Реализован обработчик для смены языка аккаунта

tests/codeception/api/_pages/AccountsRoute.php

@@ -50,4 +50,11 @@ class AccountsRoute extends BasePage {
         ]);
     }
 
+    public function changeLang($lang = null) {
+        $this->route = ['accounts/change-lang'];
+        $this->actor->sendPOST($this->getUrl(), [
+            'lang' => $lang,
+        ]);
+    }
+
 }

tests/codeception/api/functional/AccountsChangeLangCest.php

@@ -0,0 +1,31 @@
+<?php
+namespace tests\codeception\api\functional;
+
+use Codeception\Specify;
+use tests\codeception\api\_pages\AccountsRoute;
+use tests\codeception\api\FunctionalTester;
+
+class AccountsChangeLangCest {
+
+    /**
+     * @var AccountsRoute
+     */
+    private $route;
+
+    public function _before(FunctionalTester $I) {
+        $this->route = new AccountsRoute($I);
+    }
+
+    public function testSubmitNewEmail(FunctionalTester $I) {
+        $I->wantTo('change my account language');
+        $I->loggedInAsActiveAccount();
+
+        $this->route->changeLang('ru');
+        $I->canSeeResponseCodeIs(200);
+        $I->canSeeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'success' => true,
+        ]);
+    }
+
+}

tests/codeception/api/unit/models/profile/ChangeLanguageFormTest.php

@@ -0,0 +1,36 @@
+<?php
+namespace codeception\api\unit\models\profile;
+
+use api\models\profile\ChangeLanguageForm;
+use Codeception\Specify;
+use common\models\Account;
+use tests\codeception\api\unit\DbTestCase;
+use tests\codeception\common\fixtures\AccountFixture;
+
+/**
+ * @property AccountFixture $accounts
+ */
+class ChangeLanguageFormTest extends DbTestCase {
+    use Specify;
+
+    public function fixtures() {
+        return [
+            'accounts' => [
+                'class' => AccountFixture::class,
+                'dataFile' => '@tests/codeception/common/fixtures/data/accounts.php',
+            ],
+        ];
+    }
+
+    public function testApplyLanguage() {
+        $this->specify('language changed', function() {
+            /** @var Account $account */
+            $account = Account::findOne($this->accounts['admin']);
+            $model = new ChangeLanguageForm($account);
+            $model->lang = 'ru';
+            expect($model->applyLanguage())->true();
+            expect($account->lang)->equals('ru');
+        });
+    }
+
+}