How to fail a python unittest if the setUpClass throws exception

Question

I am having little trouble using the python setUpClass.

For example consider the following case

class MyTest(unittest.case.TestCase):

    @classmethod
    def setUpClass(cls):
        print "Test setup"
        try:
            1/0
        except:
            raise

    @classmethod
    def tearDownClass(cls):
        print "Test teardown"

A couple of questions

Is the above code the right way to handle test setUpClass exceptions (by raising it so that the python unittest can take care of it), there are fail(), skip() methods, but those can only be used by test instances and not the test classes.
When there is a setUpClass exception, how can we ensure that tearDownClass runs (unittest doesn't run it, should we manualy call it).

except: raise does nothing. (Except maybe mess up the stack trace, not sure.) You might as well leave the whole try..except block out. — millimoose
– millimoose, Commented Aug 15, 2012 at 20:47
for your second question: if you think you might raise an exception, then you should use a try..except (like the one you have) to call tearDownClass on an exception. After that, you could reraise the exception. — Jeff Tratner
– Jeff Tratner, Commented Aug 15, 2012 at 20:49
Thanks for the responses, as mentioned by Jeff, the second approach of calling tearDownClass and raising the exception is the solution. — sysuser
– sysuser, Commented Aug 15, 2012 at 21:01
@millimoose, It doesn't mess up the stack trace. That's the point of bare raise. — Mike Graham
– Mike Graham, Commented Aug 15, 2012 at 21:11

Y__ · Accepted Answer · 2012-08-25 13:16:09Z

You can call tearDownClass on an exception as Jeff points it out, but you may also implements the __del__(cls) method :

import unittest

class MyTest(unittest.case.TestCase):

    @classmethod
    def setUpClass(cls):
        print "Test setup"
        try:
            1/0
        except:
            raise

    @classmethod
    def __del__(cls):
        print "Test teardown"

    def test_hello(cls):
        print "Hello"

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

Will have the following output :

Test setup
E
======================================================================
ERROR: setUpClass (__main__.MyTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "my_test.py", line 8, in setUpClass
    1/0
ZeroDivisionError: integer division or modulo by zero

----------------------------------------------------------------------
Ran 0 tests in 0.000s

FAILED (errors=1)
Test teardown

Note : you should be aware that the __del__ method will be called at the end of the program execution, which is maybe not what you want if you have a more than one test class.

Hope it helps

Andriy Ivaneyko · Accepted Answer · 2018-08-09 13:30:10Z

1

The best option would be is to add handler for the except which calls tearDownClass and re-raise exception.

@classmethod
def setUpClass(cls):
    try:
        super(MyTest, cls).setUpClass()
        # setup routine...
    except Exception:  # pylint: disable = W0703
        super(MyTest, cls).tearDownClass()
        raise

answered Aug 9, 2018 at 13:30

Andriy Ivaneyko

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Comments

Bruno Rocha - rochacbruno · Accepted Answer · 2019-03-07 22:02:57Z

0

import contextlib

class MyTestCase(unitest.TestCase):

    @classmethod
    def setUpClass(cls):
        with contextlib.ExitStack() as stack:
            # ensure teardown is called if error occurs
            stack.callback(cls.tearDownClass)

            # Do the things here!

            # remove callback at the end if no error found
            stack.pop_all()

answered Mar 7, 2019 at 22:02

Bruno Rocha - rochacbruno

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Comments

saz01 · Accepted Answer · 2020-02-14 09:24:49Z

0

use tearDownModule. It should be called after setUpClass runs.

answered Feb 14, 2020 at 9:24

saz01

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