anchor.diff:  
     preCheck = ''
       export HOME="$TMPDIR"
  -    cd tests
   
       # This test requires the nlp module, which we haven't
       # packaged yet. However, nlp is optional for transformers
       # itself
  -    rm test_trainer.py
  +    rm tests/test_trainer.py
     '';
  +
  +  # We have to run from the main directory for the tests. However,
  +  # letting pytest discover tests leads to errors.
  +  pytestFlagsArray = [ "tests" ];
   
     # Disable tests that require network access.
     disabledTests = [
  
positive.code: 
  buildPythonPackage rec {
    pname = "transformers";
    version = "3.1.0";
  
    src = fetchFromGitHub {
      owner = "huggingface";
      repo = pname;
      rev = "v${version}";
      sha256 = "0wg36qrcljmpsyhjaxpqw3s1r6276yg8cq0bjrf52l4zlc5k4xzk";
    };
  
    propagatedBuildInputs = [
  
negative.code:   ];
  
    checkInputs = [
      parameterized
      pytestCheckHook
      timeout-decorator
    ];
  