more tests, more cleanup

lang/en/qtype_formulas.php

@@ -285,6 +285,7 @@ functions and operators is given in the documentation.
 
 
 
+$string['error_model_answer_no_content'] = 'Invalid answer: the model answer contains no evaluable symbols.';
 $string['error_string_for_algebraic_formula'] = 'Invalid answer format: the answer type "algebraic formula" expects one single string wrapped in quotes or a list of strings, each wrapped in quotes.';
 $string['error_number_for_numeric_answertypes'] = 'Invalid answer format: this answer type expects one number or a list of numbers.';
 $string['error_in_answer'] = 'error in answer #{$a->answerno}: {$a->message}';

question.php

@@ -1302,6 +1302,11 @@ public function get_evaluated_answers(): array {
      */
     private static function wrap_algebraic_formulas_in_quotes(array $formulas): array {
         foreach ($formulas as &$formula) {
+            // If the formula is aready wrapped in quotes (e. g. after an earlier call to this
+            // function), there is nothing to do.
+            if (preg_match('/^\"[^\"]+\"$/', $formula)) {
+                continue;
+            }
             $formula = '"' . $formula . '"';
         }
         // In case we later write to $formula, this would alter the last entry of the $formulas

questiontype.php

@@ -1070,6 +1070,12 @@ public function check_variables_and_expressions(object $data, array $parts): obj
                 // If (and only if) the answer is algebraic, the answer parser should
                 // interpret ^ as **.
                 $answerparser = new answer_parser($part->answer, $knownvars, $isalgebraic);
+                // If the user enters a comment sign in the model answer, it is not technically empty,
+                // but it will be parsed as an empty expression. We catch this here and make use of
+                // the catch block to pass an error message.
+                if (empty($answerparser->get_statements())) {
+                    throw new Exception(get_string('error_model_answer_no_content', 'qtype_formulas'));
+                }
                 $modelanswers = $partevaluator->evaluate($answerparser->get_statements())[0];
             } catch (Exception $e) {
                 // If the answer type is algebraic, the model answer field must contain one string (with quotes)

tests/behat/criterion.feature

@@ -69,10 +69,7 @@ Feature: Test setting the grading criterion in different modes
       | correctness[0] |       |
     And I press "id_submitbutton"
     And I wait until the page is ready
-    # FIXME: with invalid criterion and only one part, might give error "At least one answer is required."
-    # even though an answer is there
     Then I should see "The grading criterion must not be empty."
-    # Then I should see "The grading criterion must be evaluated to a single number."
     And the following fields match these values:
       | correctness_simple_mode[0] |  |
     And the "Simplified mode" "checkbox" should be enabled

tests/parser_test.php

@@ -158,19 +158,6 @@ public function test_basic_operations() {
         //print_r($output);
     }
 
-    public function test_parse_list() {
-        // FIXME - TODO --> implement new test for lists
-        //$input = '[1, 2, 3]';
-        //$input = '[1, "a", 3]';
-        //$input = '[1, ["x", "y"], 3]';
-        //$input = '[[1,2]]';
-        $input = 'a = [1, ["x", "y"], [3, 4], 5, [[1,2]],6]';
-        $input = '-123.541e-13; 4';
-
-        $parser = new answer_parser($input);
-        // print_r($parser->statements);
-    }
-
     /**
      * @dataProvider provide_sets
      */

tests/questiontype_test.php

@@ -274,6 +274,10 @@ public function provide_single_part_data_for_form_validation(): array {
                     'subqtext' => [0 => ['text' => '{_0} and {_0}']],
                 ]
             ],
+            [
+                ['answer[0]' => get_string('error_model_answer_no_content', 'qtype_formulas')],
+                ['answer' => [0 => '#']],
+            ],
             [
                 ['globalunitpenalty' => get_string('error_unitpenalty', 'qtype_formulas')],
                 ['globalunitpenalty' => 2]