def get_input_dir(job_homedir=None):
    '''
    :param job_homedir: explicit value for home directory, used for testing purposes
    :rtype: string
    :returns: path to input directory

    Returns the input directory, where all inputs are downloaded
    '''
    if job_homedir is not None:
        home_dir = job_homedir
    else:
        home_dir = environ.get('HOME')
    idir = os.path.join(home_dir, 'in')
    return idir