Merge pull request #10 from joaorobertopb/patch-6

Fixes issue #9

Author: Renato Marinho

.travis.yml

@@ -1,6 +1,8 @@
 language: php
 # list any PHP version you want to test against
 php:
+  - 5.6
+  - 7.0
   - 7.1
 before_script:
   - composer self-update

composer.json

@@ -20,7 +20,7 @@
     "illuminate/support": "5.3.x|5.4.x|5.5.x"
   },
   "require-dev": {
-    "phpunit/phpunit": "^6.2",
+    "phpunit/phpunit": "~5.7",
     "orchestra/testbench": "~3.2",
     "squizlabs/php_codesniffer": "^2.3"
   },