Travis-Ci not following PSR-4

I am trying to learn how to use Travis-CI. My first attempt is not going well.

I have a project at https://github.com/RogerCreasy/simpleJWT

Here is my .travis.yaml

language: php
php:
  - '5.4'
  - '5.5'
  - '5.6'
  - '7.0'

before_script:
  - composer self-update
  - composer install --prefer-source --no-interaction --dev

script: vendor/bin/phpunit --configuration phpunit.xml

I am using PSR-4 autoloading in my composer.json file.

 "autoload": {
 "psr-4": {
   "RogerCreasy\SimpleJWT\": "src"
   }
 },

PHPUnit tests run successfully locally. But, through Travis they fail. Travis looks for the class I am testing at the full namespace (/RogerCreasy/SimpleJWT/)

Where should I look for the problem?