diff --git a/.gitignore b/.gitignore
index 9253b5f6..809dc4fc 100755
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@
 /.idea
 composer.lock
 vendor/
+/.phpunit.result.cache
 
diff --git a/.travis.yml b/.travis.yml
index 4380fb4a..1b16d8e0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,8 @@ cache:
 php:
   - 7.1
   - 7.2
+  - 7.3
+  - 7.4
 
 matrix:
   include:
@@ -16,9 +18,7 @@ matrix:
 
 before_script:
   - pecl install xmldiff
-  - echo "xdebug.max_nesting_level=1000" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
-  - if [[ $TRAVIS_PHP_VERSION == '7.'* ]]; then composer --dev require ocramius/package-versions:^1.0 --no-update; fi
-
+  - if [[ $TRAVIS_PHP_VERSION == '7.1' && $COMPOSER_FLAGS == '--prefer-lowest --prefer-stable' ]]; then composer --dev require ocramius/package-versions:^1.0 --no-update; fi
   - composer update $COMPOSER_FLAGS
 
 script:
diff --git a/composer.json b/composer.json
index 89d7ded5..24528b49 100644
--- a/composer.json
+++ b/composer.json
@@ -30,7 +30,7 @@
     "psr/log": "^1.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^4.8|^5.0",
+    "phpunit/phpunit": "^7.0|^8.0",
     "jms/serializer": "^1.9|^2.0|^3.0",
     "goetas-webservices/xsd2php-runtime": "^0.2.8@dev",
     "symfony/validator": "^2.3.24|^3.0|^4.0",
diff --git a/tests/Converter/AbstractXsdConverterTest.php b/tests/Converter/AbstractXsdConverterTest.php
index ebddea14..55a83825 100644
--- a/tests/Converter/AbstractXsdConverterTest.php
+++ b/tests/Converter/AbstractXsdConverterTest.php
@@ -1,9 +1,13 @@
 <?php
 namespace GoetasWebservices\Xsd\XsdToPhp\Tests\Converter;
 
+use GoetasWebservices\Xsd\XsdToPhp\AbstractConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
+use GoetasWebservices\Xsd\XsdToPhp\Tests\ReflectionUtils;
+use PHPUnit\Framework\Assert;
+use PHPUnit\Framework\TestCase;
 
-class AbstractXsdConverterTest extends \PHPUnit_Framework_TestCase
+class AbstractXsdConverterTest extends TestCase
 {
 
     /**
@@ -12,7 +16,7 @@ class AbstractXsdConverterTest extends \PHPUnit_Framework_TestCase
      */
     protected $converter;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->converter = $this->getMockForAbstractClass('GoetasWebservices\Xsd\XsdToPhp\AbstractConverter', [new ShortNamingStrategy()]);
     }
@@ -23,7 +27,7 @@ public function testAliases()
         };
         $this->converter->addAliasMap('http://www.example.com', "myType", $f);
 
-        $handlers = \PHPUnit_Framework_Assert::readAttribute($this->converter, 'typeAliases');
+        $handlers = ReflectionUtils::getObjectAttribute($this->converter, 'typeAliases');
 
         $this->assertArrayHasKey('http://www.example.com', $handlers);
         $this->assertArrayHasKey('myType', $exmpleHandlers = $handlers['http://www.example.com']);
@@ -32,7 +36,7 @@ public function testAliases()
 
     public function testDefaultAliases()
     {
-        $handlers = \PHPUnit_Framework_Assert::readAttribute($this->converter, 'typeAliases');
+        $handlers = ReflectionUtils::getObjectAttribute($this->converter, 'typeAliases');
 
         $this->assertArrayHasKey('http://www.w3.org/2001/XMLSchema', $handlers);
         $defaultHandlers = $handlers['http://www.w3.org/2001/XMLSchema'];
@@ -46,7 +50,7 @@ public function testNamespaces()
     {
         $this->converter->addNamespace('http://www.example.com', 'some\php\ns');
 
-        $namespaces = \PHPUnit_Framework_Assert::readAttribute($this->converter, 'namespaces');
+        $namespaces = ReflectionUtils::getObjectAttribute($this->converter, 'namespaces');
 
         $this->assertArrayHasKey('http://www.example.com', $namespaces);
         $this->assertEquals('some\php\ns', $namespaces['http://www.example.com']);
diff --git a/tests/Converter/JMS/Xsd2JmsBase.php b/tests/Converter/JMS/Xsd2JmsBase.php
index 3000b12f..9b88483a 100644
--- a/tests/Converter/JMS/Xsd2JmsBase.php
+++ b/tests/Converter/JMS/Xsd2JmsBase.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Jms\YamlConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-abstract class Xsd2JmsBase extends \PHPUnit_Framework_TestCase
+abstract class Xsd2JmsBase extends TestCase
 {
     /**
      *
@@ -19,7 +20,7 @@ abstract class Xsd2JmsBase extends \PHPUnit_Framework_TestCase
      */
     protected $reader;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->converter = new YamlConverter(new ShortNamingStrategy());
         $this->converter->addNamespace('http://www.example.com', "Example");
diff --git a/tests/Converter/PHP/Xsd2PhpBase.php b/tests/Converter/PHP/Xsd2PhpBase.php
index 6b2b09f5..ac0c2385 100644
--- a/tests/Converter/PHP/Xsd2PhpBase.php
+++ b/tests/Converter/PHP/Xsd2PhpBase.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-abstract class Xsd2PhpBase extends \PHPUnit_Framework_TestCase
+abstract class Xsd2PhpBase extends TestCase
 {
     /**
      *
@@ -19,7 +20,7 @@ abstract class Xsd2PhpBase extends \PHPUnit_Framework_TestCase
      */
     protected $reader;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->converter = new PhpConverter(new ShortNamingStrategy());
         $this->converter->addNamespace('http://www.example.com', "Example");
diff --git a/tests/Converter/Validator/Xsd2ValidatorTest.php b/tests/Converter/Validator/Xsd2ValidatorTest.php
index ba0bda17..9557b5ff 100644
--- a/tests/Converter/Validator/Xsd2ValidatorTest.php
+++ b/tests/Converter/Validator/Xsd2ValidatorTest.php
@@ -5,8 +5,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Jms\YamlValidatorConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class Xsd2ValidatorTest extends \PHPUnit_Framework_TestCase
+class Xsd2ValidatorTest extends TestCase
 {
     /**
      * @var YamlValidatorConverter
@@ -21,7 +22,7 @@ class Xsd2ValidatorTest extends \PHPUnit_Framework_TestCase
     /**
      * Set up converter and reader properties
      */
-    public function setUp()
+    public function setUp(): void
     {
         $this->converter = new YamlValidatorConverter(new ShortNamingStrategy());
         $this->converter->addNamespace('http://www.example.com', "Example");
diff --git a/tests/Issues/I111/I111Test.php b/tests/Issues/I111/I111Test.php
index 513eb630..b3194eef 100644
--- a/tests/Issues/I111/I111Test.php
+++ b/tests/Issues/I111/I111Test.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\XML\XSDReader\SchemaReader;
 use GoetasWebservices\Xsd\XsdToPhp\Jms\YamlConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
+use PHPUnit\Framework\TestCase;
 
-class I111Test extends \PHPUnit_Framework_TestCase{
+class I111Test extends TestCase {
 
     public function testNamespace()
     {
diff --git a/tests/Issues/I22/I22Test.php b/tests/Issues/I22/I22Test.php
index 3a62016b..b430a19f 100644
--- a/tests/Issues/I22/I22Test.php
+++ b/tests/Issues/I22/I22Test.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\XML\XSDReader\SchemaReader;
 use GoetasWebservices\Xsd\XsdToPhp\Jms\YamlConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
+use PHPUnit\Framework\TestCase;
 
-class I22Test extends \PHPUnit_Framework_TestCase{
+class I22Test extends TestCase {
 
     public function testNamespace()
     {
diff --git a/tests/Issues/I26/I26Test.php b/tests/Issues/I26/I26Test.php
index 508c73e9..f5955575 100644
--- a/tests/Issues/I26/I26Test.php
+++ b/tests/Issues/I26/I26Test.php
@@ -5,8 +5,9 @@
 use GoetasWebservices\XML\XSDReader\SchemaReader;
 use GoetasWebservices\Xsd\XsdToPhp\Jms\YamlConverter;
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
+use PHPUnit\Framework\TestCase;
 
-class I26Test extends \PHPUnit_Framework_TestCase
+class I26Test extends TestCase
 {
     public function testSkipWhenEmptyOnOptionalAndRequiredLists()
     {
diff --git a/tests/Issues/I40/I40Test.php b/tests/Issues/I40/I40Test.php
index 9ac8cd2d..52e45009 100644
--- a/tests/Issues/I40/I40Test.php
+++ b/tests/Issues/I40/I40Test.php
@@ -7,8 +7,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Php\Structure\PHPClass;
 use GoetasWebservices\Xsd\XsdToPhp\Php\Structure\PHPProperty;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class I40Test extends \PHPUnit_Framework_TestCase
+class I40Test extends TestCase
 {
 
     public function testMissingClass()
diff --git a/tests/Issues/I43/.gitignore b/tests/Issues/I43/.gitignore
new file mode 100644
index 00000000..c0363794
--- /dev/null
+++ b/tests/Issues/I43/.gitignore
@@ -0,0 +1 @@
+tmp/
\ No newline at end of file
diff --git a/tests/Issues/I43/I43Test.php b/tests/Issues/I43/I43Test.php
index e0c69c7c..69a68d1c 100644
--- a/tests/Issues/I43/I43Test.php
+++ b/tests/Issues/I43/I43Test.php
@@ -6,8 +6,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
 use GoetasWebservices\Xsd\XsdToPhp\Tests\Generator;
+use PHPUnit\Framework\TestCase;
 
-class I43Test extends \PHPUnit_Framework_TestCase
+class I43Test extends TestCase
 {
     /**
      * @group long
diff --git a/tests/Issues/I57/I57Test.php b/tests/Issues/I57/I57Test.php
index 4a5f77de..fc117961 100644
--- a/tests/Issues/I57/I57Test.php
+++ b/tests/Issues/I57/I57Test.php
@@ -5,8 +5,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class I57Test extends \PHPUnit_Framework_TestCase
+class I57Test extends TestCase
 {
 
     public function testMissingClass()
diff --git a/tests/Issues/I63/I63Test.php b/tests/Issues/I63/I63Test.php
index 0a595bb0..25e39419 100644
--- a/tests/Issues/I63/I63Test.php
+++ b/tests/Issues/I63/I63Test.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class I63Test extends \PHPUnit_Framework_TestCase
+class I63Test extends TestCase
 {
 
     public function testNaming()
diff --git a/tests/Issues/I84/I84Test.php b/tests/Issues/I84/I84Test.php
index b7f2259d..400e4650 100644
--- a/tests/Issues/I84/I84Test.php
+++ b/tests/Issues/I84/I84Test.php
@@ -4,8 +4,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Naming\ShortNamingStrategy;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class I84Test extends \PHPUnit_Framework_TestCase
+class I84Test extends TestCase
 {
 
     public function testNaming()
diff --git a/tests/JmsSerializer/OTA/OTASerializationTest.php b/tests/JmsSerializer/OTA/OTASerializationTest.php
index 0c0b14a6..c92181f7 100644
--- a/tests/JmsSerializer/OTA/OTASerializationTest.php
+++ b/tests/JmsSerializer/OTA/OTASerializationTest.php
@@ -10,9 +10,10 @@
 use GoetasWebservices\Xsd\XsdToPhpRuntime\Jms\Handler\XmlSchemaDateHandler;
 use JMS\Serializer\Handler\HandlerRegistryInterface;
 use PackageVersions\Versions;
+use PHPUnit\Framework\TestCase;
 use Symfony\Component\Validator\Validator\ValidatorInterface;
 
-class OTASerializationTest extends \PHPUnit_Framework_TestCase
+class OTASerializationTest extends TestCase
 {
     /**
      * @var Generator
@@ -27,7 +28,7 @@ class OTASerializationTest extends \PHPUnit_Framework_TestCase
     private static $namespace = 'OTA';
     private static $files = [];
 
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         if (!self::$files) {
             self::$files = self::getXmlFiles();
@@ -53,7 +54,7 @@ public static function setUpBeforeClass()
         self::$validator = self::$generator->getValidator($schemas);
     }
 
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
         self::$generator->unRegisterAutoloader();
         self::$generator->cleanDirectories();
@@ -203,6 +204,8 @@ public function testValidation($xml, $xsd, $class)
 
         if (@$xmlDom->schemaValidate($xsd)) {
             $this->assertCount(0, $violations, 'Validation errors in '.$xml);
+        } else {
+            $this->assertTrue(true);
         }
     }
 
diff --git a/tests/PHP/AnyTypePHPConversionTest.php b/tests/PHP/AnyTypePHPConversionTest.php
index 34808e8d..d839a3f2 100644
--- a/tests/PHP/AnyTypePHPConversionTest.php
+++ b/tests/PHP/AnyTypePHPConversionTest.php
@@ -6,8 +6,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Php\ClassGenerator;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class AnyTypePHPConversionTest extends \PHPUnit_Framework_TestCase
+class AnyTypePHPConversionTest extends TestCase
 {
 
     /**
diff --git a/tests/PHP/PHPConversionTest.php b/tests/PHP/PHPConversionTest.php
index d16df851..a52e820e 100644
--- a/tests/PHP/PHPConversionTest.php
+++ b/tests/PHP/PHPConversionTest.php
@@ -5,8 +5,9 @@
 use GoetasWebservices\Xsd\XsdToPhp\Php\ClassGenerator;
 use GoetasWebservices\Xsd\XsdToPhp\Php\PhpConverter;
 use GoetasWebservices\XML\XSDReader\SchemaReader;
+use PHPUnit\Framework\TestCase;
 
-class PHPConversionTest extends \PHPUnit_Framework_TestCase
+class PHPConversionTest extends TestCase
 {
 
     /**
diff --git a/tests/PathGenerator/JMSPathGeneratorTest.php b/tests/PathGenerator/JMSPathGeneratorTest.php
index 1b288fab..3438874f 100644
--- a/tests/PathGenerator/JMSPathGeneratorTest.php
+++ b/tests/PathGenerator/JMSPathGeneratorTest.php
@@ -2,12 +2,13 @@
 namespace GoetasWebservices\Xsd\XsdToPhp\Tests\Php\PathGenerator;
 
 use GoetasWebservices\Xsd\XsdToPhp\Jms\PathGenerator\Psr4PathGenerator;
+use PHPUnit\Framework\TestCase;
 
-class JMSPathGeneratorTest extends \PHPUnit_Framework_TestCase
+class JMSPathGeneratorTest extends TestCase
 {
     protected $tmpdir;
 
-    public function setUp()
+    public function setUp(): void
     {
         $tmp = sys_get_temp_dir();
 
@@ -23,7 +24,7 @@ public function setUp()
 
     public function testNoNs()
     {
-        $this->setExpectedException('GoetasWebservices\Xsd\XsdToPhp\PathGenerator\PathGeneratorException');
+        $this->expectException('GoetasWebservices\Xsd\XsdToPhp\PathGenerator\PathGeneratorException');
         $generator = new Psr4PathGenerator(array(
             'myns2\\' => $this->tmpdir
         ));
diff --git a/tests/PathGenerator/PHPPathGeneratorTest.php b/tests/PathGenerator/PHPPathGeneratorTest.php
index 55daa333..24593ed3 100644
--- a/tests/PathGenerator/PHPPathGeneratorTest.php
+++ b/tests/PathGenerator/PHPPathGeneratorTest.php
@@ -4,12 +4,13 @@
 use GoetasWebservices\Xsd\XsdToPhp\Php\PathGenerator\Psr4PathGenerator;
 use GoetasWebservices\Xsd\XsdToPhp\Php\Structure\PHPClass;
 use Laminas\Code\Generator\ClassGenerator;
+use PHPUnit\Framework\TestCase;
 
-class PHPPathGeneratorTest extends \PHPUnit_Framework_TestCase
+class PHPPathGeneratorTest extends TestCase
 {
     protected $tmpdir;
 
-    public function setUp()
+    public function setUp(): void
     {
         $tmp = sys_get_temp_dir();
 
@@ -25,7 +26,7 @@ public function setUp()
 
     public function testNoNs()
     {
-        $this->setExpectedException('GoetasWebservices\Xsd\XsdToPhp\PathGenerator\PathGeneratorException');
+        $this->expectException('GoetasWebservices\Xsd\XsdToPhp\PathGenerator\PathGeneratorException');
         $generator = new Psr4PathGenerator(array(
             'myns\\' => $this->tmpdir
         ));
diff --git a/tests/ReflectionUtils.php b/tests/ReflectionUtils.php
new file mode 100644
index 00000000..13503fda
--- /dev/null
+++ b/tests/ReflectionUtils.php
@@ -0,0 +1,55 @@
+<?php
+
+
+namespace GoetasWebservices\Xsd\XsdToPhp\Tests;
+
+
+use PHPUnit\Framework\Exception;
+use PHPUnit\Framework\InvalidArgumentException;
+use ReflectionObject;
+
+class ReflectionUtils
+{
+    /**
+     * Returns the value of an object's attribute.
+     * This also works for attributes that are declared protected or private.
+     *
+     * @param object $object
+     *
+     * @throws Exception
+     *
+     * @codeCoverageIgnore
+     */
+    public static function getObjectAttribute($object, string $attributeName)
+    {
+        if (!\is_object($object)) {
+            throw InvalidArgumentException::create(1, 'object');
+        }
+
+        $reflector = new ReflectionObject($object);
+
+        do {
+            try {
+                $attribute = $reflector->getProperty($attributeName);
+
+                if (!$attribute || $attribute->isPublic()) {
+                    return $object->$attributeName;
+                }
+
+                $attribute->setAccessible(true);
+                $value = $attribute->getValue($object);
+                $attribute->setAccessible(false);
+
+                return $value;
+            } catch (\ReflectionException $e) {
+            }
+        } while ($reflector = $reflector->getParentClass());
+
+        throw new Exception(
+            \sprintf(
+                'Attribute "%s" not found in object.',
+                $attributeName
+            )
+        );
+    }
+}
\ No newline at end of file
diff --git a/tests/Validator/ValidatorTest.php b/tests/Validator/ValidatorTest.php
index 8e5f0784..b68b4432 100644
--- a/tests/Validator/ValidatorTest.php
+++ b/tests/Validator/ValidatorTest.php
@@ -2,19 +2,20 @@
 namespace GoetasWebservices\Xsd\XsdToPhp\Tests\Php\PathGenerator;
 
 use Composer\Autoload\ClassLoader;
+use PHPUnit\Framework\TestCase;
 use Symfony\Component\Validator\Validation;
 use Symfony\Component\Validator\Validator\ValidatorInterface;
 
 use ota\TestNotNullType;
 
-class ValidatorTest extends \PHPUnit_Framework_TestCase
+class ValidatorTest extends TestCase
 {
     /**
      * @var ValidatorInterface
      */
     protected $validator;
 
-    public function setUp()
+    public function setUp(): void
     {
         $loader = new ClassLoader();
         $loader->addPsr4("ota\\", __DIR__."/ota/php");