Add X11 emulation to travis so tests can run after build

Add guard against popping from empty stack

.travis.yml

@@ -58,6 +58,12 @@ install:
   - if [[ $TRAVIS_OS_NAME == 'osx' ]] ; then brew install qt5 ; fi
 #  - if [[ $TRAVIS_OS_NAME == 'osx' ]] ; then brew link --force qt5 && ln -s /usr/local/Cellar/qt5/5.9.1/mkspecs /usr/local/mkspecs && ln -s /usr/local/Cellar/qt5/5.9.1/plugins /usr/local/plugins ; fi
 
+#emulate x server to run the gui on linux - necessary for testing 
+before_script:
+  - if [[ $TRAVIS_OS_NAME == 'linux' ]] ; then export DISPLAY=:99.0 ; fi
+  - if [[ $TRAVIS_OS_NAME == 'linux' ]] ; then sh -e /etc/init.d/xvfb start ; fi
+  - if [[ $TRAVIS_OS_NAME == 'linux' ]] ; then sleep 3 ; fi # give xvfb some time to start
+
 script: 
   - if [[ $TRAVIS_OS_NAME == 'linux' ]] ; then cd bin && cmake -DCMAKE_C_COMPILER=gcc-5 -DCMAKE_CXX_COMPILER=g++-5 .. && make && ctest -V ; fi
   - if [[ $TRAVIS_OS_NAME == 'osx' ]] ; then cd bin && cmake .. && make && ctest -V ; fi

CMakeLists.txt

@@ -4,7 +4,7 @@ project(pfcrender)
 
 # The project version number.
 set(VERSION_MAJOR   0   CACHE STRING "Major version number.")
-set(VERSION_MINOR   4   CACHE STRING "Minor version number.")
+set(VERSION_MINOR   5   CACHE STRING "Minor version number.")
 set(VERSION_PATCH   0   CACHE STRING "Patch version number.")
 mark_as_advanced(VERSION_MAJOR VERSION_MINOR VERSION_PATCH)
 

src/ViewModel/ViewModelBuilder.cpp

@@ -147,7 +147,10 @@ ViewModelBuilder::_createGeometry(const QString& curve)
             stack.push(pos);
             continue;
         case ']': // pop position and direction from stack
-            pos = stack.pop();
+            if(stack.isEmpty())
+                qWarning("Tried to pop from empty stack. Ignoring this character");
+            else
+                pos = stack.pop();
             continue;
         case '_': // special command:  next color
             //            idx = colors.indexOf(pos.getColor())+1;