{"id":419,"date":"2024-01-29T11:04:10","date_gmt":"2024-01-29T11:04:10","guid":{"rendered":"https:\/\/learnpython.elegantwallp.com\/?p=419"},"modified":"2024-01-29T11:04:11","modified_gmt":"2024-01-29T11:04:11","slug":"python-assertis","status":"publish","type":"post","link":"https:\/\/learnpython.elegantwallp.com\/2024\/01\/29\/python-assertis\/","title":{"rendered":"Python assertIs()"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you\u2019ll learn how to use the Python assertIs()<\/code> to test if two objects are the same.<\/p>\n\n\n\n

Introduction to Python assertIs() method<\/h2>\n\n\n\n

The\u00a0assertIs()<\/code>\u00a0allows you to test if two objects are the same. The following shows the syntax of the\u00a0assertIs()<\/code>\u00a0method:<\/p>\n\n\n\n

assertIs(first, second, msg=None)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
If the first<\/code> and second<\/code> reference the same object, the test will pass. Otherwise, it\u2019ll fail.<\/p>\n\n\n\n
The msg<\/code> is optional. It\u2019s displayed in the test result in case the test fails.<\/p>\n\n\n\n
Technically, the assertIs()<\/code> method uses the is<\/code> operator:first is second<\/code><\/p>\n\n\n\n
Python assertIs() method example<\/h2>\n\n\n\n
First, create a\u00a0Logger<\/code>\u00a0singleton class in the\u00a0logger.py<\/code>\u00a0module:<\/p>\n\n\n\n
from datetime import datetime class Logger: _instance = None def __new__(cls): if cls._instance is None: cls._instance = super(Logger, cls).__new__(cls) return cls._instance def log(self, message): print(f'{datetime.now().strftime(\"%Y-%m-%d %H:%M:%S\")} {message}')<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The singleton is a design pattern that limits the instantiation of a class to a single instance. In other words, you\u2019ll have the same Logger<\/code> object regardless of how many times you call the Logger()<\/code> constructor.<\/p>\n\n\n\n
Second, create a\u00a0TestLogger<\/code>\u00a0class that tests the\u00a0Logger<\/code>\u00a0class:<\/p>\n\n\n\n
import unittest from logger import Logger class TestLogger(unittest.TestCase): def setUp(self): self.logger = Logger() def test_singleton(self): new_logger = Logger() self.assertIs(self.logger, new_logger)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
In the TestLogger<\/code> class:<\/p>\n\n\n\n
    \n
  • First, create a new instance of the Logger<\/code> class in the setUp()<\/code> method and assign it to the self.logger<\/code> instance variable.<\/li>\n\n\n\n
  • Second, create a new instance of the Logger class and use the assertIs()<\/code> method to check if two instances are the same.<\/li>\n<\/ul>\n\n\n\n
    If you run the test:<\/p>\n\n\n\n
    python -m unittest -v<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
    you\u2019ll get the following output:<\/p>\n\n\n\n
    test_singleton (test_logger.TestLogger) ... ok ---------------------------------------------------------------------- Ran 1 test in 0.000s OK<\/code>Code language: plaintext (plaintext)<\/small><\/code><\/pre>\n\n\n\n
    The test passed.<\/p>\n\n\n\n
    Python assertIsNot() method<\/h2>\n\n\n\n
    The\u00a0assertIsNot()<\/code>\u00a0tests if the first object is not the same as the second one:<\/p>\n\n\n\n
    assertIsNot(first, second, msg=None)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
    For example:<\/p>\n\n\n\n
    import unittest class TestInteger(unittest.TestCase): def test_integer_different_value(self): x = 10 y = 20 self.assertIsNot(x, y) def test_integer_same_value(self): x = 10 y = 10 self.assertIs(x, y)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
    Run the test:<\/p>\n\n\n\n
    python -m unittest -v<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
    Output:<\/p>\n\n\n\n
    test_integer_different_value (test_integer.TestInteger) ... ok test_integer_same_value (test_integer.TestInteger) ... ok ---------------------------------------------------------------------- Ran 2 tests in 0.001s OK<\/code>Code language: plaintext (plaintext)<\/small><\/code><\/pre>\n\n\n\n
    In this example, we use the assertIsNot()<\/code> method to test if two integer variables reference different objects. Since their values are different, they reference different objects.<\/p>\n\n\n\n
    In the second test case, we use the assertIs()<\/code> method to test if two integer variables reference the same object. Because their values are the same, they reference the same object.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Summary: in this tutorial, you\u2019ll learn how to use the Python assertIs() to test if two objects are the same. Introduction to Python assertIs() method The\u00a0assertIs()\u00a0allows you to test if two objects are the same. The following shows the syntax of the\u00a0assertIs()\u00a0method: If the first and second reference the same object, the test will pass. Otherwise, it\u2019ll fail. The msg is optional. It\u2019s […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[43],"tags":[],"class_list":["post-419","post","type-post","status-publish","format-standard","hentry","category-3-python-unit-testing"],"_links":{"self":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/419","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/comments?post=419"}],"version-history":[{"count":1,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/419\/revisions"}],"predecessor-version":[{"id":420,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/419\/revisions\/420"}],"wp:attachment":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/media?parent=419"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/categories?post=419"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/tags?post=419"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}