function getTestFilePaths(files){
  const target = globby.sync([files])

  // Hardhat supports js & ts
  const testregex = /.*\.(js|ts)$/;
  return target.filter(f => f.match(testregex) != null);
}
Returns a list of test files to pass to mocha.
@param  {String}   files   file or glob
@return {String[]}         list of files to pass to mocha