Configure Travis to test different versions of SF and PHPUnit

Author: matthiasnoback

.travis.yml

@@ -6,7 +6,19 @@ php:
   - 5.5
   - 5.6
 
-before_script: composer install --dev
+env:
+  - SYMFONY_VERSION=2.5.* PHPUNIT_VERSION=~3.7
+  - SYMFONY_VERSION=2.0.* PHPUNIT_VERSION=~4.0
+  - SYMFONY_VERSION=2.1.* PHPUNIT_VERSION=~4.0
+  - SYMFONY_VERSION=2.2.* PHPUNIT_VERSION=~4.0
+  - SYMFONY_VERSION=2.3.* PHPUNIT_VERSION=~4.0
+  - SYMFONY_VERSION=2.4.* PHPUNIT_VERSION=~4.0
+  - SYMFONY_VERSION=2.5.* PHPUNIT_VERSION=~4.0
+
+before_script:
+  - composer require --no-update "symfony/config:${SYMFONY_VERSION}"
+  - composer require --no-update "phpunit/phpunit:${PHPUNIT_VERSION}"
+  - composer update
 
 notifications:
   email: [email protected]