diff --git a/composer.lock b/composer.lock
index c778e2d..d9af61f 100644
--- a/composer.lock
+++ b/composer.lock
@@ -484,12 +484,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/FriendsOfPHP/PHP-CS-Fixer.git",
-                "reference": "6a18fd75962f12db61384991797ba7c99de19bf4"
+                "reference": "7f8dd8a93eb89d87de39e04ca9c284c60e1ef807"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/6a18fd75962f12db61384991797ba7c99de19bf4",
-                "reference": "6a18fd75962f12db61384991797ba7c99de19bf4",
+                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/7f8dd8a93eb89d87de39e04ca9c284c60e1ef807",
+                "reference": "7f8dd8a93eb89d87de39e04ca9c284c60e1ef807",
                 "shasum": ""
             },
             "require": {
@@ -556,6 +556,7 @@
                     "tests/Test/IntegrationCaseFactoryInterface.php",
                     "tests/Test/InternalIntegrationCaseFactory.php",
                     "tests/Test/IsIdenticalConstraint.php",
+                    "tests/Test/TokensWithObservedTransformers.php",
                     "tests/TestCase.php"
                 ]
             },
@@ -584,7 +585,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-02-18T17:03:44+00:00"
+            "time": "2021-03-03T16:08:57+00:00"
         },
         {
             "name": "myclabs/deep-copy",
@@ -2578,16 +2579,16 @@
         },
         {
             "name": "symfony/console",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "89d4b176d12a2946a1ae4e34906a025b7b6b135a"
+                "reference": "d6d0cc30d8c0fda4e7b213c20509b0159a8f4556"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/89d4b176d12a2946a1ae4e34906a025b7b6b135a",
-                "reference": "89d4b176d12a2946a1ae4e34906a025b7b6b135a",
+                "url": "https://api.github.com/repos/symfony/console/zipball/d6d0cc30d8c0fda4e7b213c20509b0159a8f4556",
+                "reference": "d6d0cc30d8c0fda4e7b213c20509b0159a8f4556",
                 "shasum": ""
             },
             "require": {
@@ -2655,7 +2656,7 @@
                 "terminal"
             ],
             "support": {
-                "source": "https://github.com/symfony/console/tree/v5.2.3"
+                "source": "https://github.com/symfony/console/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -2671,7 +2672,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-28T22:06:19+00:00"
+            "time": "2021-02-23T10:08:49+00:00"
         },
         {
             "name": "symfony/deprecation-contracts",
@@ -2742,16 +2743,16 @@
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/event-dispatcher.git",
-                "reference": "4f9760f8074978ad82e2ce854dff79a71fe45367"
+                "reference": "d08d6ec121a425897951900ab692b612a61d6240"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/4f9760f8074978ad82e2ce854dff79a71fe45367",
-                "reference": "4f9760f8074978ad82e2ce854dff79a71fe45367",
+                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/d08d6ec121a425897951900ab692b612a61d6240",
+                "reference": "d08d6ec121a425897951900ab692b612a61d6240",
                 "shasum": ""
             },
             "require": {
@@ -2807,7 +2808,7 @@
             "description": "Provides tools that allow your application components to communicate with each other by dispatching events and listening to them",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/event-dispatcher/tree/v5.2.3"
+                "source": "https://github.com/symfony/event-dispatcher/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -2823,7 +2824,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-27T10:36:42+00:00"
+            "time": "2021-02-18T17:12:37+00:00"
         },
         {
             "name": "symfony/event-dispatcher-contracts",
@@ -2906,16 +2907,16 @@
         },
         {
             "name": "symfony/filesystem",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "262d033b57c73e8b59cd6e68a45c528318b15038"
+                "reference": "710d364200997a5afde34d9fe57bd52f3cc1e108"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/262d033b57c73e8b59cd6e68a45c528318b15038",
-                "reference": "262d033b57c73e8b59cd6e68a45c528318b15038",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/710d364200997a5afde34d9fe57bd52f3cc1e108",
+                "reference": "710d364200997a5afde34d9fe57bd52f3cc1e108",
                 "shasum": ""
             },
             "require": {
@@ -2948,7 +2949,7 @@
             "description": "Provides basic utilities for the filesystem",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/filesystem/tree/v5.2.3"
+                "source": "https://github.com/symfony/filesystem/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -2964,20 +2965,20 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-27T10:01:46+00:00"
+            "time": "2021-02-12T10:38:38+00:00"
         },
         {
             "name": "symfony/finder",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
-                "reference": "4adc8d172d602008c204c2e16956f99257248e03"
+                "reference": "0d639a0943822626290d169965804f79400e6a04"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/finder/zipball/4adc8d172d602008c204c2e16956f99257248e03",
-                "reference": "4adc8d172d602008c204c2e16956f99257248e03",
+                "url": "https://api.github.com/repos/symfony/finder/zipball/0d639a0943822626290d169965804f79400e6a04",
+                "reference": "0d639a0943822626290d169965804f79400e6a04",
                 "shasum": ""
             },
             "require": {
@@ -3009,7 +3010,7 @@
             "description": "Finds files and directories via an intuitive fluent interface",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/finder/tree/v5.2.3"
+                "source": "https://github.com/symfony/finder/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -3025,11 +3026,11 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-28T22:06:19+00:00"
+            "time": "2021-02-15T18:55:04+00:00"
         },
         {
             "name": "symfony/options-resolver",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/options-resolver.git",
@@ -3078,7 +3079,7 @@
                 "options"
             ],
             "support": {
-                "source": "https://github.com/symfony/options-resolver/tree/v5.2.3"
+                "source": "https://github.com/symfony/options-resolver/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -3728,7 +3729,7 @@
         },
         {
             "name": "symfony/process",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/process.git",
@@ -3770,7 +3771,7 @@
             "description": "Executes commands in sub-processes",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/process/tree/v5.2.3"
+                "source": "https://github.com/symfony/process/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -3869,7 +3870,7 @@
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
@@ -3911,7 +3912,7 @@
             "description": "Provides a way to profile code",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/stopwatch/tree/v5.2.3"
+                "source": "https://github.com/symfony/stopwatch/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -3931,16 +3932,16 @@
         },
         {
             "name": "symfony/string",
-            "version": "v5.2.3",
+            "version": "v5.2.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/string.git",
-                "reference": "c95468897f408dd0aca2ff582074423dd0455122"
+                "reference": "4e78d7d47061fa183639927ec40d607973699609"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/string/zipball/c95468897f408dd0aca2ff582074423dd0455122",
-                "reference": "c95468897f408dd0aca2ff582074423dd0455122",
+                "url": "https://api.github.com/repos/symfony/string/zipball/4e78d7d47061fa183639927ec40d607973699609",
+                "reference": "4e78d7d47061fa183639927ec40d607973699609",
                 "shasum": ""
             },
             "require": {
@@ -3994,7 +3995,7 @@
                 "utf8"
             ],
             "support": {
-                "source": "https://github.com/symfony/string/tree/v5.2.3"
+                "source": "https://github.com/symfony/string/tree/v5.2.4"
             },
             "funding": [
                 {
@@ -4010,7 +4011,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-25T15:14:59+00:00"
+            "time": "2021-02-16T10:20:28+00:00"
         },
         {
             "name": "theseer/tokenizer",
diff --git a/src/Collection.php b/src/Collection.php
index dfecee6..1930111 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -55,7 +55,7 @@ class Collection implements
      * @param int $modifier
      * @param int $multiplier
      */
-    public function __construct(int $amount, int $sides, int $modifier, int $multiplier)
+    public function __construct(int $amount, int $sides, int $modifier = 1, int $multiplier = 1)
     {
         if ($amount < 1) {
             throw new OutOfRangeException('A collection must have at least one dice.');
diff --git a/tests/src/Unit/CupTest.php b/tests/src/Unit/CupTest.php
new file mode 100644
index 0000000..0aee306
--- /dev/null
+++ b/tests/src/Unit/CupTest.php
@@ -0,0 +1,127 @@
+<?php
+/*
+ * This file is part of the LuckByDice package.
+ *
+ * (c) 2017-2021 Ouxsoft  <contact@ouxsoft.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Ouxsoft\LivingMarkup\Tests\Unit;
+
+use Ouxsoft\LuckByDice\Cup;
+use Ouxsoft\LuckByDice\Collection;
+use PHPUnit\Framework\TestCase;
+
+class CupTest extends TestCase
+{
+    private $cup;
+
+    public function setUp(): void
+    {
+        $this->cup = new Cup();
+        $this->cup[] = new Collection(1, 6, 1, 1);
+        $this->cup[] = new Collection(1, 8, 1, 1);
+    }
+
+    public function tearDown(): void
+    {
+        unset($this->cup);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::offsetExists
+     */
+    public function testOffsetExists()
+    {
+        $this->assertTrue($this->cup->offsetExists(1));
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::offsetGet
+     */
+    public function testOffsetGet()
+    {
+        $collection = new Collection(1, 8, 1, 1);
+        $this->assertEquals($collection, $this->cup->offsetGet(1));
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::offsetSet
+     */
+    public function testOffsetSet()
+    {
+        $collection = new Collection(1, 8, 1, 1);
+        $this->cup[] = $collection;
+        $this->assertEquals($collection, $this->cup->offsetGet(2));
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::offsetUnset
+     */
+    public function testOffsetUnset()
+    {
+        $this->cup->offsetUnset('k');
+        $this->assertArrayNotHasKey('k', $this->cup);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::current
+     */
+    public function testCurrent()
+    {
+        $current = $this->cup->current();
+        $this->assertInstanceOf(Collection::class, $current);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::next
+     */
+    public function testNext()
+    {
+        $this->cup->next();
+        $key = $this->cup->key();
+        $this->assertEquals(1, $key);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::key
+     */
+    public function testKey()
+    {
+        $key = $this->cup->key();
+        $this->assertEquals(0, $key);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::valid
+     */
+    public function testValid()
+    {
+        $this->assertTrue($this->cup->valid());
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::rewind
+     */
+    public function testRewind()
+    {
+        $this->cup->next();
+        $this->cup->rewind();
+        $key = $this->cup->key();
+        $this->assertEquals(0, $key);
+    }
+
+    /**
+     * @covers \Ouxsoft\LuckByDice\Cup::reverse
+     */
+    public function testReverse()
+    {
+        $this->cup->reverse();
+
+        $key = $this->cup->key();
+        $this->assertEquals(0, $key);
+    }
+
+}
diff --git a/tests/src/Unit/DiceTest.php b/tests/src/Unit/DiceTest.php
index ee4dea2..01b2e6a 100644
--- a/tests/src/Unit/DiceTest.php
+++ b/tests/src/Unit/DiceTest.php
@@ -1,5 +1,4 @@
 <?php
-
 /*
  * This file is part of the LuckByDice package.
  *