diff --git a/composer.json b/composer.json
index 7f6a744..d8d5026 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,11 @@
             "email": "arkadiusz.kondas@gmail.com"
         }
     ],
+    "autoload": {
+        "psr-4": {
+            "": "src/"
+        }
+    },
     "config": {
         "bin-dir": "bin"
     },
diff --git a/phpunit.xml b/phpunit.xml
new file mode 100644
index 0000000..d31e033
--- /dev/null
+++ b/phpunit.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+        colors="true"
+        beStrictAboutTestsThatDoNotTestAnything="true"
+        beStrictAboutOutputDuringTests="true"
+        beStrictAboutTestSize="true"
+        beStrictAboutChangesToGlobalState="true"
+>
+    <testsuites>
+        <testsuite name="PHP-ML Test Suite">
+            <directory>tests/*</directory>
+        </testsuite>
+    </testsuites>​
+</phpunit>
diff --git a/src/Phpml/Exception/InvalidArgumentException.php b/src/Phpml/Exception/InvalidArgumentException.php
index c88ab50..4ee194b 100644
--- a/src/Phpml/Exception/InvalidArgumentException.php
+++ b/src/Phpml/Exception/InvalidArgumentException.php
@@ -9,9 +9,9 @@ class InvalidArgumentException extends \Exception
     /**
      * @return InvalidArgumentException
      */
-    public static function parametersSizeNotMatch()
+    public static function sizeNotMatch()
     {
-        return new self('Size of parameters not match');
+        return new self('Size of given arguments not match');
     }
 
 }
diff --git a/src/Phpml/Metric/Distance.php b/src/Phpml/Metric/Distance.php
index e1e64c6..581b73c 100644
--- a/src/Phpml/Metric/Distance.php
+++ b/src/Phpml/Metric/Distance.php
@@ -16,11 +16,11 @@ class Distance
      *
      * @throws InvalidArgumentException
      */
-    public static function euclidean(array $a, array $b): float 
+    public static function euclidean(array $a, array $b): float
     {
         if(count($a) != count($b))
         {
-            throw InvalidArgumentException::parametersSizeNotMatch();
+            throw InvalidArgumentException::sizeNotMatch();
         }
 
         $distance = 0;
diff --git a/tests/Phpml/Metric/DistanceTest.php b/tests/Phpml/Metric/DistanceTest.php
new file mode 100644
index 0000000..947bb81
--- /dev/null
+++ b/tests/Phpml/Metric/DistanceTest.php
@@ -0,0 +1,18 @@
+<?php
+declare(strict_types = 1);
+
+namespace tests\Phpml\Metric;
+
+use Phpml\Metric\Distance;
+
+class DistanceTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @expectedException \Phpml\Exception\InvalidArgumentException
+     */
+    public function testThrowExceptionOnInvalidArguments()
+    {
+        Distance::euclidean([0, 1, 2], [0, 2]);
+    }
+
+}