diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c107478
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/vendor/
+/composer.lock
+/.phpunit.result.cache
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 7e81011..f246acc 100644
--- a/composer.json
+++ b/composer.json
@@ -16,12 +16,15 @@
         }
     ],
     "require": {
-        "php": ">=5.3.0"
+        "php": ">=7.2.0"
     },
     "suggest": {
         "symfony/css-selector": "Provides facilities is you prefers CSS to Xpath"
     },
     "autoload": {
         "psr-0": { "Welldom": "src/" }
+    },
+    "require-dev": {
+        "symfony/phpunit-bridge": "^5.0"
     }
 }
diff --git a/tests/Welldom/Tests/DocumentFragmentTest.php b/tests/Welldom/Tests/DocumentFragmentTest.php
index d14844d..c5548b7 100644
--- a/tests/Welldom/Tests/DocumentFragmentTest.php
+++ b/tests/Welldom/Tests/DocumentFragmentTest.php
@@ -11,25 +11,29 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
+
 /**
  * @covers \Welldom\DocumentFragment
  */
 class DocumentFragmentTest extends TestCase
 {
+    use TestHelpers;
+
     public function testAppendXmlError()
     {
         $doc = $this->createDocument('<foo />');
         $fragment = $doc->createDocumentFragment();
 
         $errors = $fragment->getLastErrors();
-        $this->assertInternalType('array', $errors);
+        $this->assertIsArray($errors);
         $this->assertCount(0, $errors);
 
         $success = $fragment->appendXML('<invalid att="v><test></invalid>');
         $this->assertSame(false, $success);
 
         $errors = $fragment->getLastErrors();
-        $this->assertInternalType('array', $errors);
+        $this->assertIsArray($errors);
         $this->assertCount(5, $errors);
     }
 
diff --git a/tests/Welldom/Tests/DocumentTest.php b/tests/Welldom/Tests/DocumentTest.php
index 46db65d..0341a67 100644
--- a/tests/Welldom/Tests/DocumentTest.php
+++ b/tests/Welldom/Tests/DocumentTest.php
@@ -11,6 +11,7 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
 use Welldom\Document;
 
 /**
@@ -18,6 +19,8 @@
  */
 class DocumentTest extends TestCase
 {
+    use TestHelpers;
+
     public function testConstructorEncoding()
     {
         $doc = Document::create('<foo />', 'UTF-8');
@@ -81,11 +84,11 @@ public function testLoadXMLError()
         $this->assertEquals(array(), $doc->getLastErrors());
 
         $this->assertFalse($doc->loadXML(''), '->loadXML() returns false with empty string');
-        $this->assertInternalType('array', $doc->getLastErrors());
+        $this->assertIsArray($doc->getLastErrors());
         $this->assertCount(1, $doc->getLastErrors());
 
         $this->assertFalse($doc->loadXML('<foo><bar></foo a="1>'), '->loadXML() returns false with invalid XML');
-        $this->assertInternalType('array', $doc->getLastErrors());
+        $this->assertIsArray($doc->getLastErrors());
         $this->assertCount(3, $doc->getLastErrors());
     }
 
diff --git a/tests/Welldom/Tests/ElementTest.php b/tests/Welldom/Tests/ElementTest.php
index a0575ff..cebe357 100644
--- a/tests/Welldom/Tests/ElementTest.php
+++ b/tests/Welldom/Tests/ElementTest.php
@@ -11,11 +11,15 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
+
 /**
  * @covers \Welldom\Element
  */
 class ElementTests extends TestCase
 {
+    use TestHelpers;
+
 // ->getDocument()
 
     public function testGetDocument()
diff --git a/tests/Welldom/Tests/NodeListTest.php b/tests/Welldom/Tests/NodeListTest.php
index bcdc5a2..03880f5 100644
--- a/tests/Welldom/Tests/NodeListTest.php
+++ b/tests/Welldom/Tests/NodeListTest.php
@@ -11,8 +11,11 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
+
 class NodeListTest extends TestCase
 {
+    use TestHelpers;
 
 // ->getIterator()
 
diff --git a/tests/Welldom/Tests/TestCase.php b/tests/Welldom/Tests/TestHelpers.php
similarity index 91%
rename from tests/Welldom/Tests/TestCase.php
rename to tests/Welldom/Tests/TestHelpers.php
index 033bc4e..9948534 100644
--- a/tests/Welldom/Tests/TestCase.php
+++ b/tests/Welldom/Tests/TestHelpers.php
@@ -13,7 +13,7 @@
 
 use Welldom\Document;
 
-class TestCase extends \PHPUnit_Framework_TestCase
+trait TestHelpers
 {
     /**
      * @param string $source XML source
diff --git a/tests/Welldom/Tests/XmlSerializerTest.php b/tests/Welldom/Tests/XmlSerializerTest.php
index 8dcffb3..e9031ed 100644
--- a/tests/Welldom/Tests/XmlSerializerTest.php
+++ b/tests/Welldom/Tests/XmlSerializerTest.php
@@ -11,6 +11,7 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
 use Welldom\XmlSerializer;
 
 /**
@@ -18,6 +19,8 @@
  */
 class XmlSerializerTest extends TestCase
 {
+    use TestHelpers;
+
     /**
      * @dataProvider dataForTestXmlToArrayToXml
      */
diff --git a/tests/Welldom/Tests/XpathTest.php b/tests/Welldom/Tests/XpathTest.php
index d67250b..b0e191a 100644
--- a/tests/Welldom/Tests/XpathTest.php
+++ b/tests/Welldom/Tests/XpathTest.php
@@ -11,6 +11,8 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
+use Welldom\Exception\InvalidXpathException;
 use Welldom\Xpath;
 
 /**
@@ -18,6 +20,7 @@
  */
 class XpathTest extends TestCase
 {
+    use TestHelpers;
 
     /**
      * @covers Welldom\Xpath::queryOne
@@ -32,10 +35,10 @@ public function testQueryOne()
 
     /**
      * @covers Welldom\Xpath::queryOne
-     * @expectedException \Welldom\Exception\InvalidXpathException
      */
     public function testQueryOneException()
     {
+        $this->expectException(InvalidXpathException::class);
         $this->getXpath('<foo/>')->queryOne('foo[');
     }
 
@@ -52,10 +55,10 @@ public function testQuery()
 
     /**
      * @covers Welldom\Xpath::query
-     * @expectedException \Welldom\Exception\InvalidXpathException
      */
     public function testQueryException()
     {
+        $this->expectException(InvalidXpathException::class);
         $this->getXpath('<foo/>')->query('foo[');
     }
 
@@ -71,10 +74,10 @@ public function testEvaluate()
 
     /**
      * @covers Welldom\Xpath::evaluate
-     * @expectedException \Welldom\Exception\InvalidXpathException
      */
     public function testEvaluateException()
     {
+        $this->expectException(InvalidXpathException::class);
         $this->getXpath('<foo/>')->evaluate('foo[');
     }
 
diff --git a/tests/Welldom/Tests/XsltProcessorCollectionTest.php b/tests/Welldom/Tests/XsltProcessorCollectionTest.php
index 249be06..18eb29c 100644
--- a/tests/Welldom/Tests/XsltProcessorCollectionTest.php
+++ b/tests/Welldom/Tests/XsltProcessorCollectionTest.php
@@ -11,6 +11,7 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
 use Welldom\XsltProcessorCollection;
 
 /**
@@ -18,6 +19,8 @@
  */
 class XsltProcessorCollectionTest extends TestCase
 {
+    use TestHelpers;
+
     public function testGetXsltProcessor()
     {
         $filename = FILES_DIR . '/frameworks.xsl';
@@ -27,19 +30,15 @@ public function testGetXsltProcessor()
         XsltProcessorCollection::free();
     }
 
-    /**
-     * @expectedException \DOMException
-     */
     public function testGetXsltProcessorLoadException()
     {
+        $this->expectException(\DOMException::class);
         XsltProcessorCollection::getXsltProcessor(FILES_DIR . '/frameworks-invalid.xsl');
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
     public function testGetXsltProcessorFileException()
     {
+        $this->expectException(\InvalidArgumentException::class);
         XsltProcessorCollection::getXsltProcessor(FILES_DIR . '/does-not-exists.xsl');
     }
 }
diff --git a/tests/Welldom/Tests/XsltProcessorTest.php b/tests/Welldom/Tests/XsltProcessorTest.php
index 180ae00..a865d42 100644
--- a/tests/Welldom/Tests/XsltProcessorTest.php
+++ b/tests/Welldom/Tests/XsltProcessorTest.php
@@ -11,6 +11,7 @@
 
 namespace Welldom\Tests;
 
+use PHPUnit\Framework\TestCase;
 use Welldom\XsltProcessor;
 use Welldom\Document;
 
@@ -19,6 +20,7 @@
  */
 class XsltProcessorTest extends TestCase
 {
+    use TestHelpers;
 
 // ->__construct()
 
@@ -29,7 +31,7 @@ public function testConstructor($filename, $errorsCount)
     {
         $xslt = new XsltProcessor(FILES_DIR . $filename);
 
-        $this->assertInternalType('array', $xslt->getLastErrors());
+        $this->assertIsArray($xslt->getLastErrors());
         $this->assertCount($errorsCount, $xslt->getLastErrors());
     }
 
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 02073ba..9ad57b1 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -10,5 +10,5 @@
  */
 
 require_once __DIR__ . '/../src/autoload.php';
-require_once __DIR__ . '/Welldom/Tests/TestCase.php';
+require_once __DIR__ . '/Welldom/Tests/TestHelpers.php';
 define('FILES_DIR', realpath(__DIR__ . '/_files'));