MDL-50515 mod_lesson: Can't remove content buttons from content page

mod/lesson/locallib.php

@@ -2740,7 +2740,7 @@ public function update($properties, $context = null, $maxbytes = null) {
                     $this->answers[$i]->timecreated = $this->timecreated;
                 }
 
-                if (!empty($properties->answer_editor[$i])) {
+                if (isset($properties->answer_editor[$i])) {
                     if (is_array($properties->answer_editor[$i])) {
                         // Multichoice and true/false pages have an HTML editor.
                         $this->answers[$i]->answer = $properties->answer_editor[$i]['text'];

mod/lesson/tests/behat/lesson_delete_answers.feature

@@ -0,0 +1,96 @@
+@mod @mod_lesson
+Feature: In a lesson activity, teacher can delete question answers and
+branch table contents
+  In order to modify an existing lesson
+  As a teacher
+  I need to question answers and branch table contents in the lesson
+
+  Background:
+    Given the following "users" exist:
+      | username | firstname | lastname | email |
+      | teacher1 | Teacher | 1 | teacher1@example.com |
+      | student1 | Student | 1 | student1@example.com |
+    And the following "courses" exist:
+      | fullname | shortname | category |
+      | Course 1 | C1 | 0 |
+    And the following "course enrolments" exist:
+      | user | course | role |
+      | teacher1 | C1 | editingteacher |
+      | student1 | C1 | student |
+    And I log in as "teacher1"
+    And I follow "Course 1"
+    And I turn editing mode on
+    And I add a "Lesson" to section "1" and I fill the form with:
+      | Name | Test lesson name |
+      | Description | Test lesson description |
+    And I follow "Test lesson name"
+    And I follow "Add a content page"
+    And I set the following fields to these values:
+      | Page title | First page name |
+      | Page contents | First page contents |
+      | id_answer_editor_0 | Next page |
+      | id_jumpto_0 | Next page |
+      | id_answer_editor_1 | Previous page |
+      | id_jumpto_1 | Previous page |
+    And I press "Save page"
+    And I set the field "qtype" to "Question"
+    And I set the field "Select a question type" to "Numerical"
+    And I press "Add a question page"
+    And I set the following fields to these values:
+      | Page title | Hardest question ever |
+      | Page contents | 1 + 1? |
+      | id_answer_editor_0 | 2 |
+      | id_response_editor_0 | Correct answer |
+      | id_jumpto_0 | End of lesson |
+      | id_score_0 | 1 |
+      | id_answer_editor_1 | 1 |
+      | id_response_editor_1 | Incorrect answer |
+      | id_jumpto_1 | First page name |
+      | id_score_1 | 0 |
+    And I press "Save page"
+    And I follow "Expanded"
+
+  @javascript
+  Scenario: Edit lesson content page
+    Given I click on "//th[normalize-space(.)='First page name']/descendant::a[2]" "xpath_element"
+    When I set the following fields to these values:
+      | id_answer_editor_1 | |
+    And I press "Save page"
+    And I should not see "Previous page"
+    And I log out
+    And I log in as "student1"
+    And I follow "Course 1"
+    And I follow "Test lesson name"
+    And I should see "First page contents"
+    And I should not see "Previous page"
+    And I press "Next page"
+    And I should see "1 + 1?"
+    And I set the following fields to these values:
+      | Your answer | 2 |
+    And I press "Submit"
+    And I should see "Correct answer"
+    And I should not see "Incorrect answer"
+    And I press "Continue"
+    And I should see "Congratulations - end of lesson reached"
+    And I should see "Your score is 1 (out of 1)."
+
+  @javascript
+  Scenario: Edit lesson question page
+    Given I click on "//th[normalize-space(.)='Hardest question ever']/descendant::a[2]" "xpath_element"
+    When I set the following fields to these values:
+      | id_answer_editor_1 | |
+    And I press "Save page"
+    And I should not see "Incorrect answer"
+    And I log out
+    And I log in as "student1"
+    And I follow "Course 1"
+    And I follow "Test lesson name"
+    And I should see "First page contents"
+    And I press "Next page"
+    And I should see "1 + 1?"
+    And I set the following fields to these values:
+      | Your answer | 1 |
+    And I press "Submit"
+    And I should not see "Incorrect answer"
+    And I should see "Congratulations - end of lesson reached"
+    And I should see "Your score is 0 (out of 1)."