shortanswer_question
+     */
+    public function make_shortanswer_question_escapedwildcards() {
+        question_bank::load_question_definition_classes('shortanswer');
+        $sa = new qtype_shortanswer_question();
+        test_question_maker::initialise_a_question($sa);
+        $sa->name = 'Question with escaped * in the answer.';
+        $sa->questiontext = 'How to you write x times y in C? __________';
+        $sa->generalfeedback = 'In C, this expression is written x * y.';
+        $sa->usecase = false;
+        $sa->answers = array(
+            13 => new question_answer(13, '*x\*y*', 1.0, 'Well done.', FORMAT_HTML),
+        );
+        $sa->qtype = question_bank::get_qtype('shortanswer');
+
+        return $sa;
+    }
 }
diff --git a/question/type/shortanswer/simpletest/testquestion.php b/question/type/shortanswer/simpletest/testquestion.php
index 4db7d6b4b79..54aa98758a5 100644
--- a/question/type/shortanswer/simpletest/testquestion.php
+++ b/question/type/shortanswer/simpletest/testquestion.php
@@ -145,6 +145,12 @@ class qtype_shortanswer_question_test extends UnitTestCase {
                 $question->get_correct_response());
     }
 
+    public function test_get_correct_response_escapedwildcards() {
+        $question = test_question_maker::make_question('shortanswer', 'escapedwildcards');
+
+        $this->assertEqual(array('answer' => 'x*y'), $question->get_correct_response());
+    }
+
     public function test_get_question_summary() {
         $sa = test_question_maker::make_question('shortanswer');
         $qsummary = $sa->get_question_summary();