g4tools comes with test programs of its own that may be usefull in case of problems (for example porting on a not yet covered platform).
You can build and run them with :
UNIX> <get g4tools.zip>
UNIX> <unzip g4tools.zip>
UNIX> cd g4tools/test/cpp
UNIX> ./build
UNIX> ./tools_test_histo
UNIX> ./tools_test_wroot
UNIX> etc...
(UNIX here is for Linux, macOS and Windows-10/cygwin).
Note that there is no need to have CLHEP and Geant4 installed to build and run the g4tools test programs. Good part of the code (in particular the histos and the code to write/read at the CERN-ROOT format) is on the STD/STL and common system functions. Anyway some dependencies toward "externals" starts to appear. The offscreen plotting part may use expat and freetype and the hdf5 code assumes that an HDF5 library is around. The access to these externals to build test programs are concentrated in the use_[expat,hdf5,...] shell scripts files.