How to see intermediate fail results from unittest as tests are running?

Peter Otten __peter__ at
Thu Aug 19 09:41:02 CEST 2010

Margie Roginski wrote:

> I am using unittest in a fairly basic way, where I have a single file
> that simply defines a class that inherits from unittest.TestCase and
> then within that class I have a bunch of methods that start with
> "test".  Within that file, at the bottom I have:
> if __name__ == "__main__":
>     unittest.main()
> This works fine and it runs all of the testxx() methods in my file.
> As it runs it prints if the tests passed or failed, but if they fail,
> it does not print the details of the assert that made them fail.  It
> collects this info up and prints it all at the end.
> Ok - my question: Is there any way to get unittest to print the
> details of the assert that made a test fail, as the tests are
> running?  IE, after a test fails, I would like to see why, rather than
> waiting until all the tests are done.

Not exactly what you're asking for, but 2.7 has grown a --failfast option 
that tells unittest to stop on the first failure. For older Python versions
you can use nose

nosetests -x

or the unittest backport at


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