MDL-83504 user: reset preference cache in unittests

lib/classes/user.php

@@ -886,6 +886,7 @@ class user {
      */
     public static function reset_caches() {
         self::$propertiescache = null;
+        self::$preferencescache = null;
     }
 
     /**

user/tests/editlib_test.php

@@ -109,4 +109,56 @@ class editlib_test extends \advanced_testcase {
         // Tidy up after we finish testing.
         $CFG->fullnamedisplay = $originalcfg->fullnamedisplay;
     }
+
+    /**
+     * Provider for test_useredit_update_user_preference
+     *
+     * @return array
+     */
+    public static function useredit_update_user_preference_provider(): array {
+        return [
+            'Homepage fixed' => [HOMEPAGE_SITE, [], HOMEPAGE_MYCOURSES, null],
+            'Simple user pref' => [HOMEPAGE_USER, [], HOMEPAGE_MYCOURSES, (string)HOMEPAGE_MYCOURSES],
+            'Extra option' => [HOMEPAGE_USER, ['/helloworld'], '/helloworld', '/helloworld'],
+            'Invalid option' => [HOMEPAGE_USER, [], '/helloworld', (string)HOMEPAGE_MY],
+        ];
+    }
+
+    /**
+     * Tests for function useredit_update_user_preference
+     *
+     * @dataProvider useredit_update_user_preference_provider
+     * @covers ::useredit_update_user_preference
+     * @param int $defaulthomepage to be set as the default homepage
+     * @param array $extraoptions additional options for the pref value that are added in the hook callbacks
+     * @param int|string $setting what we are trying to set as a user preference
+     * @param string|null $expected what will be actually set in the user preference
+     */
+    public function test_useredit_update_user_preference(int $defaulthomepage, array $extraoptions,
+            $setting, ?string $expected): void {
+        global $DB, $CFG, $USER;
+        $this->resetAfterTest();
+        $user = $this->getDataGenerator()->create_user();
+        $this->setUser($user);
+
+        if ($extraoptions) {
+            // Pretend we have hook callbacks adding extra allowed options.
+            $testcallback = function(\core_user\hook\extend_default_homepage $hook) use ($extraoptions) {
+                foreach ($extraoptions as $localurl) {
+                    $hook->add_option(new \moodle_url($localurl), new \lang_string('yes'));
+                }
+            };
+            $this->redirectHook(\core_user\hook\extend_default_homepage::class, $testcallback);
+        }
+
+        set_config('defaulthomepage', $defaulthomepage);
+        useredit_update_user_preference([
+            'id' => $user->id,
+            'preference_user_home_page_preference' => $setting,
+        ]);
+
+        // Ensure user preference returns expected value.
+        $preference = get_user_preferences('user_home_page_preference', null, $user);
+        $this->assertSame($expected, $preference);
+    }
 }