How to handle AssertionError in Python and find out which line or statement it occurred on?

Use the traceback module:

import sysimport tracebacktry:    assert True    assert 7 == 7    assert 1 == 2    # many more statements like thisexcept AssertionError:    _, _, tb = sys.exc_info()    traceback.print_tb(tb) # Fixed format    tb_info = traceback.extract_tb(tb)    filename, line, func, text = tb_info[-1]    print('An error occurred on line {} in statement {}'.format(line, text))    exit(1)

The traceback module and sys.exc_info are overkill for tracking down the source of an exception. That's all in the default traceback. So instead of calling exit(1) just re-raise:

try:    assert "birthday cake" == "ice cream cake", "Should've asked for pie"except AssertionError:    print 'Houston, we have a problem.'    raise

Which gives the following output that includes the offending statement and line number:

Houston, we have a problem.Traceback (most recent call last):  File "/tmp/poop.py", line 2, in <module>    assert "birthday cake" == "ice cream cake", "Should've asked for pie"AssertionError: Should've asked for pie

Similarly the logging module makes it easy to log a traceback for any exception (including those which are caught and never re-raised):

import loggingtry:    assert False == True except AssertionError:    logging.error("Nothing is real but I can't quit...", exc_info=True)