MDL-63117 mod_book: Check if the module is visible to the user

mod/book/lib.php

@@ -768,6 +768,12 @@ function mod_book_core_calendar_provide_event_action(calendar_event $event,
     }
 
     $cm = get_fast_modinfo($event->courseid, $userid)->instances['book'][$event->instance];
+
+    if (!$cm->uservisible) {
+        // The module is not visible to the user for any reason.
+        return null;
+    }
+
     $context = context_module::instance($cm->id);
 
     if (!has_capability('mod/book:read', $context, $userid)) {

mod/book/tests/lib_test.php

@@ -160,6 +160,34 @@ class mod_book_lib_testcase extends advanced_testcase {
         $this->assertTrue($actionevent->is_actionable());
     }
 
+    public function test_book_core_calendar_provide_event_action_in_hidden_section() {
+        // Create the activity.
+        $course = $this->getDataGenerator()->create_course();
+        $book = $this->getDataGenerator()->create_module('book', array('course' => $course->id));
+
+        // Enrol a student in the course.
+        $student = $this->getDataGenerator()->create_and_enrol($course, 'student');
+
+        // Create a calendar event.
+        $event = $this->create_action_event($course->id, $book->id,
+                \core_completion\api::COMPLETION_EVENT_TYPE_DATE_COMPLETION_EXPECTED);
+
+        // Set sections 0 as hidden.
+        set_section_visible($course->id, 0, 0);
+
+        // Now, log out.
+        $this->setUser();
+
+        // Create an action factory.
+        $factory = new \core_calendar\action_factory();
+
+        // Decorate action event for the student.
+        $actionevent = mod_book_core_calendar_provide_event_action($event, $factory, $student->id);
+
+        // Confirm the event is not shown at all.
+        $this->assertNull($actionevent);
+    }
+
     public function test_book_core_calendar_provide_event_action_for_user() {
         // Create the activity.
         $course = $this->getDataGenerator()->create_course();