try starting xvfb in different manner

Author: konserw

.travis.yml

@@ -1,4 +1,4 @@
-group: deprecated-2017Q3
+#group: deprecated-2017Q3
 
 language: cpp
 os: linux
@@ -11,6 +11,8 @@ env:
   - GMOCK_VER=1.8.0 
   - GMOCK_VER=1.7.0 
   - GMOCK_PATH=/usr/src/gmock #1.6.0 from ubuntu trusty repo
+  global:
+    - DISPLAY=:99
 matrix:
   include:
     - os: linux
@@ -42,6 +44,11 @@ addons:
       - qtbase5-dev
       - xvfb
 
+before_install:
+  - "/sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1280x1024x24"
+#${DISPLAY}
+  - sleep 3
+
 install:
   - if [[ "${TRAVIS_OS_NAME}" = "osx" ]]; then brew update && brew install ninja qt5; fi
   - gem install bundler

travis.sh

@@ -30,23 +30,23 @@ cmake --build build --target features
 # Start virtual X display server
 
 # Starting Xvfb hangs on OSX, that's why we do this on Linux only now
-if [ "${TRAVIS_OS_NAME}" = "linux" ]; then
-    DISPLAY=:99
-    export DISPLAY
-
-    # Xvfb sends SIGUSR1 to its parent when it finished startup, this causes the 'wait' below to stop waiting
-    trap : USR1
-    (trap '' USR1; Xvfb $DISPLAY -screen 0 640x480x8 -nolisten tcp > /dev/null 2>&1) &
-    XVFBPID=$!
-    wait || :
-    trap '' USR1
-    if ! kill -0 $XVFBPID 2> /dev/null; then
-        echo "Xvfb failed to start" >&2
-        exit 1
-    fi
-else
-    unset DISPLAY
-fi
+#if [ "${TRAVIS_OS_NAME}" = "linux" ]; then
+#    DISPLAY=:99
+#    export DISPLAY
+#
+#    # Xvfb sends SIGUSR1 to its parent when it finished startup, this causes the 'wait' below to stop waiting
+#    trap : USR1
+#    (trap '' USR1; Xvfb $DISPLAY -screen 0 640x480x8 -nolisten tcp > /dev/null 2>&1) &
+#    XVFBPID=$!
+#    wait || :
+#    trap '' USR1
+#    if ! kill -0 $XVFBPID 2> /dev/null; then
+#        echo "Xvfb failed to start" >&2
+#        exit 1
+#    fi
+#else
+#    unset DISPLAY
+#fi
 
 for TEST in \
     build/examples/Calc/GTestCalculatorSteps \