WIP: Enable tests

[inariksit]

Here are fixes by @kharus to get the test suite working again (issue #8). The problem with the old hardcoded paths is fixed, and the RGL path is read using DATA_DIR, which seems to be the current standard.

I tested on my computer and the path problem looks solved. However, I got stuck at this stage for 10 minutes, and my computer started freezing, so I stopped the process.

Building test suite 'gf-tests' for gf-3.10.4..
[1 of 1] Compiling Main
Linking .stack-work/dist/x86_64-osx/Cabal-2.4.0.1/build/gf-tests/gf-tests ...
7 modules in 1 directories.
Progress 0/2

• Is the problem due to compiling the RGL?
• Should we use the flag --no-pmcfg, like the setup script for the RGL does? Or would some important functionality be untested if we use that flag?
• Should we test the whole RGL with --no-pmcfg, and a subset of non-bloated RGL languages without the flag?

[kharus]

I realized that reading path to RGL will work only locally. rgl_lib_dir <- readFile "DATA_DIR" As RGL build copies data to DATA_DIR during it's own build process by relying on gf-rgl and gf-core checked out in the same directory.

But in github CI gf-rgl can't access gf-core DATA_DIR. So gf-rgl artifact needs to be stored (and probably versioned) separately and pulled during gf-core build process.

[johnjcamilleri]

I haven't looked at this closely, but you don't need to rely on DATA_DIR at all. You can install the RGL wherever you want with --dest=/path/to/rgl and then just set the GF_LIB_PATH environment variable accordingly or use the --gf-lib-path= flag when invoking GF.

[inariksit]

New pull request that removes the RGL tests in #114