diff --git a/.travis.yml b/.travis.yml
index 5a5c8fad6..9a6052d82 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -27,6 +27,10 @@ matrix:
     - name: "[PHP 7.2] PHP Unit tests"
       php: 7.2
       env: TEST_CONFIG="phpunit.xml.dist"
+    # 7.4
+    - name: "[PHP 7.4] PHP Unit tests"
+      php: 7.4
+      env: TEST_CONFIG="phpunit.xml.dist"
 
 # test only master (+ Pull requests)
 branches:
diff --git a/composer.json b/composer.json
index fd68675c5..86e7ddfdc 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
-    "name": "ezsystems/repository-forms",
     "description": "Use Symfony forms with eZ Platform repository objects",
+    "name": "ezsystems/repository-forms",
     "license": "GPL-2.0-only",
     "type": "ezplatform-bundle",
     "authors": [
@@ -16,8 +16,8 @@
         "jms/translation-bundle": "^1.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7|^6.0",
-        "matthiasnoback/symfony-dependency-injection-test": "~1.0|~2.0",
+        "phpunit/phpunit": "^7.5",
+        "matthiasnoback/symfony-dependency-injection-test": "~3.1",
         "behat/behat": "^3.0",
         "friendsofphp/php-cs-fixer": "^2.7"
     },
diff --git a/lib/FieldType/DataTransformer/SingleCountryValueTransformer.php b/lib/FieldType/DataTransformer/SingleCountryValueTransformer.php
index 1b1cbf646..9d35fd437 100644
--- a/lib/FieldType/DataTransformer/SingleCountryValueTransformer.php
+++ b/lib/FieldType/DataTransformer/SingleCountryValueTransformer.php
@@ -10,6 +10,7 @@
 
 use eZ\Publish\Core\FieldType\Country\Value;
 use Symfony\Component\Form\DataTransformerInterface;
+use Symfony\Component\Form\Exception\TransformationFailedException;
 
 /**
  * DataTransformer for Country\Value to be used with form type handling only single selection.
@@ -36,7 +37,16 @@ public function transform($value)
             return null;
         }
 
-        return current($value->countries)['Alpha2'];
+        if (empty($value->countries)) {
+            return null;
+        }
+
+        $country = current($value->countries);
+        if (!isset($country['Alpha2'])) {
+            throw new TransformationFailedException('Missing Alpha2 key');
+        }
+
+        return $country['Alpha2'];
     }
 
     public function reverseTransform($value)
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index fcde46be2..94fb5a4f6 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -5,8 +5,7 @@
          convertErrorsToExceptions="true"
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
-         beStrictAboutTestsThatDoNotTestAnything="false"
-         syntaxCheck="true">
+         beStrictAboutTestsThatDoNotTestAnything="false">
     <php>
         <ini name="error_reporting" value="-1" />
     </php>
diff --git a/tests/RepositoryForms/FieldType/DataTransformer/SingleCountryValueTransformerTest.php b/tests/RepositoryForms/FieldType/DataTransformer/SingleCountryValueTransformerTest.php
new file mode 100644
index 000000000..8e979ee52
--- /dev/null
+++ b/tests/RepositoryForms/FieldType/DataTransformer/SingleCountryValueTransformerTest.php
@@ -0,0 +1,103 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace EzSystems\RepositoryForms\Tests\FieldType\DataTransformer;
+
+use eZ\Publish\Core\FieldType\Country\Value;
+use EzSystems\RepositoryForms\FieldType\DataTransformer\SingleCountryValueTransformer;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
+final class SingleCountryValueTransformerTest extends TestCase
+{
+    private const COUNTRIES_INFO = [
+        'AF' => ['Name' => 'Afghanistan', 'Alpha2' => 'AF', 'Alpha3' => 'AFG', 'IDC' => '93'],
+        'AX' => ['Name' => 'Åland', 'Alpha2' => 'AX', 'Alpha3' => 'ALA', 'IDC' => '358'],
+        'AQ' => ['Name' => 'Antarctica', 'Alpha2' => 'AQ', 'Alpha3' => 'ATA', 'IDC' => '672'],
+        'AG' => ['Name' => 'Antigua and Barbuda', 'Alpha2' => 'AG', 'Alpha3' => 'ATG', 'IDC' => '1268'],
+        'AM' => ['Name' => 'Armenia', 'Alpha2' => 'AM', 'Alpha3' => 'ARM', 'IDC' => '374'],
+        'BB' => ['Name' => 'Barbados', 'Alpha2' => 'BB', 'Alpha3' => 'BRB', 'IDC' => '1246'],
+        'BJ' => ['Name' => 'Benin', 'Alpha2' => 'BJ', 'Alpha3' => 'BEN', 'IDC' => '229'],
+        'BM' => ['Name' => 'Bermuda', 'Alpha2' => 'BM', 'Alpha3' => 'BMU', 'IDC' => '1441'],
+        'BT' => ['Name' => 'Bhutan', 'Alpha2' => 'BT', 'Alpha3' => 'BTN', 'IDC' => '975'],
+        'BA' => ['Name' => 'Bosnia and Herzegovina', 'Alpha2' => 'BA', 'Alpha3' => 'BIH', 'IDC' => '387'],
+        'BW' => ['Name' => 'Botswana', 'Alpha2' => 'BW', 'Alpha3' => 'BWA', 'IDC' => '267'],
+        'BV' => ['Name' => 'Bouvet Island', 'Alpha2' => 'BV', 'Alpha3' => 'BVT', 'IDC' => '47'],
+        'IO' => ['Name' => 'British Indian Ocean Territory', 'Alpha2' => 'IO', 'Alpha3' => 'IOT', 'IDC' => '246'],
+        'BN' => ['Name' => 'Brunei Darussalam', 'Alpha2' => 'BN', 'Alpha3' => 'BRN', 'IDC' => '673'],
+        'BF' => ['Name' => 'Burkina Faso', 'Alpha2' => 'BF', 'Alpha3' => 'BFA', 'IDC' => '226'],
+        'KH' => ['Name' => 'Cambodia', 'Alpha2' => 'KH', 'Alpha3' => 'KHM', 'IDC' => '855'],
+        'CV' => ['Name' => 'Cape Verde', 'Alpha2' => 'CV', 'Alpha3' => 'CPV', 'IDC' => '238'],
+        'CF' => ['Name' => 'Central African Republic', 'Alpha2' => 'CF', 'Alpha3' => 'CAF', 'IDC' => '236'],
+        'CN' => ['Name' => 'China', 'Alpha2' => 'CN', 'Alpha3' => 'CHN', 'IDC' => '86'],
+        'CC' => ['Name' => 'Cocos (Keeling) Islands', 'Alpha2' => 'CC', 'Alpha3' => 'CCK', 'IDC' => '61'],
+        'BL' => ['Name' => 'Saint Barthélemy', 'Alpha2' => 'BL', 'Alpha3' => 'BLM', 'IDC' => '590'],
+        'GS' => ['Name' => 'South Georgia and The South Sandwich Islands', 'Alpha2' => 'GS', 'Alpha3' => 'SGS', 'IDC' => '500'],
+        'TW' => ['Name' => 'Taiwan', 'Alpha2' => 'TW', 'Alpha3' => 'TWN', 'IDC' => '886'],
+        'ZW' => ['Name' => 'Zimbabwe', 'Alpha2' => 'ZW', 'Alpha3' => 'ZWE', 'IDC' => '263'],
+    ];
+
+    /** @var \EzSystems\RepositoryForms\FieldType\DataTransformer\SingleCountryValueTransformer */
+    private $transformer;
+
+    protected function setUp(): void
+    {
+        $this->transformer = new SingleCountryValueTransformer(self::COUNTRIES_INFO);
+    }
+
+    /**
+     * @dataProvider dataProviderForTransform
+     */
+    public function testTransform(?Value $value, ?string $expectedValue): void
+    {
+        $this->assertEquals($expectedValue, $this->transformer->transform($value));
+    }
+
+    public function dataProviderForTransform(): iterable
+    {
+        yield 'country' => [
+            new Value(['ZW' => self::COUNTRIES_INFO['ZW']]),
+            'ZW',
+        ];
+
+        yield 'empty_array' => [
+            new Value([]),
+            null,
+        ];
+
+        yield 'null' => [null, null];
+    }
+
+    public function testTransformThrowsTransformationFailedException(): void
+    {
+        $this->expectException(TransformationFailedException::class);
+        $this->expectExceptionMessage('Missing Alpha2 key');
+
+        $this->transformer->transform(new Value([
+            'AF' => ['Name' => 'Afghanistan', 'Alpha3' => 'AFG', 'IDC' => '93'],
+        ]));
+    }
+
+    /**
+     * @dataProvider dataProviderForReverseTransform
+     */
+    public function testReverseTransform($value, ?Value $expectedValue): void
+    {
+        $this->assertEquals($expectedValue, $this->transformer->reverseTransform($value));
+    }
+
+    public function dataProviderForReverseTransform(): iterable
+    {
+        yield 'country' => [
+            'ZW',
+            new Value(['ZW' => self::COUNTRIES_INFO['ZW']]),
+        ];
+
+        yield 'null' => [null, null];
+    }
+}