Quite often, as a competitive programmer, I feel irritated when an easy problem yields WA because of a teeny-tiny bug like a typo or a missing initialisation. It often costs a lot of precious time and several penalties.
For this problem, I've designed a small, simple, easy-to-use GUI application in Java which takes two source codes and tests them against a common input. The respective outputs obtained are then compared line by line for a mismatch. One can compare the 'buggy' code with a brute force solution to obtain a test case in which the faulty solution fails.
Link : https://github.com/sarthakmanna/Bug-Finder
Pre-requisites : Java8 or later must be preinstalled.
Currently supported languages : C++, Java, Python2, Python3
Other details are provided in the 'README.md' file of the above git repo.
If you find any bug, please report it at firstname.lastname@example.org