MDL-60738 webservice: Clean theme and lang properly

Sometimes the "theme" and "lang" fields in the user and course tables
in the database are set to incorrect values (uninstalled or
non-existent themes and language packs).
This makes Web Services functions to fail because the WS server
validate the returned data using the validate_param function that clean
parameters.

user/lib.php

@@ -564,6 +564,14 @@ function user_get_user_details($user, $course = null, array $userfields = array(
         }
     }
 
+    // Clean lang and auth fields for external functions (it may content uninstalled themes or language packs).
+    if (isset($userdetails['lang'])) {
+        $userdetails['lang'] = clean_param($userdetails['lang'], PARAM_LANG);
+    }
+    if (isset($userdetails['theme'])) {
+        $userdetails['theme'] = clean_param($userdetails['theme'], PARAM_THEME);
+    }
+
     return $userdetails;
 }
 

user/tests/externallib_test.php

@@ -222,8 +222,10 @@ class core_user_externallib_testcase extends externallib_advanced_testcase {
             'descriptionformat' => FORMAT_MOODLE,
             'city' => 'Perth',
             'url' => 'http://moodle.org',
-            'country' => 'AU'
-            );
+            'country' => 'AU',
+            'lang' => 'kkl',
+            'theme' => 'kkt',
+        );
         $user1 = self::getDataGenerator()->create_user($user1);
         if (!empty($CFG->usetags)) {
             require_once($CFG->dirroot . '/user/editlib.php');
@@ -328,6 +330,11 @@ class core_user_externallib_testcase extends externallib_advanced_testcase {
                 if (!empty($CFG->usetags) and !empty($generateduser->interests)) {
                     $this->assertEquals(implode(', ', $generateduser->interests), $returneduser['interests']);
                 }
+                // Check empty since incorrect values were used when creating the user.
+                if ($returneduser['id'] == $user1->id) {
+                    $this->assertEmpty($returneduser['lang']);
+                    $this->assertEmpty($returneduser['theme']);
+                }
             }
         }
 

user/tests/userlib_test.php

@@ -720,14 +720,16 @@ class core_userliblib_testcase extends advanced_testcase {
      * calling user_get_user_details() function.
      */
     public function test_user_get_user_details_missing_fields() {
+        global $CFG;
+
         $this->resetAfterTest(true);
         $this->setAdminUser(); // We need capabilities to view the data.
         $user = self::getDataGenerator()->create_user([
                                                           'auth'       => 'auth_something',
                                                           'confirmed'  => '0',
                                                           'idnumber'   => 'someidnumber',
-                                                          'lang'       => 'en_ar',
-                                                          'theme'      => 'mytheme',
+                                                          'lang'       => 'en',
+                                                          'theme'      => $CFG->theme,
                                                           'timezone'   => '50',
                                                           'mailformat' => '0',
                                                       ]);
@@ -737,8 +739,8 @@ class core_userliblib_testcase extends advanced_testcase {
         self::assertSame('auth_something', $got['auth']);
         self::assertSame('0', $got['confirmed']);
         self::assertSame('someidnumber', $got['idnumber']);
-        self::assertSame('en_ar', $got['lang']);
-        self::assertSame('mytheme', $got['theme']);
+        self::assertSame('en', $got['lang']);
+        self::assertSame($CFG->theme, $got['theme']);
         self::assertSame('50', $got['timezone']);
         self::assertSame('0', $got['mailformat']);
     }