{"id":3706,"date":"2022-07-06T04:37:14","date_gmt":"2022-07-06T04:37:14","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=3706"},"modified":"2022-07-09T07:33:29","modified_gmt":"2022-07-09T07:33:29","slug":"python-assertequal","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-unit-testing\/python-assertequal\/","title":{"rendered":"Python assertEqual"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use the Python assertEqual()<\/code> method to test if two values are equal.<\/p>\n\n\n\n

Introduction to the Python assertEqual() method #<\/a><\/h2>\n\n\n\n

The assertEqual()<\/code><\/code> is a method of the TestCase class of the unittest<\/a> module. The assertEqual()<\/code><\/code> tests if two values are equal:<\/p>\n\n\n

assertEqual(first, second, msg=None<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If the first<\/code> value does not equal the second<\/code> value, the test will fail. <\/p>\n\n\n\n
The msg<\/code> is optional. If the msg<\/code> is provided, it’ll be shown on the test result if the test fails.<\/p>\n\n\n\n
Python assertEqual() method example #<\/a><\/h2>\n\n\n\n
First, create a new module called main.py<\/code> and define the add()<\/code> function:<\/p>\n\n\n
def<\/span> add<\/span>(a, b)<\/span>:<\/span>\n    return<\/span> a + b<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, create a test module test_main.py<\/code> to test the add()<\/code> function:<\/p>\n\n\n
import<\/span> unittest\n\nfrom<\/span> main import<\/span> add\n\n\nclass<\/span> TestMain<\/span>(unittest.TestCase)<\/span>:<\/span>\n    def<\/span> test_add<\/span>(self)<\/span>:<\/span>\n        self.assertEqual(add(1<\/span>, 2<\/span>), 3<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, run the test:<\/p>\n\n\n
python -m unittest test_main.py -v<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
test_add (test_main.TestMain) ... ok\n\n----------------------------------------------------------------------\nRan 1<\/span> test in<\/span> 0.000<\/span>s\n\nOK<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Python assertNotEqual() method #<\/a><\/h2>\n\n\n\n
The assertNotEqual()<\/code> method tests if two values are not equal:<\/p>\n\n\n
assertNotEqual(first, second, msg=None<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If the first is equal to the second, the test will fail. Otherwise, it’ll pass. For example:<\/p>\n\n\n
import<\/span> unittest\n\nfrom<\/span> main import<\/span> add\n\n\nclass<\/span> TestMain<\/span>(unittest.TestCase)<\/span>:<\/span>\n    def<\/span> test_add<\/span>(self)<\/span>:<\/span>\n        self.assertEqual(add(1<\/span>, 2<\/span>), 3<\/span>)\n\n    def<\/span> test_add_floats<\/span>(self)<\/span>:<\/span>\n        self.assertNotEqual(add(0.2<\/span>, 0.1<\/span>), 0.3<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Run the test:<\/p>\n\n\n
python -m unittest test_main.py -v<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
test_add (test_main.TestMain) ... ok\r\ntest_add_floats (test_main.TestMain) ... ok\r\n\r\n----------------------------------------------------------------------\r\nRan 2<\/span> tests in<\/span> 0.001<\/span>s\r\n\r\nOK<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Since 0.2 + 0.1 returns 0.30000000000000004, it’s not equal to 0.3. Therefore, the following test passes:<\/p>\n\n\n
self.assertNotEqual(add(0.2<\/span>, 0.1<\/span>), 0.3<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • Use the assertEqual()<\/code> method to test if two values are equal. <\/li>
  • Use the assertNotEqual()<\/code> method to test if two values are not equal.<\/li><\/ul>\n
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