Summary: in this tutorial, you’ll learn the overview of the Python unittest assert methods to perform unit testing.
Introduction to Python unittest assert methods #
The TestCase class of the unittest module provides you with a large number of assert methods to test. The following table shows the most commonly used assert methods:
| Method | Checks that |
|---|---|
assertEqual(x, y, msg=None) | x == y |
assertNotEqual(x,y,msg=None) | x != y |
assertTrue(x, msg=None) | bool(x) is True |
assertFalse(x, msg=None) | bool(x) is False |
assertIs(x, y , msg=None) | x is y |
assertIsNot(x, y, msg=None) | x is not y |
assertIsNone(x, msg=None) | x is None |
assertIsNotNone(x , msg=None) | x is not None |
assertIn(x, y, msg=None) | x in y |
assertNotIn(x, y, msg=None) | x not in y |
assertIsInstance(x, y, msg=None) | isinstance(x, y) |
assertNotIsInstance(x, y, msg=None) | not isinstance(x, y) |
All of these methods have an optional msg parameter whose type is a string. The msg will be displayed in the test result if the test fails.
The following assert methods check the exceptions, warnings, and log messages:
| Method | Checks that |
|---|---|
assertRaises(exc, fun, *args, **kwds) | fun(*args, **kwds) raises exc |
assertRaisesRegex(exc, r, fun, *args, **kwds) | fun(*args, **kwds) raises exc and the message matches regex r |
assertWarns(warn, fun, *args, **kwds) | fun(*args, **kwds) raises warn |
assertWarnsRegex(warn, r, fun, *args, **kwds) | fun(*args, **kwds) raises warn and the message matches regex r |
assertLogs(logger, level) | The with block logs on logger with a minimum level |
assertNoLogs(logger, level) | The with block does not log on logger with a minimum level |
The following table shows the assert methods that perform more specific checks:
| Method | Checks that |
|---|---|
assertAlmostEqual(x, y) | round(x-y, 7) == 0 |
assertNotAlmostEqual(x, y) | round(x-y, 7) != 0 |
assertGreater(x, y) | x > y |
assertGreaterEqual(x, y) | x >= y |
assertLess(x, y) | x < y |
assertLessEqual(x, y) | x <= y |
assertRegex(s, r) | r.search(s) |
assertNotRegex(s, r) | not r.search(s) |
assertCountEqual(x, y) | x and y have the same number of elements in the same number. |
In the next tutorials, you’ll learn about the unittest assert methods in more detail and how to use them effectively.
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