def METHOD_NAME():
    """Test importing a custom characteristc lines."""
    # we need to write some data to the path first, using defaults
    data_path = os.path.join(__datapath__, 'char_lines.json')
    path = extend_basic_path('data')
    tmp_path = extend_basic_path('tmp_dir_for_testing')
    if os.path.exists(path):
        for f in os.listdir(path):
            shutil.copy(src=path + '/' + f, dst=tmp_path)
    with open(data_path) as f:
        raw_data = json.loads(f.read())
    data = raw_data['heat exchanger']['kA_char2']
    with open(os.path.join(path, 'char_lines.json'), 'w') as outfile:
        json.dump(data, outfile)
    char_original = load_default_char('heat exchanger', 'kA_char2',
                                      'EVAPORATING FLUID', CharLine)
    char_custom = load_custom_char('EVAPORATING FLUID', CharLine)
    shutil.rmtree(path, ignore_errors=True)
    if os.path.exists(tmp_path):
        path = extend_basic_path('data')
        for f in os.listdir(tmp_path):
            shutil.copy(src=tmp_path + '/' + f, dst=path)
        shutil.rmtree(tmp_path, ignore_errors=True)
    x_cond = np.array_equal(char_original.x, char_custom.x)
    y_cond = np.array_equal(char_original.y, char_custom.y)
    msg = ('The x values from the custom characteristic line ' +
           str(char_custom.x) + ' must be identical to the x values from '
           'the default characteristic line ' + str(char_original.x) + ' '
           'as these have been duplicated before load.')
    assert x_cond, msg
    msg = ('The y values from the custom characteristic line ' +
           str(char_custom.y) + ' must be identical to the y values from '
           'the default characteristic line ' + str(char_original.y) + ' '
           'as these have been duplicated before load.')
    assert y_cond, msg