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Feature Branches

Created
Mar 30, 2022 6:31 PM
Department
Engineering
Category
Agile
Technology
Git
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Feature branch workflow

The idea behind using feature branches is that feature development takes place in a dedicated branch rather than disturbing the base branch. It also allows different contributors to the project to work on the same feature. The feature branch is only merged with the base branch after the PR is approved by peers. This also encourages collaborative workflow in the project.

Ideally it is encouraged to follow this branch structure:

develop -> Base branch for development

staging -> Staging environment

beta -> Beta environment (optional)

master -> Production environment

In this guide, develop is considered as the base branch.

How it works

The Feature branch workflow insists instead of committing directly to their local develop branch, developers create a new branch every time they start work on a new feature. Feature branches should have descriptive names, like animated-menu-items or issue-#1061. The idea is to give a clear, highly-focused purpose to each branch. Git makes no technical distinction between the develop branch and feature branches, so developers can edit, stage, and commit changes to a feature branch.

The following is a walk-through of the life cycle of a feature branch.

Start with the develop branch

All feature branches are created of the latest code state of a project.

git checkout develop

git fetch origin

git reset –hard origin/develop

This switches the repo to the develop branch, pulls the latest commits, and resets the repo’s local copy of develop to match the latest version.

Create a new-branch

Use a separate branch for each feature or issue you work on. After creating a branch, check it out locally so that any changes you make will be on that branch.

git checkout -b new-feature

This checks out a branch called new-feature based on develop, and the -b flag tells Git to create the branch if it doesn’t already exist.

Update, add, commit, and push changes

On this branch, edit, stage, and commit changes in the usual fashion, building up the feature with as many commits as necessary. Work on the feature and make commits like you would any time you use Git.

git status
git add <some-file>
git commit

Git rebase

Rebasing is the process of moving or combining a sequence of commits to a new base commit. Rebasing is most useful and easily visualized in the context of a feature branching workflow. The general process can be visualized as the following:

image

In the image above master is considered as the base branch

From a content perspective, rebasing is changing the base of your branch from one commit to another making it appear as if you’d created your branch from a different commit.

The primary reason for rebasing is to maintain a linear project history. For example, consider a situation where the master branch has progressed since you started working on a feature branch. You want to get the latest updates to the master branch in your feature branch, but you want to keep your branch’s history clean so it appears as if you’ve been working off the latest master branch.

A more real-world scenario to use git rebase would be:

  1. A bug is identified in the master branch. A feature that was working successfully is now broken.
  2. A developer examines the history of the master branch using git log because of the “clean history” the developer is quickly able to reason about the history of the project.

You have two options for integrating your feature into the master branch: merging directly or rebasing and then merging. The former option results in a 3-way merge and a merge commit, while the latter results in a fast-forward merge and a perfectly linear history.

Git rebase in standard mode will automatically take the commits in your current working branch and apply them to the head of the passed branch.

git rebase develop

This automatically rebases the current branch onto develop, which can be any kind of commit reference (for example an ID, a branch name, a tag, or a relative reference to HEAD).

Running git rebase with the -i flag begins an interactive rebasing session. Instead of blindly moving all of the commits to the new base, interactive rebasing gives you the opportunity to alter individual commits in the process. This lets you clean up history by removing, splitting, and altering an existing series of commits.

git rebase --interactive develop

This rebases the current branch onto develop but uses an interactive rebasing session. This opens an editor where you can enter commands (described below) for each commit to be rebased. These commands determine how individual commits will be transferred to the new base.

The rebasing edit commands are as follows:

pick 2231360 some old commit
pick f7f3f6d changed README
pick ee2adc2 Adds new feature
# Rebase 2cf755d..ee2adc2 onto 2cf755d
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
# d, drop = remove commit

Squash commits

If, instead of “pick”, you specify “squash”, Git applies both that change and the change directly before it and makes you merge the commit messages together. So, if you want to make a single commit from these three commits, you make the script look like this:

pick 2231360 some old commit
squash f7f3f6d changed README
squash ee2adc2 Adds new feature

When you save and exit the editor, Git applies all three changes and then puts you back into the editor to merge the three commit messages:

# This is a combination of 3 commits.
# The first commit's message is:
some old commit

# This is the 2nd commit message:
changed README

# This is the 3rd commit message:
Adds new feature

When you save that, you have a single commit that introduces the changes of all three previous commits.

Push feature branch to remote

Push the feature branch up to the central repository

git push -u origin new-feature

This command pushes a new feature to the central repository (origin), and the -u flag adds it as a remote-tracking branch. After setting up the tracking branch, git push can be invoked without any parameters to automatically push the new-feature branch to the central repository.

To get feedback on the new feature branch, create a pull request in Git.

Resolve feedback

Now teammates comment and approve the pushed commits. Resolve their comments locally, commit, and push the suggested changes to Git. Your updates appear in the pull request.

Merge your pull request

Before you merge, you may have to resolve merge conflicts if others have made changes to the repo. When your pull request is approved and conflict-free, you can add your code to the develop branch. Merge from the pull request in Github.