python unittest assertIsInstance 意外结果

Question

我无法断言对象是 class 的实例在下面 class 你会看到 obj 确实是 TrieNode 的一个实例但是，单元测试失败，抱怨它是 Bool

from collections import defaultdict


class TrieNode:
    def __init__(self):
        self.children = defaultdict(TrieNode)
        self.is_word = False

    def suffixes(self, suffix = ''):
        """
        Recursive function that collects the suffix for
        all complete words below this point
        """
        pass


class Trie(object):
    def __init__(self):
        self.root = TrieNode()

    def add(self, word):
        """
        Add `word` to trie
        """
        current_node = self.root

        for char in word:
            current_node = current_node.children[char]

            current_node.is_word = True

    def exists(self, word):
        """
        Check if word exists in trie
        """
        current_node = self.root

        for char in word:
            if char not in current_node.children:
                return False

            current_node = current_node.children[char]

        return current_node.is_word

    def find(self, prefix):
        """
        Find the Trie node that represents this prefix
        :param prefix: For example 'f'
        :return: TrieNode 'f':{...}
        """
        current_node = self.root

        for char in prefix:
            if char not in current_node.children:
                return False

            current_node = current_node.children[char]

        return current_node


my_trie = Trie()
wordList = [
    "ant", "anthology", "antagonist", "antonym",
    "fun", "function", "factory",
    "trie", "trigger", "trigonometry", "tripod"
]
for word in wordList:
    my_trie.add(word)


obj = my_trie.find('a')
print(type(obj))                   # <class '__main__.TrieNode'>
print(isinstance(obj, TrieNode))   # True

如你所见，我得到了

  print(type(node_a))                   # <class '__main__.TrieNode'>
  print(isinstance(node_a, TrieNode))   # True

现在我有了这个单元测试

import unittest
from problem_05_trie_autocomplete import Trie, TrieNode


class TestTrieAutoComplete(unittest.TestCase):
    """
    python -m unittest
    """

    def setUp(self):
        self.my_trie = Trie()

    def test_add_to_trie(self):
        """
        Add words to Trie and check their existence
        :return:
        """

        word_list = [
            "ant", "anthology", "antagonist", "antonym",
            "fun", "function", "factory",
            "trie", "trigger", "trigonometry", "tripod"
        ]
        for word in word_list:
            self.my_trie.add(word)
            self.assertTrue(self.my_trie.exists(word))

    def test_assert_is_trienode(self):
        obj = self.my_trie.find('a')
        self.assertIsInstance(obj, TrieNode)

    def test_assert_is_with_type_trienode(self):
        obj1 = self.my_trie.find('a')
        self.assertIs(type(obj1), TrieNode)

我在最近两次测试中有两个错误


self.assertIsInstance(obj, TrieNode)
AssertionError: False is not an instance of <class 'problem_05_trie_autocomplete.TrieNode'>
======================
self.assertIs(type(obj1), TrieNode)
AssertionError: <class 'bool'> is not <class 'problem_05_trie_autocomplete.TrieNode'>

FAILED (failures=2)

为什么 obj 和 obj1 在 unittest 中是 Bool 同时在 class obj 是 TrieNode 的一个实例，它应该是？

提前致谢

Answer 1

谢谢@MisterMiyagi

这是为面临相同问题的人提供的解决方案要学习的一点是设置函数中 my_trie 的状态将是所有其他测试

将使用的状态

import unittest
from problem_05_trie_autocomplete import Trie, TrieNode


class TestTrie(unittest.TestCase):
    """
    python -m unittest
    """

    def setUp(self):
        self.my_trie = Trie()
        self.word_list = [
            "ant", "anthology", "antagonist", "antonym",
            "fun", "function", "factory",
            "trie", "trigger", "trigonometry", "tripod"
        ]
        for word in self.word_list:
            self.my_trie.add(word)

    def test_add_to_trie(self):
        """
        Add words to Trie and check their existence
        :return:
        """
 
        for word in self.word_list:
            self.my_trie.add(word)
            self.assertTrue(self.my_trie.exists(word))

    def test_unexisting_word(self):
        self.assertFalse(self.my_trie.exists("unexistingWord"))
        self.assertFalse(self.my_trie.find('x'))
        self.assertFalse(self.my_trie.find('y'))

    def test_assert_is_trienode(self):
        obj = self.my_trie.find('a')
        self.assertIsInstance(obj, TrieNode)

    def test_assert_is_with_type_trienode(self):
        obj1 = self.my_trie.find('a')
        self.assertIs(type(obj1), TrieNode)

python unittest assertIsInstance 意外结果

python unittest assertIsInstance unexpected result

python

unit-testing

python-3.x

python-unittest