Testing Travis config variables

.travis.yml

@@ -1,11 +1,19 @@
 language: php
 php:
+  - '5.6'
   - '7.0'
   - '7.1'
+matrix:
+  allow_failures:
+    - php: 5.6
+  fast_finish: true
 cache:
   directories:
     - $HOME/.composer/cache/files
 before_script:
+  - echo $TRAVIS_PHP_VERSION
+  - phpenv global "$TRAVIS_PHP_VERSION"
+  - composer config extra.platform.php $TRAVIS_PHP_VERSION
   - composer require php-coveralls/php-coveralls
   - composer install
 script: