xvfb needs to be started in before_script

.travis.yml

@@ -66,6 +66,9 @@ before_script:
       bash tests/bin/install.sh woocommerce_test root '' localhost $WP_VERSION
       composer global require "phpunit/phpunit=5.7.*|7.5.*"
     fi
+  - export DISPLAY=:99.0
+  - sh -e /etc/init.d/xvfb start
+  - sleep 3 # give xvfb some time to start
 
 script:
   - bash tests/bin/phpunit.sh

tests/bin/run-e2e-CI.sh

@@ -3,11 +3,8 @@ if [[ ${RUN_E2E} == 1 ]]; then
 
 	WP_SITE_URL="http://localhost:8080"
 
-	# Start xvfb to run the tests
+	# Set base url to that of e2e test suite.
 	export BASE_URL="$WP_SITE_URL"
-	export DISPLAY=:99.0
-	sh -e /etc/init.d/xvfb start
-	sleep 3
 
 	# Run the tests
 	npm test