add PHPUNIT test suites

.gitignore

@@ -2,3 +2,4 @@
 .idea
 node_modules
 *.o
+vendor

composer.json

@@ -0,0 +1,5 @@
+{
+    "require": {
+        "phpunit/phpunit": "5.5.*"
+    }
+}

phpunit.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<testsuites > 
+  <testsuite name="code-problom test suites">
+    <directory suffix="Test.php">tests/php</directory>
+  </testsuite>
+</testsuites>

tests/php/factorialTest.php

@@ -0,0 +1,17 @@
+<?php
+use PHPUnit\Framework\TestCase;
+
+require_once  'solutions/php/factorial.php';
+
+class StackTest extends TestCase
+{
+    public function test_factorial()
+    {
+        $this->assertEquals(1,factorial(1) );
+        $this->assertEquals(2,factorial(2) );
+        $this->assertEquals(6,factorial(3) );
+        $this->assertEquals(120,factorial(5) );
+        $this->assertEquals(2432902008176640000,factorial(20) );
+    }
+}
+?>