anchor.diff:      (cd testing && ../build)
     '';
   
  -  installCheckPhase = "./run_tests";
  +  installCheckPhase = ''
  +    ./run_tests units
  +    ./run_tests binaries
  +
  +    # can also `./run_tests scripts`, but this fails due to lack of FSL package
  +    # (and there's no convenient way to disable individual tests)
  +  '';
     doInstallCheck = true;
   
     installPhase = ''
  
positive.code:   installCheckInputs = [ bc ];
  
    postPatch = ''
      patchShebangs ./build ./configure ./run_tests ./bin/population_template
      substituteInPlace ./run_tests  \
        --replace 'git submodule update --init >> $LOGFILE 2>&1' ""
    '';
  
    configurePhase = ''
  
negative.code: { stdenv, lib, fetchFromGitHub, python, makeWrapper
  , eigen, fftw, libtiff, libpng, zlib, ants, bc
  , qt5, libGL, libGLU, libX11, libXext
  , withGui ? true }:
  
  stdenv.mkDerivation rec {
    pname = "mrtrix";
    version = "3.0.0";
  
    src = fetchFromGitHub {
      owner  = "MRtrix3";
      repo   = "mrtrix3";
      rev    = version;
      sha256 = "1vvmmbw3m0bdfwp4szr62ygzsvkj0ss91cx5zlkspsr1rff05f9b";
      fetchSubmodules = true;
    };
  
  