MDL-66633 quiz: allow to create attempts for different users

By adding a new optional param to quiz_prepare_and_start_new_attempt()
it can be used by the surrounding code to create an attempt for anybody
else (different from current $USER)

quiz attempt API should let you create an attempt for a different user

mod/quiz/locallib.php

@@ -2403,22 +2403,29 @@ function quiz_validate_new_attempt(quiz $quizobj, quiz_access_manager $accessman
  *      to force the choice of a particular actual question. Intended for testing purposes only.
  * @param array $forcedvariants slot number => variant. Used for questions with variants,
  *      to force the choice of a particular variant. Intended for testing purposes only.
+ * @param int $userid Specific user id to create an attempt for that user, null for current logged in user
  * @return object the new attempt
  * @since  Moodle 3.1
  */
 function quiz_prepare_and_start_new_attempt(quiz $quizobj, $attemptnumber, $lastattempt,
-        $offlineattempt = false, $forcedrandomquestions = [], $forcedvariants = []) {
+        $offlineattempt = false, $forcedrandomquestions = [], $forcedvariants = [], $userid = null) {
     global $DB, $USER;
 
+    $ispreviewuser = false;
+
     // Delete any previous preview attempts belonging to this user.
-    quiz_delete_previews($quizobj->get_quiz(), $USER->id);
+    if ($userid === null) {
+        $userid = $USER->id;
+        $ispreviewuser = $quizobj->is_preview_user();
+    }
+    quiz_delete_previews($quizobj->get_quiz(), $userid);
 
     $quba = question_engine::make_questions_usage_by_activity('mod_quiz', $quizobj->get_context());
     $quba->set_preferred_behaviour($quizobj->get_quiz()->preferredbehaviour);
 
     // Create the new attempt and initialize the question sessions
     $timenow = time(); // Update time now, in case the server is running really slowly.
-    $attempt = quiz_create_attempt($quizobj, $attemptnumber, $lastattempt, $timenow, $quizobj->is_preview_user());
+    $attempt = quiz_create_attempt($quizobj, $attemptnumber, $lastattempt, $timenow, $ispreviewuser, $userid);
 
     if (!($quizobj->get_quiz()->attemptonlast && $lastattempt)) {
         $attempt = quiz_start_new_attempt($quizobj, $quba, $attempt, $attemptnumber, $timenow,

mod/quiz/tests/attempt_test.php

@@ -311,4 +311,52 @@ public function test_is_participant() {
         $this->assertEquals(true, $quizobj->is_participant($USER->id),
             'Admin is enrolled, suspended and can participate');
     }
+
+    /**
+     * Test quiz_prepare_and_start_new_attempt function
+     */
+    public function test_quiz_prepare_and_start_new_attempt() {
+        $this->resetAfterTest();
+
+        // Create course.
+        $course = $this->getDataGenerator()->create_course();
+        // Create students.
+        $student1 = $this->getDataGenerator()->create_and_enrol($course, 'student');
+        $student2 = $this->getDataGenerator()->create_and_enrol($course, 'student');
+        // Create quiz.
+        $quizgenerator = $this->getDataGenerator()->get_plugin_generator('mod_quiz');
+        $quiz = $quizgenerator->create_instance(['course' => $course->id, 'grade' => 100.0, 'sumgrades' => 2, 'layout' => '1,0']);
+        // Create question and add it to quiz.
+        $questiongenerator = $this->getDataGenerator()->get_plugin_generator('core_question');
+        $cat = $questiongenerator->create_question_category();
+        $question = $questiongenerator->create_question('shortanswer', null, ['category' => $cat->id]);
+        quiz_add_quiz_question($question->id, $quiz, 1);
+
+        $quizobj = quiz::create($quiz->id);
+
+        // Login as student1.
+        $this->setUser($student1);
+        // Create attempt for student1.
+        $attempt = quiz_prepare_and_start_new_attempt($quizobj, 1, null, false, [], []);
+        $this->assertEquals($student1->id, $attempt->userid);
+        $this->assertEquals(0, $attempt->preview);
+
+        // Login as student2.
+        $this->setUser($student2);
+        // Create attempt for student2.
+        $attempt = quiz_prepare_and_start_new_attempt($quizobj, 1, null, false, [], []);
+        $this->assertEquals($student2->id, $attempt->userid);
+        $this->assertEquals(0, $attempt->preview);
+
+        // Login as admin.
+        $this->setAdminUser();
+        // Create attempt for student1.
+        $attempt = quiz_prepare_and_start_new_attempt($quizobj, 2, null, false, [], [], $student1->id);
+        $this->assertEquals($student1->id, $attempt->userid);
+        $this->assertEquals(0, $attempt->preview);
+        // Create attempt for student2.
+        $attempt = quiz_prepare_and_start_new_attempt($quizobj, 2, null, false, [], [], $student2->id);
+        $this->assertEquals($student2->id, $attempt->userid);
+        $this->assertEquals(0, $attempt->preview);
+    }
 }