diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..0b0f784
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,12 @@
+language: php
+php:
+  - '5.4'
+  - '5.5'
+  - '5.6'
+  - '7.0'
+  - hhvm
+  - nightly
+notifications:
+  email: false
+  
+  
diff --git a/app/libraries/Calculator.php b/app/libraries/Calculator.php
index 3fd2190..bfb0c9b 100644
--- a/app/libraries/Calculator.php
+++ b/app/libraries/Calculator.php
@@ -8,4 +8,29 @@ public function add($x, $y)
     }
     return $x + $y;
   }
-}
\ No newline at end of file
+
+  public function sub($x, $y)
+  {
+    if ( !is_numeric($x) || !is_numeric($y) ) {
+      throw new \InvalidArgumentException;
+    }
+    return $x - $y;
+  }
+
+  public function mul($x, $y)
+  {
+    if ( !is_numeric($x) || !is_numeric($y) ) {
+      throw new \InvalidArgumentException;
+    }
+    return $x * $y;
+  }
+
+  public function div($x, $y)
+  {
+    if ( !is_numeric($x) || !is_numeric($y) ) {
+      throw new \InvalidArgumentException;
+    }
+    return $x / $y;
+  }
+
+}
diff --git a/phpunit.xml b/phpunit.xml
index b8361cd..8be99e9 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,16 +1,20 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php"
+<phpunit 
+         bootstrap="vendor/autoload.php"
          colors="true"
          convertErrorsToExceptions="true"
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
          processIsolation="false"
          stopOnFailure="false"
-         syntaxCheck="false"
+         stopOnIncomplete="false"
+         stopOnSkipped="false"
+         stopOnRisky="false"
+         syntaxCheck="true"
 >
     <testsuites>
         <testsuite name="App Tests">
             <directory>test</directory>
         </testsuite>
     </testsuites>
-</phpunit>
\ No newline at end of file
+</phpunit>
diff --git a/readme.md b/readme.md
new file mode 100644
index 0000000..3ae0bec
--- /dev/null
+++ b/readme.md
@@ -0,0 +1 @@
+[![Build Status](https://travis-ci.org/nimasdj/PHPUnit-Workflow.svg?branch=master)](https://travis-ci.org/nimasdj/PHPUnit-Workflow)
diff --git a/test/CalculatorTest.php b/test/CalculatorTest.php
index 6e5dff9..ea25ed2 100644
--- a/test/CalculatorTest.php
+++ b/test/CalculatorTest.php
@@ -9,7 +9,7 @@ public function setUp()
     $this->calculator = new Calculator;
   }
 
-  public function inputNumbers()
+  public function addNumbers()
   {
     return [
       [2, 2, 4],
@@ -18,19 +18,70 @@ public function inputNumbers()
   }
 
   /**
-   * @dataProvider inputNumbers
+   * @dataProvider addNumbers
    */
   public function testCanAddNumbers($x, $y, $sum)
   {
     $this->assertEquals($sum, $this->calculator->add($x, $y));
   }
 
+ public function subNumbers()
+  {
+    return [
+      [4, 2, 2],
+      [2, 4, -2]
+    ];
+  }
+
+  /**
+   * @dataProvider subNumbers
+   */
+  public function testCanSubNumbers($x, $y, $sum)
+  {
+    $this->assertEquals($sum, $this->calculator->sub($x, $y));
+  }
+
+ public function mulNumbers()
+  {
+    return [
+      [4, 2, 8],
+      [4, 4, 16]
+    ];
+  }
+
   /**
+   * @dataProvider mulNumbers
+   */
+  public function testCanMulNumbers($x, $y, $sum)
+  {
+    $this->assertEquals($sum, $this->calculator->mul($x, $y));
+  }
+
+ public function divNumbers()
+  {
+    return [
+      [4, 2, 2],
+      [8, 2, 4] 
+    ];
+  }
+
+  /**
+   * @dataProvider divNumbers
+   */
+  public function testCanDivNumbers($x, $y, $sum)
+  {
+    $this->assertEquals($sum, $this->calculator->div($x, $y));
+  }
+
+    /**
     * @expectedException InvalidArgumentException
     */
   public function testThrowsExceptionIfNonNumberIsPassed()
   {
-    $calc = new Calculator;
-    $calc->add('a', 'b');
+    $this->calculator->add('a', 'b');
+    $this->calculator->sub('a', 'b');
+    $this->calculator->mul('a', 'b');
+    $this->calculator->div('a', 'b');
   }
-}
\ No newline at end of file
+
+}