Unittests and Assert Raise

Using assert raise within tests is a tricky thing - So today I'll focus on how to properly use it :)

S0-E11/E30 :)

Unittest with self.assertRaise for function tests

Let's present example for function:

import unittest

def raiser_function():
    print "Is This function Called?"
    raise NotImplementedError()

class TestCase2(unittest.TestCase):
    def test_will_pass_self_assert_raise(self):
        # proper usage
        self.assertRaises(NotImplementedError, raiser_function)

    def test_with_self_assert_raise(self):
        # proper usage
        with self.assertRaises(NotImplementedError):
            raiser_function()

    def test_will_fail(self):
        # added intentionally this line below for the test not to fail.
        with self.assertRaises(NotImplementedError):
            # you should not call methoc/function inside of self.assertRaises, but give arguments and kwargs as self.assertRaises argument
            self.assertRaises(NotImplementedError, raiser_function())

if __name__ == "__main__":
    unittest.main()

Unittest with self.assertRaise for object method tests

Let's present example for object-method:

import unittest

class RaiserClass(object):
    def methodToRaiseNotImplementedError(self):
        print "Is This Test Called?"
        raise NotImplementedError()

class TestCase1(unittest.TestCase):
    def test_will_pass_self_assert_raise(self):
        self.assertRaises(NotImplementedError, RaiserClass().methodToRaiseNotImplementedError)

    def test_with_self_assert_raise(self):
        with self.assertRaises(NotImplementedError):
            RaiserClass().methodToRaiseNotImplementedError()

    def test_will_fail(self):
        # added intentionally this line below for the test not to fail.
        with self.assertRaises(NotImplementedError):
            raiser_object = RaiserClass()
            self.assertRaises(NotImplementedError, raiser_object.methodToRaiseNotImplementedError())

    def test_will_fail2(self):
        # added intentionally this line below for the test not to fail.
        with self.assertRaises(NotImplementedError):
            self.assertRaises(NotImplementedError, RaiserClass().methodToRaiseNotImplementedError())

if __name__ == "__main__":
    unittest.main()

Acknowledgements

Thanks!

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If you have any suggestions what I should blog about in the next articles - please give me a hint :)

See you tomorrow! Cheers!

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