A sample exception hook, that prints useful information if an AssertionError occures

assertion_hook.py

#!/usr/bin/env python3

import sys, pprint
import os.path

# save old exception hook
sys._old_excepthook = sys.excepthook

def assert_hook(exc_type, exception, traceback):
	if exc_type.__name__ == "AssertionError":
		# get info from traceback
		frame = traceback.tb_frame
		local = frame.f_locals
		line = frame.f_lineno
		codefile = frame.f_code.co_filename
		
		print("Assertion error in file '{}' at line {}:\n".format(codefile, line))
		
		with open(codefile) as f:
			# get statement at the line from the stacktrace and print it
			statement = f.readlines()[line-1]
			print(statement)
			
			# compile the statement in that line, get all variables from the compiled
			# code, put the variables from that line in a dict with the values from the
			# traceback and dump everything
			code = compile(statement.strip(), codefile, "single")
			names_at_line = filter(lambda name: name != "AssertionError", code.co_names)
			names_and_vars = dict( (name, local[name]) for name in names_at_line )
			
			print("Variables at this point:")
			pprint.pprint(names_and_vars)
	else:
		# all non AssertionError exception get handled
		sys._old_excepthook(exc_type, exception, traceback)

sys.excepthook = assert_hook

if __name__ == "__main__":
	i = 5
	for j in range(10):
		assert(j < i)
		print(j)