Add AppStrings Legacy Handler

- Add AppStrings Legacy handler
-- Inject some User module key into app strings
- Update AppStrings Item data provider to use legacy handler
- Add unit tests for legacy handler

tests/unit/legacy/AppStringsHandlerTest.php

@@ -0,0 +1,68 @@
+<?php namespace App\Tests;
+
+use ApiPlatform\Core\Exception\ItemNotFoundException;
+use App\Entity\AppStrings;
+use Codeception\Test\Unit;
+use SuiteCRM\Core\Legacy\AppStringsHandler;
+
+class AppStringsHandlerTest extends Unit
+{
+    /**
+     * @var UnitTester
+     */
+    protected $tester;
+
+    /**
+     * @var AppStringsHandler
+     */
+    protected $handler;
+
+    protected function _before()
+    {
+        $projectDir = codecept_root_dir();
+        $legacyDir = $projectDir . '/legacy';
+        $legacySessionName = 'LEGACYSESSID';
+        $defaultSessionName = 'PHPSESSID';
+        $this->handler = new AppStringsHandler($projectDir, $legacyDir, $legacySessionName, $defaultSessionName);
+    }
+
+    protected function _after()
+    {
+    }
+
+    // tests
+    public function testInvalidLanguageCheck()
+    {
+        $this->expectException(ItemNotFoundException::class);
+        $this->handler->getAppStrings('invalid_lang');
+    }
+
+    public function testDefaultLanguageKey()
+    {
+        $appStrings = $this->handler->getAppStrings('en_us');
+        static::assertNotNull($appStrings);
+        static::assertEquals('en_us', $appStrings->getId());
+        static::assertIsArray($appStrings->getItems());
+        $this->assertLanguageKey('LBL_LOGOUT', $appStrings);
+        $this->assertLanguageKey('LBL_LOGIN_BUTTON_LABEL', $appStrings);
+        $this->assertLanguageKey('LBL_LOGIN_BUTTON_TITLE', $appStrings);
+        $this->assertLanguageKey('LBL_LOGIN_FORGOT_PASSWORD', $appStrings);
+        $this->assertLanguageKey('LBL_LOGIN_SUBMIT', $appStrings);
+        $this->assertLanguageKey('LBL_USER_NAME', $appStrings);
+        $this->assertLanguageKey('LBL_USER_NAME', $appStrings);
+        $this->assertLanguageKey('ERR_INVALID_PASSWORD', $appStrings);
+        $this->assertLanguageKey('LBL_PASSWORD', $appStrings);
+    }
+
+    /**
+     * Asserts that the given label $key exists in appStrings
+     * @param string $key
+     * @param AppStrings $appStrings
+     */
+    protected function assertLanguageKey($key, AppStrings $appStrings)
+    {
+        static::assertArrayHasKey($key, $appStrings->getItems());
+        static::assertNotEmpty($appStrings->getItems()[$key]);
+    }
+
+}