如何在其他类中使用Python数据类

Question

我正在尝试掌握Python，但在尝试使用数据类时似乎遇到了瓶颈。但是当我运行测试时，我得到断言错误，因为它似乎没有看到正确的数据类。

我有以下代码:

文件:music_library.py

from dataclasses import dataclass
@dataclass
class Track:
title: str
artist: str
file: str
class MusicLibrary:
def __init__(self):
self.track = Track
def all(self):
return self.track
def add(self, title, artist, file):
self.track(title = title, artist = artist, file = file)

从测试中调用add函数，并传递三个参数:

import unittest
from player.music_library import MusicLibrary

class TestMusicLibrary(unittest.TestCase):
ml = MusicLibrary()
def test_all(self):
ml = MusicLibrary()
ml.add("Track1", "artist1","file1")
self.assertEqual(ml.all(), ["Track1","artist1","file1" ])

但是

测试失败

Traceback (most recent call last):
File "/projects/python/python-music-player-challenges/seed/tests/test_music_library.py", line 13, in test_all
self.assertEqual(ml.all(), ["Track1","artist1","file1" ])
AssertionError: <class 'player.music_library.Track'> != ['Track1', 'artist1', 'file1']

这是怎么回事?我显然漏掉了一些明显的东西。

感谢

Answer 1

像这样更新music_library.py:

from dataclasses import dataclass
@dataclass
class Track:
title: str
artist: str
file: str

class MusicLibrary:
def __init__(self):
self.track = None
def all(self):
return self.track
def add(self, title, artist, file):
self.track = Track(title=title, artist=artist, file=file)

注意上面代码中的数据类实例化。

并像这样更新您的测试用例:

import unittest
from music_library import MusicLibrary

class TestMusicLibrary(unittest.TestCase):
def test_all(self):
ml = MusicLibrary()
ml.add("Track1", "artist1", "file1")
self.assertEqual([ml.all().title, ml.all().artist, ml.all().file],
["Track1", "artist1", "file1"])

在您的测试代码中，您正在比较不同的对象类型，您应该首先将ml.all()的输出转换为list。

如果运行该测试，您将得到以下输出:

Ran 1 test in 0.000s
OK