Tweaking distros

.travis.yml

@@ -7,26 +7,35 @@ matrix:
     - php: 5.3
       dist: precise
     - php: 5.4
+      dist: trusty
     - php: 5.5
+      dist: trusty
     - php: 5.6
+      dist: trusty
     - php: 7.0
+      dist: xenial
     - php: 7.1
     - php: 7.2
     - php: 7.3
     - php: hhvm
-      env: HHVM=true
+      dist: trusty
+      env: PHPUNIT=5.7
 
 install:
   - composer install
-  - if [[ $HHVM == true ]]; then composer require "phpunit/phpunit:5.7"; fi
+  - if [[ $PHPUNIT == 5.7 ]]; then composer require "phpunit/phpunit:5.7"; fi
 
 before_script:
   - mkdir -p build/logs
   - cd tests
 
 script:
-  - if [[ $HHVM == true ]]; then ../vendor/bin/phpunit --colors --coverage-clover ../build/logs/clover.xml .; fi
-  - if [[ $HHVM != true ]]; then phpunit --colors --coverage-clover ../build/logs/clover.xml .; fi
+  - |
+    if [[ $PHPUNIT57 == 5.7 ]]; then
+      ../vendor/bin/phpunit --colors --coverage-clover ../build/logs/clover.xml .
+    else
+      phpunit --colors --coverage-clover ../build/logs/clover.xml .
+    fi
 
 after_success:
   - cd ..