Pythonの単体テストとは何ですか? (詳細な例)

 >>> d = Dict(a=1, b=2)
>>> d['a']
1
>>> d.a
1

class Dict(dict):
    def __init__(self, **kw):
        super().__init__(**kw)
    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r"'Dict' object has no attribute '%s'" % key)
    def __setattr__(self, key, value):
        self[key] = value

import unittest

from mydict import Dict
class TestDict(unittest.TestCase):
    def test_init(self):
        d = Dict(a=1, b='test')
        self.assertEqual(d.a, 1)
        self.assertEqual(d.b, 'test')
        self.assertTrue(isinstance(d, dict))
    def test_key(self):
        d = Dict()
        d['key'] = 'value'
        self.assertEqual(d.key, 'value')
    def test_attr(self):
        d = Dict()
        d.key = 'value'
        self.assertTrue('key' in d)
        self.assertEqual(d['key'], 'value')
    def test_keyerror(self):
        d = Dict()
        with self.assertRaises(KeyError):
            value = d['empty']
    def test_attrerror(self):
        d = Dict()
        with self.assertRaises(AttributeError):
            value = d.empty

self.assertEqual(abs(-1), 1) # 断言函数返回的结果与1相等

with self.assertRaises(KeyError):
    value = d['empty']

with self.assertRaises(AttributeError):
    value = d.empty

if __name__ == '__main__':
    unittest.main()

$ python mydict_test.py

$ python -m unittest mydict_test
.....
----------------------------------------------------------------------
Ran 5 tests in 0.000s
OK