textwrap は覚えとこう

文字列を適当な長さで区切って diff を表示する - forest book のお題だけど、読み逃してる条件が無ければ textwrap で充分。

import textwrap

def limit_characters(line, start, width):
    return textwrap.wrap(line[start:], width)
    
def test_limit_characters_null():
    test_line = ""
    assert [] == limit_characters(test_line, 0, 2)

def test_limit_characters_max():
    test_line = "12345"
    result = {
        1: ["1", "2", "3", "4", "5"],
        2: ["12", "34", "5"],
        3: ["123", "45"],
        4: ["1234", "5"],
        5: ["12345"],
        6: ["12345"],
    }
    for i in xrange(1, 6):
        r = result[i]
        assert r == limit_characters(test_line, 0, i)

def main():
    test_limit_characters_null()
    test_limit_characters_max()

if __name__ == "__main__":
    main()