Github/compare: How to diff two different files (different file names, both in HEAD)?

Question

Can I use the github /compare to display the difference between two different source files in HEAD?

Here is how I do it on the command line with git d

Answer 1

The Situation

On my DevOps team, it is very common to need to create new infrastructure resources (via Infrastructure As Code) which closely resembles existing infrastructure but with just a few changes. When a GitHub "Pull Request is received, the code reviewer is shown thousands of lines of code to Review and Approve. Even if they knew which small portion of the code should be changed, they should feel comfortable assuming "all that other green/new code must have be copied correctly from the correct spot.

I KNOW HOW TO DO THIS VIA THE CLI! But, because we have a workflow that centers around GitHub Enterprise (and private repos) my team doesn't use the CLI for this or much of anything.

The Stopgap Solution

Since GitHub only accepts points in history for comparisons and not paths I have to get clever.

Assuming FileA is the original and FileB is the modified file at a new path

• Create a temporary branch (using a naming convention like "diff-TICKET-1234")
• Copy FileA on top of FileB
• Commit it
• Push it out to github
• In the last commit message in the branch that is getting a PR (in this case "TICKET-1234"), add a comment:
  • See: https://github.com/org_name/repo_name/compare/diff-TICKET-1234..TICKET-1234