Make Python unittest show AssertionError but no Traceback

Question

I have looked at the other related questions here but have not found my answer. I would like to simplify the output of my Python (2.7) unittests. Trying sys.tracebacklimit = 0 did not work.

Here is my code snippet (the real code generates lots of similar tests):

#!/usr/bin/python -E
import unittest
import os
import sys

class TestSequense(unittest.TestCase):
    pass

def test_dir_exists(dir):
    def test(self):
        self.assertTrue(os.path.isdir(dir),"ERROR: " + dir + " is not a directory")
    return test

if __name__ == '__main__':
    test = test_dir_exists("/something/not/set/correctly")
    setattr(TestSequense, "test_path",  test)
    #TODO trying remove unnecessary traceback info... still not working
    sys.tracebacklimit = 0
    unittest.main()

The output is currently:

F
======================================================================
FAIL: test_path (__main__.TestSequense)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "./simple_unittest.py", line 11, in test
    self.assertTrue(os.path.isdir(dir),"ERROR: " + dir + " is not a directory")
AssertionError: ERROR: /something/not/set/correctly is not a directory

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)

I would like it to look like this:

F
======================================================================
FAIL: test_path (__main__.TestSequense)
----------------------------------------------------------------------
AssertionError: ERROR: /something/not/set/correctly is not a directory

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)

Is this possible without parsing the output? The Traceback gives me no useful information and I am running 1000's of tests.

Thanks in advance!

Answer 1

unittest has a mechanism for hiding the contents of the TestCase.assert* methods in the traceback, as those really don't contain any useful information for failures. It looks for __unittest in the frame's globals. You can hide an entire module from the tracebacks by putting __unittest = True at the top of the module.

Answer 2

I'm not sure if it's possible with vanilla unittest module. But you should take a look at py.test, with it you can configure the amount of information shown in a traceback with the --tb switch.

Probably you are interested in

py.test --tb=line    # only one line per failure

See this page for a full list of options.

Answer 3

The trick is to catch the exception, strip out the bits that aren't needed and throw it again...

Based on this answer - the following code works...

#!/usr/bin/python -E
import unittest
import os
import sys

class TestSequense(unittest.TestCase):
    pass

def test_dir_exists(dir):
    def test(self):
       try:
           self.assertTrue(os.path.isdir(dir),"ERROR: " + dir + " is not a directory")
       except:
           # Remove traceback info as we don't need it
           unittest_exception = sys.exc_info()
           raise unittest_exception[0], unittest_exception[1], unittest_exception[2].tb_next
    return test

if __name__ == '__main__':
    test = test_dir_exists("/something/not/set/correctly")
    setattr(TestSequense, "test_path",  test)
    unittest.main()

And generates the following...

./simple_unittest.py
F
======================================================================
FAIL: test_path (__main__.TestSequense)
----------------------------------------------------------------------
AssertionError: ERROR: /something/not/set/correctly is not a directory

----------------------------------------------------------------------
Ran 1 test in 0.000s