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Developing on Branches

We use branching to work on issues without modifying the main line. This ensures that the main line only contains functional code and handles merge conflicts that arise when multiple people are developing at the same time. For a quick rundown on branching in git, consult the official git documentation.

Creating a branch

When starting a new issue, you will want to create a new branch for it:

Caution

When creating branches locally, it uses your local copy to create the new branch. Remember to do a git pull if you intend on using the latest changes from the remote branch you are creating from.

Creating a new branch from main
# Switch to main
git switch main

# Update your local copy
git pull

# Clone a new branch from main
git switch -c <branch_name>

IMPORTANT: When creating a new branch for an issue, you must create the branch from main.

Branch naming convention

When working on a new issue, you will want to create a branch to work on it. We have the following branch naming convention:

user/<github_username>/<issue_number>-<issue_description>

Example

If Jill (GitHub Username: jill99) is going to take on an issue titled "Fix bug on pathfinding software" and the issue number is 39, then the branch named can be named something like user/jill99/39-fix-pathfinding-bug.

If the branch that you are creating is not tied to an issue, then you do not need to put an issue number. A descriptive title will suffice.

Tracking and committing changes

All files where new changes have been made must first be "staged" in order to make commits:

git add <FILES>

Files that are staged will be part of your next commit. Once you are confident in your changes and you are ready to finalize them, then you should commit your changes:

git commit -m "<commit_message>"

Be sure to add a commit message that is descriptive of the changes that you made. It is encouraged that you make commits often so you can keep track of your changes more easily and avoid overwhelmingly large commits when you look back on your version history.

When you are ready to move your local changes to a remote branch, you want to push to the correct branch and potentially set the upstream if it does not yet exist:

git push -u origin <current_branch_name>

Merging branches

There may be times where you want to merge two branches together, whether you diverged on some ideas and finally want to synthesize them, or you just want to update your issue's branch with the main branch. In any case, merging branches will be inevitable as part of the development process, so it is essential to understand how to merge branches.

# Checkout to destination branch
git checkout <dest_branch>

# Merge with local copy of other branch
git merge <other_branch>

# Checkout to destination branch
git checkout <dest_branch>

# Fetch from remote
git fetch

# Merge remote copy of other branch
git merge origin/<other_branch>

Info

Merging a remote branch into its local counterpart using the method above is essentially the same operation as git pull.

Once the merge operation is complete, your destination branch should have updates both from itself and the other branch that you merge. If you do a git log, you will also see a new commit that indicates that the merge happened.

Resolving merge conflicts

Merging two branches is not always easy since the commit history for both branches could look quite different, and therefore conflicting changes can easily be made. If you run into a scenario like this, you may get something like this:

image

Upon inspecting bar.txt, we see the following:

image

Resolving merge conflicts is not always a trivial task, but there are many ways to resolve them which include:

Tip

If you cannot resolve a merge conflict on your own, reach out to your lead for help!