diff --git a/.travis.yml b/.travis.yml
index ca9897f..1a2cfe0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,5 @@
-sudo: false
-
 language: php
+
 php:
   - hhvm
   - 7
@@ -11,7 +10,7 @@ before_script:
 
 script:
   - mkdir -p build/logs
-  - phpunit -c tests/phpunit.xml --coverage-clover build/logs/clover.xml tests
+  - php vendor/bin/phpunit -c tests/phpunit.xml --coverage-clover build/logs/clover.xml tests
 
 after_script:
   - php ./vendor/bin/coveralls -v
diff --git a/composer.json b/composer.json
index e81b53c..d76cd49 100644
--- a/composer.json
+++ b/composer.json
@@ -12,11 +12,16 @@
         "sebastian/diff": "^1.4"
     },
     "require-dev": {
-        "phpunit/phpunit": "5.4.*"
+        "phpunit/phpunit": "^5.5"
     },
     "autoload": {
         "psr-4": {
             "Sokil\\Diff\\": "src/"
         }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Sokil\\Diff\\": "tests/"
+        }
     }
 }
diff --git a/src/Change.php b/src/Change.php
index 4c5d2f2..6c978aa 100644
--- a/src/Change.php
+++ b/src/Change.php
@@ -39,4 +39,4 @@ public function getNewValue()
     {
         return $this->newValue;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Renderer.php b/src/Renderer.php
index dc135ae..d094ed0 100644
--- a/src/Renderer.php
+++ b/src/Renderer.php
@@ -130,4 +130,4 @@ public function render(Change $change)
         // build diff
         return implode(PHP_EOL, $diff);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/RendererTest.php b/tests/RendererTest.php
index 43bd098..a9388a4 100644
--- a/tests/RendererTest.php
+++ b/tests/RendererTest.php
@@ -2,7 +2,9 @@
 
 namespace Sokil\Diff;
 
-class RendererTest extends \PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class RendererTest extends TestCase
 {
     public function renderChangeDataProvider()
     {
@@ -117,4 +119,26 @@ public function testRender_ChangeValueHasStringType(
         $this->assertEquals($expectedDiff, $actualDiff);
     }
 
-}
\ No newline at end of file
+    /**
+     * @expectedException        \InvalidArgumentException
+     * @expectedExceptionMessage Invalid format specified
+     */
+    public function testSetFormatWithInvalidType()
+    {
+        $diffRenderer = new Renderer([]);
+
+        $diffRenderer->setFormat('not_array_type');
+    }
+
+    /**
+     * @expectedException        \InvalidArgumentException
+     * @expectedExceptionMessage Invalid format specified
+     */
+    public function testSetFormatWithInvalidDefinedFormats()
+    {
+        $diffRenderer = new Renderer([]);
+
+        $diffRenderer->setFormat(1000);
+    }
+
+}
diff --git a/tests/phpunit.xml b/tests/phpunit.xml
index 4150acd..9ee752e 100644
--- a/tests/phpunit.xml
+++ b/tests/phpunit.xml
@@ -2,7 +2,12 @@
 <phpunit colors="true" bootstrap="../vendor/autoload.php">
     <testsuites>
         <testsuite name="AllTests">
-            <directory>.</directory>
+            <directory>./</directory>
         </testsuite>
     </testsuites>
-</phpunit>
\ No newline at end of file
+     <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">../src</directory>
+        </whitelist>
+    </filter>
+</phpunit>