Tool to test code existence

i am running an effort to see if any changes i make in an existing huge project, to any file / class / method exists ! So the idea is based on requirements we code everyday or until the coding phase of that project. During that course you write unit tests to ensure it works at unit level. Followed by end to end functional testing. This is to ensure your code works Now, i feel like testing if my code exists that i made changes for ! Since i believe if that code is present it should work as expected. I think of checking at this level is because the team is big here and everyday we have tons of developers working on same file/project, hence chances of overriding is high and in case of merging code there could be some misses.

If any tool already exists to check existence of files, project, and the lines of code (say method, or the lines of code) that takes what you want to check (user input), please share. And if not, can you give me pointers to help on how to check if method exists with the method code in - looking for an efficient way.