diff --git a/.travis.yml b/.travis.yml
index 719a48e..0457012 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,8 @@ php:
   - 5.5
   - 5.6
   - 7.0
+  - 7.1
+  - 7.2
   - hhvm
 
 sudo: false
diff --git a/composer.json b/composer.json
index 8909521..56eab7d 100644
--- a/composer.json
+++ b/composer.json
@@ -21,6 +21,9 @@
         "phpunit/phpunit": "^4.0|^5.0",
         "satooshi/php-coveralls": "^0.6"
     },
+    "suggest": {
+        "ext-gmp": "It can speed up the image hash."
+    },
     "autoload": {
         "psr-4": {
             "Jenssegers\\ImageHash\\": "src"
diff --git a/phpunit.xml b/phpunit.xml
index ac0af93..e828ed2 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -14,4 +14,9 @@
             <directory>./tests/</directory>
         </testsuite>
     </testsuites>
+    <filter>
+        <whitelist addUncoveredFilesFromWhitelist="false">
+            <directory suffix=".php">src/</directory>
+        </whitelist>
+    </filter>
 </phpunit>
diff --git a/tests/ImageHashTest.php b/tests/ImageHashTest.php
index 784f8ae..0248984 100644
--- a/tests/ImageHashTest.php
+++ b/tests/ImageHashTest.php
@@ -1,8 +1,9 @@
 <?php
 
 use Jenssegers\ImageHash\ImageHash;
+use PHPUnit\Framework\TestCase;
 
-class ImageHashTest extends PHPUnit_Framework_TestCase
+class ImageHashTest extends TestCase
 {
     /**
      * @var ImageHash
@@ -16,11 +17,7 @@ public function setup()
 
     public function testHashStringInvalidFile()
     {
-        if (method_exists($this, 'expectException')) {
-            $this->expectException('InvalidArgumentException');
-        } else {
-            $this->setExpectedException('InvalidArgumentException');
-        }
+        $this->setExpectedException('InvalidArgumentException');
 
         $this->imageHash->hashFromString('nonImageString');
     }
diff --git a/tests/ImageTest.php b/tests/ImageTest.php
index 3916d61..4dad507 100644
--- a/tests/ImageTest.php
+++ b/tests/ImageTest.php
@@ -5,8 +5,9 @@
 use Jenssegers\ImageHash\Implementations\AverageHash;
 use Jenssegers\ImageHash\Implementations\DifferenceHash;
 use Jenssegers\ImageHash\Implementations\PerceptualHash;
+use PHPUnit\Framework\TestCase;
 
-class ImageTest extends PHPUnit_Framework_TestCase
+class ImageTest extends TestCase
 {
     /**
      * @var Implementation[]
@@ -154,12 +155,4 @@ public function testDecimalMode()
         $this->assertTrue(is_int($hash), $hash);
         $this->assertEquals(0, $imageHash->distance($hash, $hash));
     }
-
-    // public function testThrowsUnexceptedValueException()
-    // {
-    //     $this->setExpectedException('UnexpectedValueException');
-
-    //     $imageHash = new ImageHash;
-    //     $imageHash->distance("a", "b");
-    // }
 }