Permission denied error during test

[JackDunnNZ]

If the package is installed normally, the folder is read-only and this causes the tests to fail when it tries to save the model to a file in the test directory:

Example: Error During Test at /Users/jack/.julia/packages/XGBoost/fI0vs/test/runtests.jl:78
  Got exception outside of a @test
  LoadError: Call to XGBoost C function XGBoosterSaveModel failed: [09:55:26] /workspace/srcdir/xgboost/dmlc-core/src/io/local_filesys.cc:209: Check failed: allow_null:  LocalFileSystem::Open "xgb.model": Permission denied
  Stack trace:
    [bt] (0) 1   libxgboost.dylib                    0x000000011b1fe02e dmlc::LogMessageFatal::~LogMessageFatal() + 110
    [bt] (1) 2   libxgboost.dylib                    0x000000011b3cb414 dmlc::io::LocalFileSystem::Open(dmlc::io::URI const&, char const*, bool) + 1060
    [bt] (2) 3   libxgboost.dylib                    0x000000011b3ae09e dmlc::Stream::Create(char const*, char const*, bool) + 62
    [bt] (3) 4   libxgboost.dylib                    0x000000011b1f872a XGBoosterSaveModel + 122
    [bt] (4) 5   ???                                 0x000000011a8f2356 0x0 + 4740555606
    [bt] (5) 6   ???                                 0x000000011a8f25bb 0x0 + 4740556219
    [bt] (6) 7   libjulia.1.5.dylib                  0x000000010fc5b560 eval_body + 1360
    [bt] (7) 8   libjulia.1.5.dylib                  0x000000010fc5b83d jl_interpret_toplevel_thunk + 269
    [bt] (8) 9   libjulia.1.5.dylib                  0x000000010fc74e3f jl_toplevel_eval_flex + 3151


  Stacktrace:
   [1] error(::String, ::String, ::String, ::String) at ./error.jl:42
   [2] XGBoosterSaveModel(::Ptr{Nothing}, ::String) at /Users/jack/.julia/packages/XGBoost/fI0vs/src/xgboost_wrapper_h.jl:11
   [3] save(::Booster, ::String) at /Users/jack/.julia/packages/XGBoost/fI0vs/src/xgboost_lib.jl:109
   [4] top-level scope at /Users/jack/.julia/packages/XGBoost/fI0vs/test/example.jl:52
   [5] include(::String) at ./client.jl:457
   [6] top-level scope at /Users/jack/.julia/packages/XGBoost/fI0vs/test/runtests.jl:79
   [7] top-level scope at /Users/sabae/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Test/src/Test.jl:1115
   [8] top-level scope at /Users/jack/.julia/packages/XGBoost/fI0vs/test/runtests.jl:79
   [9] top-level scope at /Users/sabae/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Test/src/Test.jl:1115
   [10] top-level scope at /Users/jack/.julia/packages/XGBoost/fI0vs/test/runtests.jl:10
   [11] include(::String) at ./client.jl:457
   [12] top-level scope at none:6
   [13] eval(::Module, ::Any) at ./boot.jl:331
   [14] exec_options(::Base.JLOptions) at ./client.jl:272
   [15] _start() at ./client.jl:506
  in expression starting at /Users/jack/.julia/packages/XGBoost/fI0vs/test/example.jl:52