drop php 5.5

added phpunit 6 support
travis update

.travis.yml

@@ -20,6 +20,9 @@ services:
 
 env:
   global:
+    - COMPOSER_ARGS="--no-interaction"
+    - COVERAGE_DEPS="satooshi/php-coveralls"
+    - LEGACY_DEPS="phpunit/phpunit"
     - TESTS_ZEND_CACHE_APC_ENABLED=true
     - TESTS_ZEND_CACHE_APCU_ENABLED=true
     - TESTS_ZEND_CACHE_FILESYSTEM_DIR=/dev/shm
@@ -47,18 +50,6 @@ env:
 
 matrix:
   include:
-    - php: 5.5
-      env:
-        - DEPS=lowest
-        - APCU_PECL_VERSION="apcu-4.0.8"
-    - php: 5.5
-      env:
-        - DEPS=locked
-        - APCU_PECL_VERSION="apcu-4.0.10"
-    - php: 5.5
-      env:
-        - DEPS=latest
-        - APCU_PECL_VERSION="apcu-4.0.11"
     - php: 5.6
       env:
         - DEPS=lowest
@@ -154,10 +145,11 @@ install:
         );
     fi
 
+  - travis_retry composer install $COMPOSER_ARGS
+  - if [[ $TRAVIS_PHP_VERSION =~ ^5.6 ]]; then travis_retry composer update $COMPOSER_ARGS --with-dependencies $LEGACY_DEPS ; fi
   - if [[ $DEPS == 'latest' ]]; then travis_retry composer update $COMPOSER_ARGS ; fi
   - if [[ $DEPS == 'lowest' ]]; then travis_retry composer update --prefer-lowest --prefer-stable $COMPOSER_ARGS ; fi
-  - if [[ $TEST_COVERAGE == 'true' ]]; then travis_retry composer require --dev $COMPOSER_ARGS satooshi/php-coveralls:^1.0 ; fi
-  - travis_retry composer install $COMPOSER_ARGS
+  - if [[ $TEST_COVERAGE == 'true' ]]; then travis_retry composer require --dev $COMPOSER_ARGS $COVERAGE_DEPS ; fi
   - composer show
 
 before_script:

composer.json

@@ -13,15 +13,15 @@
         }
     },
     "require": {
-        "php": "^5.5 || ^7.0",
+        "php": "^7.0 || ^5.6",
         "zendframework/zend-stdlib": "^2.7 || ^3.0",
         "zendframework/zend-servicemanager": "^2.7.5 || ^3.0.3",
         "zendframework/zend-eventmanager": "^2.6.2 || ^3.0"
     },
     "require-dev": {
         "zendframework/zend-serializer": "^2.6",
         "zendframework/zend-session": "^2.6.2",
-        "phpunit/phpunit": "^4.8",
+        "phpunit/phpunit": "^6.0.8 || ^5.7.15",
         "phpbench/phpbench": "^0.10.0",
         "zendframework/zend-coding-standard": "~1.0.0"
     },