Python assertIn() (original) (raw)

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Summary: in this tutorial, you’ll learn how to use the Python assertIn() method to test if a member is in a container.

Introduction to the Python assertIn() method #

The assertIn() is a method of the TestCase class of the unittest module. The assertIn() method tests if a member is in a container:

assertIn(member, container, msg=None)Code language: Python (python)

If the member is in the container, the test will pass. Otherwise, it’ll fail. The msg is optional. It’ll be displayed in the test result when the test fails.

Internally, the assertIn() method uses the in operator to check:

member in containerCode language: Python (python)

Python assertIn() method examples #

The following example uses the assertIn() method to test if a number is in a list and a string is in another string:

`import unittest

class TestIn(unittest.TestCase): def test_in_list(self): self.assertIn(1, [1, 2, 3])

def test_in_string(self):
    self.assertIn('python', 'python tutorial')`Code language: Python (python)

Run the test:

python -m unittest -vCode language: Python (python)

Output:

`test_in_list (test_in.TestIn) ... ok test_in_string (test_in.TestIn) ... ok

Ran 2 tests in 0.001s

OK`Code language: Python (python)

Python assertNotIn() method #

The `assertNotIn()` method is the opposite of the assertIn() method. The `assertNotIn()` method tests if a member is not in a container:

assertNotIn(member, container, msg=None)Code language: Python (python)

For example:

`import unittest

class TestNotIn(unittest.TestCase): def test_not_in_list(self): self.assertNotIn(0, [1, 2, 3])

def test_not_in_string(self):
    self.assertNotIn('java', 'python tutorial')`Code language: Python (python)

Run the test:

python -m unittest -vCode language: Python (python)

Output:

`test_not_in_list (test_not_in.TestNotIn) ... ok test_not_in_string (test_not_in.TestNotIn) ... ok

Ran 2 tests in 0.000s

OK`Code language: Python (python)

Summary #

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