diff --git a/.gitignore b/.gitignore
index 6531974..3fd5f04 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,4 +10,3 @@ coveralls-upload.json
 vendor
 composer.lock
 bin
-
diff --git a/.travis.yml b/.travis.yml
index 13a0d20..fdbb482 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,11 +1,9 @@
 language: php
 
 php:
-    - 5.4
-    - 5.5
-    - 5.6
-    - 7.0
-    - hhvm
+    - 7.3
+    - 7.4
+    - 8.0
 
 sudo: false
 
diff --git a/README.md b/README.md
index 7a0e577..c4662f8 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Totem
        \\\\////
         |.)(.|
         | || |   Changeset calculator between two state of a data
-        \(__)/   Requires PHP 5.4 ; Compatible PHP 5.5, PHP 5.6, PHP 7 and HHVM
+        \(__)/   Compatibile with PHP 7.3, 7.4 or 8.0
         |-..-|
         |o\/o|
    .----\    /----.
diff --git a/composer.json b/composer.json
index 36e1802..a72facf 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
     },
 
     "require": {
-        "php": "^5.4 || ^7.0",
+        "php": "^7.3 || ^8.0",
         "symfony/property-access": "^2.5 || ^3.0"
     },
 
@@ -40,5 +40,9 @@
         "branch-alias": {
             "dev-master": "1.5.0-dev"
         }
+    },
+
+    "require-dev": {
+        "phpunit/phpunit": "^9.5"
     }
 }
diff --git a/phpunit.xml b/phpunit.xml
index 725a7e7..da9d5a5 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,28 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
-
 <!-- http://www.phpunit.de/manual/current/en/appendixes.configuration.html -->
-<phpunit
-    backupGlobals               = "false"
-    backupStaticAttributes      = "false"
-    colors                      = "true"
-    convertErrorsToExceptions   = "true"
-    convertNoticesToExceptions  = "true"
-    convertWarningsToExceptions = "true"
-    processIsolation            = "false"
-    stopOnFailure               = "false"
-    syntaxCheck                 = "false"
-    bootstrap                   = "./vendor/autoload.php">
-
-    <testsuites>
-        <testsuite name="Project Test Suite">
-            <directory>./test</directory>
-        </testsuite>
-    </testsuites>
-
-    <filter>
-        <whitelist>
-            <directory suffix=".php">./src</directory>
-        </whitelist>
-    </filter>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" backupGlobals="false" backupStaticAttributes="false" colors="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" processIsolation="false" stopOnFailure="false" bootstrap="./vendor/autoload.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage>
+    <include>
+      <directory suffix=".php">./src</directory>
+    </include>
+  </coverage>
+  <testsuites>
+    <testsuite name="Project Test Suite">
+      <directory>./test</directory>
+    </testsuite>
+  </testsuites>
 </phpunit>
-
diff --git a/src/AbstractSnapshot.php b/src/AbstractSnapshot.php
index 7c677e9..72758c4 100644
--- a/src/AbstractSnapshot.php
+++ b/src/AbstractSnapshot.php
@@ -104,15 +104,6 @@ final public function getDataKeys()
         return array_keys($this->getComparableData());
     }
 
-    /**
-     * Clone this object
-     *
-     * @codeCoverageIgnore
-     */
-    final private function __clone()
-    {
-    }
-
     /** {@inheritDoc} */
     final public function offsetExists($offset)
     {
diff --git a/src/Set.php b/src/Set.php
index 4ea6296..e05117a 100644
--- a/src/Set.php
+++ b/src/Set.php
@@ -25,8 +25,6 @@
 use Totem\Change\Addition;
 use Totem\Change\Modification;
 
-use Totem\SetInterface;
-use Totem\AbstractSnapshot;
 use Totem\Snapshot\CollectionSnapshot;
 
 /**
diff --git a/src/SetInterface.php b/src/SetInterface.php
index 19c21fe..a0e1f4c 100644
--- a/src/SetInterface.php
+++ b/src/SetInterface.php
@@ -11,8 +11,6 @@
 
 namespace Totem;
 
-use Totem\AbstractSnapshot;
-
 /**
  * Represents a set of changes between two data
  *
diff --git a/test/AbstractChangeTest.php b/test/AbstractChangeTest.php
index 9d35e8d..8864e7f 100644
--- a/test/AbstractChangeTest.php
+++ b/test/AbstractChangeTest.php
@@ -11,14 +11,14 @@
 
 namespace Totem;
 
-use PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase;
 
-class AbstractChangeTest extends PHPUnit_Framework_TestCase
+class AbstractChangeTest extends TestCase
 {
     /** @var Totem\AbstractChange */
     private $mock;
 
-    public function setUp()
+    protected function setUp(): void
     {
         $this->mock = $this->getMockForAbstractClass('Totem\\AbstractChange', ['old', 'new']);
     }
diff --git a/test/AbstractSnapshotTest.php b/test/AbstractSnapshotTest.php
index 7253425..446f01d 100644
--- a/test/AbstractSnapshotTest.php
+++ b/test/AbstractSnapshotTest.php
@@ -11,29 +11,29 @@
 
 namespace Totem;
 
+use BadMethodCallException;
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
 use ReflectionMethod;
 use ReflectionProperty;
+use Totem\Exception\IncomparableDataException;
 
-use PHPUnit_Framework_TestCase;
-
-class AbstractSnapshotTest extends PHPUnit_Framework_TestCase
+class AbstractSnapshotTest extends TestCase
 {
-    /**
-     * @expectedException        Totem\Exception\IncomparableDataException
-     * @expectedExceptionMessage This data is not comparable with the base
-     */
     public function testDiffIncomparable()
     {
+        $this->expectException(IncomparableDataException::class);
+        $this->expectExceptionMessage('This data is not comparable with the base');
+
         $snapshot = new Snapshot(['comparable' => false]);
         $snapshot->diff($snapshot);
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The computed data is not an array, "string" given
-     */
     public function testComparableDataFailure()
     {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('The computed data is not an array, "string" given');
+
         $snapshot = new Snapshot(['data' => 'foo']);
         $snapshot->getComparableData();
     }
@@ -53,32 +53,29 @@ public function existsProvider()
                 ['bar', false]];
     }
 
-    /**
-     * @expectedException        BadMethodCallException
-     * @expectedExceptionMessage A snapshot is frozen by nature
-     */
     public function testOffsetUnset()
     {
+        $this->expectException(BadMethodCallException::class);
+        $this->expectExceptionMessage('A snapshot is frozen by nature');
+
         $snapshot = new Snapshot(['data' => ['foo' => 'bar']]);
         unset($snapshot['foo']);
     }
 
-    /**
-     * @expectedException        BadMethodCallException
-     * @expectedExceptionMessage A snapshot is frozen by nature
-     */
     public function testOffsetSet()
     {
+        $this->expectException(BadMethodCallException::class);
+        $this->expectExceptionMessage('A snapshot is frozen by nature');
+
         $snapshot = new Snapshot(['data' => ['foo' => 'bar']]);
         $snapshot[] = 'foo';
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The computed data is not an array, "string" given
-     */
     public function testInvalidDataNormalizer()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('The computed data is not an array, "string" given');
+
         $snapshot = new Snapshot(['data' => 'foo']);
 
         $refl = new ReflectionMethod('Totem\\AbstractSnapshot', 'normalize');
@@ -89,7 +86,7 @@ public function testInvalidDataNormalizer()
     /** @dataProvider normalizerProvider */
     public function testNormalizer($data, $snapshotClass, $setClass = null)
     {
-        $snapshot = new Snapshot;
+        $snapshot = new Snapshot();
         $setClass = $setClass ?: 'stdClass';
 
         $dataProperty = new ReflectionProperty('Totem\\AbstractSnapshot', 'data');
@@ -110,7 +107,7 @@ public function testNormalizer($data, $snapshotClass, $setClass = null)
 
     public function normalizerProvider()
     {
-        return [[new Snapshot, 'Totem\\Snapshot', 'Totem\\Set'],
+        return [[new Snapshot(), 'Totem\\Snapshot', 'Totem\\Set'],
                 [['foo' => 'bar'], 'Totem\\Snapshot\\ArraySnapshot'],
                 [(object) ['foo' => 'bar'], 'Totem\\Snapshot\\ObjectSnapshot']];
     }
@@ -126,14 +123,15 @@ public function testCorrectSetClass()
     {
         $snapshot = new Snapshot(['data' => []]);
         $snapshot->setSetClass('Totem\\Set');
+
+        self::assertInstanceOf(Snapshot::class, $snapshot);
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage A Set Class should be instantiable and implement Totem\SetInterface
-     */
     public function testWrongSetClass()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('A Set Class should be instantiable and implement Totem\SetInterface');
+
         $snapshot = new Snapshot(['data' => []]);
         $snapshot->setSetClass('stdclass');
     }
diff --git a/test/Change/AdditionTest.php b/test/Change/AdditionTest.php
index 0715b30..e7a17d9 100644
--- a/test/Change/AdditionTest.php
+++ b/test/Change/AdditionTest.php
@@ -11,11 +11,13 @@
 
 namespace Totem\Change;
 
-class AdditionTest extends \PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class AdditionTest extends TestCase
 {
     private $change;
 
-    public function setUp()
+    protected function setUp(): void
     {
         $this->change = new Addition('new');
     }
diff --git a/test/Change/ModificationTest.php b/test/Change/ModificationTest.php
index 8520877..ba7279e 100644
--- a/test/Change/ModificationTest.php
+++ b/test/Change/ModificationTest.php
@@ -11,11 +11,13 @@
 
 namespace Totem\Change;
 
-class ModificationTest extends \PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class ModificationTest extends TestCase
 {
     private $change;
 
-    public function setUp()
+    protected function setUp(): void
     {
         $this->change = new Modification('old', 'new');
     }
diff --git a/test/Change/RemovalTest.php b/test/Change/RemovalTest.php
index 079dba5..cf7474d 100644
--- a/test/Change/RemovalTest.php
+++ b/test/Change/RemovalTest.php
@@ -11,11 +11,13 @@
 
 namespace Totem\Change;
 
-class RemovalTest extends \PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class RemovalTest extends TestCase
 {
     private $change;
 
-    public function setUp()
+    protected function setUp(): void
     {
         $this->change = new Removal('old');
     }
diff --git a/test/SetTest.php b/test/SetTest.php
index 65cc3c1..1875a45 100644
--- a/test/SetTest.php
+++ b/test/SetTest.php
@@ -11,22 +11,23 @@
 
 namespace Totem;
 
+use BadMethodCallException;
+use OutOfBoundsException;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
 use stdClass;
-
-use PHPUnit_Framework_TestCase;
-
 use Totem\Snapshot\ArraySnapshot;
 use Totem\Snapshot\ObjectSnapshot;
 use Totem\Snapshot\CollectionSnapshot;
 
-class SetTest extends \PHPUnit_Framework_TestCase
+class SetTest extends TestCase
 {
     /**
      * @dataProvider invalidEntryProvider
      */
     public function testSetChangesWithChangedStructure($old, $new, $class)
     {
-        $set = new Set;
+        $set = new Set();
         $set->compute(new Snapshot(['data' => $old]), new Snapshot(['data' => $new]));
 
         $this->assertInstanceOf('Totem\\Change\\' . $class, $set->getChange('1'));
@@ -43,7 +44,7 @@ public function testHasChanged()
         $old = new Snapshot(['data' => ['foo' => 'bar', 'baz' => 'fubar']]);
         $new = new Snapshot(['data' => ['foo' => 'bar', 'baz' => 'fubaz']]);
 
-        $set = new Set;
+        $set = new Set();
         $set->compute($old, $new);
 
         $this->assertFalse($set->hasChanged('foo'));
@@ -52,14 +53,13 @@ public function testHasChanged()
         $this->assertTrue(isset($set['baz']));
     }
 
-    /**
-     * @expectedException OutOfBoundsException
-     */
     public function testGetChangeWithInvalidProperty()
     {
+        $this->expectException(OutOfBoundsException::class);
+
         $old = new Snapshot(['data' => ['foo' => 'bar']]);
 
-        $set = new Set;
+        $set = new Set();
         $set->compute($old, $old);
 
         $set->getChange('foo');
@@ -68,7 +68,7 @@ public function testGetChangeWithInvalidProperty()
     // @todo to break up
     public function testGetChange()
     {
-        $o = [new stdClass, (object) ['foo' => 'bar']];
+        $o = [new stdClass(), (object) ['foo' => 'bar']];
 
         $old = $new = ['foo'    => 'foo',
                        'bar'    => new ArraySnapshot(['foo', 'bar']),
@@ -92,7 +92,7 @@ public function testGetChange()
         $new['kludge'] = 42;
         $new['xyzzy']  = (object) [];
 
-        $set = new Set;
+        $set = new Set();
         $set->compute(new Snapshot(['data' => $old]), new Snapshot(['data' => $new]));
 
         $this->assertInstanceOf('Totem\\Change\\Modification', $set->getChange('fuqux'));
@@ -107,63 +107,58 @@ public function testGetChange()
 
     public function testIterator()
     {
-        $set = new Set;
+        $set = new Set();
         $set->compute(new Snapshot(['data' => ['foo']]), new Snapshot(['data' => ['bar']]));
 
         $this->assertInstanceOf('ArrayIterator', $set->getIterator());
     }
 
-    /**
-     * @expectedException BadMethodCallException
-     */
     public function testForbidenSetter()
     {
-        $set = new Set;
-        $old = new Snapshot;
+        $this->expectException(BadMethodCallException::class);
+
+        $set = new Set();
+        $old = new Snapshot();
         $set->compute($old, $old);
 
         $set[] = 'baz';
     }
 
-    /**
-     * @expectedException BadMethodCallException
-     */
     public function testForbidenUnsetter()
     {
-        $set = new Set;
-        $old = new Snapshot;
+        $this->expectException(BadMethodCallException::class);
+
+        $set = new Set();
+        $old = new Snapshot();
         $set->compute($old, $old);
 
         unset($set[0]);
     }
 
-    /**
-     * @expectedException         RuntimeException
-     * @expectedExceptionMessage  The changeset was not computed yet !
-     */
     public function testHasChangedNotComputedShouldThrowException()
     {
-        $set = new Set;
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('The changeset was not computed yet !');
+
+        $set = new Set();
         $set->hasChanged('foo');
     }
 
-    /**
-     * @expectedException         RuntimeException
-     * @expectedExceptionMessage  The changeset was not computed yet !
-     */
     public function testNotComputedCountShouldThrowException()
     {
-        $set = new Set;
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('The changeset was not computed yet !');
+
+        $set = new Set();
         count($set);
     }
 
-    /**
-     * @expectedException         RuntimeException
-     * @expectedExceptionMessage  The changeset was not computed yet !
-     */
     public function testNotComputedIteratorShouldThrowException()
     {
-        $set = new Set;
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('The changeset was not computed yet !');
+
+        $set = new Set();
         $set->getIterator();
     }
 
@@ -190,7 +185,7 @@ public function testComputeCollections()
         $old = new CollectionSnapshot($old, '[foo]');
         $new = new CollectionSnapshot($new, '[foo]');
 
-        $set = new Set;
+        $set = new Set();
         $set->compute($old, $new);
 
         $this->assertContainsOnly('integer', array_keys(iterator_to_array($set)));
@@ -199,7 +194,7 @@ public function testComputeCollections()
     /** @dataProvider unaffectedSnapshotComputerProvider */
     public function testUnaffectedCollections(AbstractSnapshot $origin, AbstractSnapshot $upstream)
     {
-        $set = new Set;
+        $set = new Set();
         $set->compute($origin, $upstream);
 
         $this->assertNotContainsOnly('integer',array_keys(iterator_to_array($set)));
diff --git a/test/Snapshot/ArraySnapshotTest.php b/test/Snapshot/ArraySnapshotTest.php
index c640368..091d742 100644
--- a/test/Snapshot/ArraySnapshotTest.php
+++ b/test/Snapshot/ArraySnapshotTest.php
@@ -11,12 +11,9 @@
 
 namespace Totem\Snapshot;
 
-use stdClass;
-use ReflectionMethod;
+use PHPUnit\Framework\TestCase;
 
-use PHPUnit_Framework_TestCase;
-
-class ArraySnapshotTest extends PHPUnit_Framework_TestCase
+class ArraySnapshotTest extends TestCase
 {
     /**
      * @dataProvider providerCompare
@@ -42,6 +39,8 @@ public function providerCompare()
      */
     public function testDeepConstructor($value)
     {
+        $this->expectNotToPerformAssertions();
+
         new ArraySnapshot(['foo' => $value]);
     }
 
diff --git a/test/Snapshot/CollectionSnapshotTest.php b/test/Snapshot/CollectionSnapshotTest.php
index fa6e9f7..f0a5313 100644
--- a/test/Snapshot/CollectionSnapshotTest.php
+++ b/test/Snapshot/CollectionSnapshotTest.php
@@ -12,38 +12,40 @@
 namespace Totem\Snapshot;
 
 use ArrayObject;
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
 use ReflectionProperty;
 
-use PHPUnit_Framework_TestCase;
-
-class CollectionSnapshotTest extends PHPUnit_Framework_TestCase
+class CollectionSnapshotTest extends TestCase
 {
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage An array or a Traversable was expected to take a snapshot of a collection, "string" given
-     */
     public function testSnapshotNotArray()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'An array or a Traversable was expected to take a snapshot of a collection, "string" given'
+        );
+
         new CollectionSnapshot('foo', 'bar', ['snapshotClass' => 'Totem\\Snapshot']);
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The snapshot class "Totem\Fubar" does not seem to be loadable
-     */
     public function testSnapshotClassNotLoadable()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('The snapshot class "Totem\Fubar" does not seem to be loadable');
+
         new CollectionSnapshot('foo', 'bar', ['snapshotClass' => 'Totem\\Fubar']);
     }
 
     /**
      * @dataProvider snapshotClassWrongReflectionProvider
-     *
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage A Snapshot Class should be instantiable and extends abstract class Totem\AbstractSnapshot
      */
     public function testSnapshotWrongReflection($class)
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'A Snapshot Class should be instantiable and extends abstract class Totem\AbstractSnapshot'
+        );
+
         new CollectionSnapshot('foo', 'bar', ['snapshotClass' => $class]);
     }
 
@@ -53,21 +55,23 @@ public function snapshotClassWrongReflectionProvider()
                 ['stdClass']];
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The given array / Traversable is not a collection as it contains non numeric keys
-     */
     public function testNonCollection()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'The given array / Traversable is not a collection as it contains non numeric keys'
+        );
+
         new CollectionSnapshot(new ArrayObject(['foo' => 'bar']), 'bar');
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The key "baz" is not defined or readable in one of the elements of the collection
-     */
     public function testKeyNotReadable()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'The key "baz" is not defined or readable in one of the elements of the collection'
+        );
+
         new CollectionSnapshot([['foo' => 'bar']], 'baz');
     }
 
@@ -97,12 +101,11 @@ public function allValidProvider()
                 [false]];
     }
 
-    /**
-     * @expectedException        InvalidArgumentException
-     * @expectedExceptionMessage The primary key "baz" is not in the computed dataset
-     */
     public function testOriginalKeyNotFound()
     {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('The primary key "baz" is not in the computed dataset');
+
         $snapshot = new CollectionSnapshot([['foo' => 'bar']], '[foo]');
         $snapshot->getOriginalKey('baz');
     }
diff --git a/test/Snapshot/ObjectSnapshotTest.php b/test/Snapshot/ObjectSnapshotTest.php
index fbaf2f1..8f84db5 100644
--- a/test/Snapshot/ObjectSnapshotTest.php
+++ b/test/Snapshot/ObjectSnapshotTest.php
@@ -11,12 +11,11 @@
 
 namespace Totem\Snapshot;
 
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
 use stdClass;
-use ReflectionMethod;
 
-use PHPUnit_Framework_TestCase;
-
-class ObjectSnapshotTest extends PHPUnit_Framework_TestCase
+class ObjectSnapshotTest extends TestCase
 {
     /**
      * @dataProvider providerCompare
@@ -29,7 +28,7 @@ public function testCompare($object, $compare, $expect)
 
     public function providerCompare()
     {
-        $object = new stdClass;
+        $object = new stdClass();
 
         $snapshot = $this->getMockBuilder('Totem\\AbstractSnapshot')
                          ->disableOriginalConstructor()
@@ -40,11 +39,10 @@ public function providerCompare()
                 [$object, $snapshot, false]];
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testConstructWithoutObject()
     {
+        $this->expectException(InvalidArgumentException::class);
+
         new ObjectSnapshot([]);
     }
 
@@ -96,4 +94,3 @@ public function __construct($foo, $bar, $baz)
     }
 }
 
-