selfassertEqual

Self.assertEqual is a method used in Python’s unittest framework to verify that two values are equal within a test case. It is invoked on an instance of a class derived from unittest.TestCase, typically inside a test method.

The method’s signature is assertEqual(first, second, msg=None). It compares first and second using the equality operator (==). If the two values are equal, the test passes and execution continues. If they are not equal, the method raises an AssertionError, and the unittest framework marks the test as failed. An optional message can be supplied via msg to provide additional context when the assertion fails.

Common usage involves checking the results produced by code under test against expected values. Example: in a test method, you might write self.assertEqual(sum([1, 2, 3]), 6). If the actual result differs from the expected value, the failure message includes the expected and actual values unless a custom message is provided.

Self.assertEqual is part of a family of related assertions, such as assertNotEqual, assertIs, and assertIsNot. For floating-point comparisons, there are specialized methods like assertAlmostEqual, which allows tolerance settings. When used thoughtfully, self.assertEqual helps ensure that functions and methods return precisely the intended values, contributing to robust and maintainable tests.