minor #5 Compatibility with PHPUnit 6 (Lctrs)

This PR was squashed before being merged into the 2.1.x-dev branch (closes #5).

Discussion
----------

Compatibility with PHPUnit 6

Commits
-------

e71829e Compatibility with PHPUnit 6

Author: xabbuh

.travis.yml

@@ -23,12 +23,13 @@ matrix:
 before_install:
   - if [[ "$TRAVIS_PHP_VERSION" != "hhvm" && "$xdebug" != "yes" ]]; then phpenv config-rm xdebug.ini; fi
   - composer self-update
+  - composer require 'phpunit/phpunit:^4.8.35|^5.4.3|^6.0' --dev --no-update
 
 install:
   - if [ "$deps" = "low" ]; then composer update --prefer-lowest --prefer-stable; else composer install; fi
 
 script:
   - vendor/bin/phpspec run
-  - if [[ "$xdebug" = "yes" ]]; then phpunit --coverage-clover=coverage.clover; else phpunit; fi
+  - if [[ "$xdebug" = "yes" ]]; then vendor/bin/phpunit --coverage-clover=coverage.clover; else vendor/bin/phpunit; fi
   - if [[ "$xdebug" = "yes" ]]; then wget https://scrutinizer-ci.com/ocular.phar; fi
   - if [[ "$xdebug" = "yes" ]]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi

composer.json

@@ -14,7 +14,7 @@
     "require": {
         "php": ">=5.3.0",
         "php-xapi/model": "^1.0 || ^2.0",
-        "php-xapi/serializer": "^2.0",
+        "php-xapi/serializer": "^2.1.1",
         "symfony/serializer": "~2.8|~3.0"
     },
     "require-dev": {

tests/SerializerTest.php

@@ -11,7 +11,7 @@
 
 namespace Xabbuh\XApi\Serializer\Symfony\Tests;
 
-use Symfony\Component\Serializer\SerializerInterface;
+use PHPUnit\Framework\TestCase;
 use Xabbuh\XApi\Model\Account;
 use Xabbuh\XApi\Model\Activity;
 use Xabbuh\XApi\Model\Actor;
@@ -28,7 +28,7 @@
 use Xabbuh\XApi\Model\Verb;
 use Xabbuh\XApi\Serializer\Symfony\Serializer;
 
-class SerializerTest extends \PHPUnit_Framework_TestCase
+class SerializerTest extends TestCase
 {
     private $serializer;