MDL-73339 glossary_random: Add block only if main feature is enabled

The Random glossary entry block should be added only if the glossary
module is enabled.

blocks/glossary_random/block_glossary_random.php

@@ -270,5 +270,15 @@ public function get_config_for_external() {
             'plugin' => new stdClass(),
         ];
     }
-}
 
+    /**
+     * This block shouldn't be added to a page if the glossary module is disabled.
+     *
+     * @param moodle_page $page
+     * @return bool
+     */
+    public function can_block_be_added(moodle_page $page): bool {
+        $pluginclass = \core_plugin_manager::resolve_plugininfo_class('mod');
+        return $pluginclass::get_enabled_plugin('glossary');
+    }
+}

blocks/glossary_random/tests/behat/glossary_random_addblock.feature

@@ -0,0 +1,23 @@
+@block @block_glossary_random @javascript @addablocklink
+Feature: Add the glossary random block when main feature is enabled
+  In order to add the glossary random block to my course
+  As a teacher
+  It should be added to courses only if the glossary module is enabled.
+
+  Background:
+    Given the following "courses" exist:
+      | fullname | shortname | format |
+      | Course 1 | C1        | topics |
+    And I am on the "C1" "course" page logged in as "admin"
+
+  Scenario: The glossary random block can be added when glossary module is enabled
+    Given I turn editing mode on
+    When I click on "Add a block" "link"
+    Then I should see "Random glossary entry"
+
+  Scenario: The glossary random block cannot be added when glossary module is disabled
+    Given I navigate to "Plugins > Activity modules > Manage activities" in site administration
+    And I click on "Hide" "icon" in the "Glossary" "table_row"
+    And I am on "Course 1" course homepage with editing mode on
+    When I click on "Add a block" "link"
+    Then I should not see "Random glossary entry"

blocks/glossary_random/tests/behat/glossary_random_addblock_disabled.feature

@@ -0,0 +1,36 @@
+@block @block_glossary_random @javascript
+Feature: Add the glossary random block when main feature is disabled
+  In order to add the glossary random block to my course
+  As a teacher
+  It should be added to courses only if the glossary module is enabled.
+
+  Background:
+    Given the following "courses" exist:
+      | fullname | shortname | format |
+      | Course 1 | C1        | topics |
+    And I am on the "C1" "course" page logged in as "admin"
+
+  Scenario: The glossary random block is displayed even when glossary module is disabled
+    Given I turn editing mode on
+    And I add the "Random glossary entry" block
+    When I navigate to "Plugins > Activity modules > Manage activities" in site administration
+    And I click on "Hide" "icon" in the "Glossary" "table_row"
+    And I am on "Course 1" course homepage with editing mode on
+    Then I should see "Random glossary entry"
+
+  Scenario: The glossary random block can be removed even when glossary module is disabled
+    Given I turn editing mode on
+    And I add the "Random glossary entry" block
+    And I open the "Random glossary entry" blocks action menu
+    And I click on "Delete Random glossary entry block" "link" in the "Random glossary entry" "block"
+    And "Delete block?" "dialogue" should exist
+    And I click on "Cancel" "button" in the "Delete block?" "dialogue"
+    And I should see "Random glossary entry"
+    When I navigate to "Plugins > Activity modules > Manage activities" in site administration
+    And I click on "Hide" "icon" in the "Glossary" "table_row"
+    And I am on "Course 1" course homepage with editing mode on
+    And I open the "Random glossary entry" blocks action menu
+    And I click on "Delete Random glossary entry block" "link" in the "Random glossary entry" "block"
+    And "Delete block?" "dialogue" should exist
+    And I click on "Delete" "button" in the "Delete block?" "dialogue"
+    Then I should not see "Random glossary entry"

blocks/glossary_random/tests/glossary_random_test.php

@@ -0,0 +1,64 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace block_glossary_random\tests;
+
+use advanced_testcase;
+use block_glossary_random;
+use context_course;
+
+/**
+ * PHPUnit block_glossary_random tests
+ *
+ * @package    block_glossary_random
+ * @category   test
+ * @copyright  2021 Sara Arjona (sara@moodle.com)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @coversDefaultClass \block_glossary_random
+ */
+class glossary_random_test extends advanced_testcase {
+    public static function setUpBeforeClass(): void {
+        require_once(__DIR__ . '/../../moodleblock.class.php');
+        require_once(__DIR__ . '/../block_glossary_random.php');
+    }
+
+    /**
+     * Test the behaviour of can_block_be_added() method.
+     *
+     * @covers ::can_block_be_added
+     */
+    public function test_can_block_be_added(): void {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Create a course and prepare the page where the block will be added.
+        $course = $this->getDataGenerator()->create_course();
+        $page = new \moodle_page();
+        $page->set_context(context_course::instance($course->id));
+        $page->set_pagelayout('course');
+
+        $block = new block_glossary_random();
+        $pluginclass = \core_plugin_manager::resolve_plugininfo_class('mod');
+
+        // If glossary module is enabled, the method should return true.
+        $pluginclass::enable_plugin('glossary', 1);
+        $this->assertTrue($block->can_block_be_added($page));
+
+        // However, if the glossary module is disabled, the method should return false.
+        $pluginclass::enable_plugin('glossary', 0);
+        $this->assertFalse($block->can_block_be_added($page));
+    }
+}