used get method for param to avoid key error,
added username, pathtoshare, ben variable for test
created mock function for _add_shares, _remove_share, _remove_beneficiary
created class for testing CheckShareablePathTest function
mock input for do_remove_beneficiary function
created test function for  do_add_share, do_remove_share, do_remove_beneficiary
added variable for testing
created test functions for _add_share, _remove_share, _remove_beneficiary