fix travis config

.travis.yml

@@ -24,13 +24,40 @@ matrix:
       env: WP_VERSION=latest WP_MULTISITE=1
 
 before_script:
-  - export PATH="$HOME/.composer/vendor/bin:$PATH"
-  - |
-    if [[ ${TRAVIS_PHP_VERSION:0:2} == "7." ]]; then
-      composer global require "phpunit/phpunit=5.7.*"
-    elif [[ ${TRAVIS_PHP_VERSION:0:3} != "5.2" ]]; then
-      composer global require "phpunit/phpunit=4.8.*"
-    fi
+- |
+  # Remove Xdebug for a huge performance increase, but not from nightly or hhvm:
+  stable='^[0-9\.]+$'
+  if [[ "$TRAVIS_PHP_VERSION" =~ $stable ]]; then
+    phpenv config-rm xdebug.ini
+  fi
+- |
+  # Export Composer's global bin dir to PATH, but not on PHP 5.2:
+  if [[ ${TRAVIS_PHP_VERSION:0:3} != "5.2" ]]; then
+    composer config --list --global
+    export PATH=`composer config --list --global | grep '\[home\]' | { read a; echo "${a#* }/vendor/bin:$PATH"; }`
+  fi
+- |
+  # Install the specified version of PHPUnit depending on the PHP version:
+  if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
+    case "$TRAVIS_PHP_VERSION" in
+      7.1|7.0|hhvm|nightly)
+        echo "Using PHPUnit 5.7"
+        composer global require "phpunit/phpunit=5.7.*"
+        ;;
+      5.6|5.5|5.4|5.3)
+        echo "Using PHPUnit 4.8"
+        composer global require "phpunit/phpunit=4.8.*"
+        ;;
+      5.2)
+        # Do nothing, use default PHPUnit 3.6.x
+        echo "Using default PHPUnit, hopefully 3.6"
+        ;;
+      *)
+        echo "No PHPUnit version handling for PHP version $TRAVIS_PHP_VERSION"
+        exit 1
+        ;;
+    esac
+  fi
   - bash bin/install-wp-tests.sh wordpress root '' localhost $WP_VERSION
 
 script: phpunit