Chapter 11: Testing Your Code

Testing a Function

unit test and test case

import unittest
from name_function import get_formatted_name
class NamesTestCase(unittest.TestCase):
    """Tests for 'name_function.py'"""
    def test_first_last_name(self):
        """Do names like 'Janis Joplin' work?"""
        formatted_name = get_formatted_name('janis', 'joplin')
        self.assertEqual(formatted_name, 'Janis Joplin')
    def test_first_middle_last_name(self):
        """Do names like 'Wolfgang Amadeus Mozart' work?"""
        formatted_name = get_formatted_name(
            'wolfgang', 'mozart', 'amadeus'
        )
        self.assertEqual(formatted_name, 'Wolfgang Amadeus Mozart')
if __name__ == '__main__':
    unittest.main()

• 使用单元测试编写测试用例可以用来自动测试，不用手动执行函数来测试
• 测试用例中每个以test_开头的函数都会自动执行
• 很多测试框架都会先导入测试文件再 运行。导入文件时，解释器将在导入的同时执行它。

• if 代码块检查特殊变量 name ，这个变量是在程序执行时设置的。

   如果这个文件作为主程序执行，变

  量name 将被设置为’main‘ 。在这里，调用unittest.main() 来运
  行测试用例。
  如果这个文件被测试框架导入，变量name 的值将不 是’main‘ ，因此不会调用unittest.main() 。

Testing a Class

常用的assert methods

有一个class如下

class AnonymousSurvey:
    """Collect anonymous answers to a survey question."""
    def __init__(self, question):
        """Store a question, and prepare to store responses."""
        self.question = question
        self.responses = []
    def show_question(self):
        """Show the survey question."""
        print(self.question)
    def store_response(self, new_response):
        """Store a single response to the survey."""
        self.responses.append(new_response)
    def show_results(self):
        """Show all the responses that have been given."""
        print("Survey results:")
        for response in self.responses:
            print(f"- {response}")

编写测试

import unittest
from survey import AnonymousSurvey
class TestAnonymousSurvey(unittest.TestCase):
    """Tests for the class AnonymousSurvey"""
    def test_store_single_response(self):
        """Test that a single response is stored"""
        question = "What language did you first learn to speak?"
        my_survey = AnonymousSurvey(question)
        my_survey.store_response('English')
        self.assertIn('English', my_survey.responses)
    def test_store_three_responses(self):
        """Test that three individual responses are stored properly."""
        question = "What language did you first learn to speak?"
        my_survey = AnonymousSurvey(question)
        responses = ['English', 'Spanish', 'Mandarin']
        for response in responses:
            my_survey.store_response(response)
        for response in responses:
            self.assertIn(response, my_survey.responses)
if __name__ == '__main__':
    unittest.main()

setUp()

• unittest.TestCase有一个setUp()方法，在setUp()内创建的对象，其他test_方法都能使用(必须加self.)
• Python在运行test_方法前会先运行setUp()方法(关键) ```python import unittest from survey import AnonymousSurvey

class TestAnonymousSurvey(unittest.TestCase): “””Tests for the class AnonymousSurvey”””

def setUp(self):
    """
    Create a survey and a set of responses for use in all test methods.
    """
    question = "What language did you first learn to speak?"
    self.my_survey = AnonymousSurvey(question)
    self.responses = ['English', 'Spanish', 'Mandarin']
def test_store_single_response(self):
    """Test that a single response is stored"""
    self.my_survey.store_response(self.responses[0])
    self.assertIn('English', self.my_survey.responses)
def test_store_three_responses(self):
    """Test that three individual responses are stored properly."""
    for response in self.responses:
        self.my_survey.store_response(response)
    for response in self.responses:
        self.assertIn(response, self.my_survey.responses)

if name == ‘main‘: unittest.main() ``` When a test case is running, Python prints one character for each unit test as it is completed. A passing test prints a dot, a test that results in an error prints an E, and a test that results in a failed assertion prints an F.