Git Development Practices

This document contains Think Company’s standards for using Git.

Table of contents

• Branches
• Commits
  • Messages
• Merging
• Pull Requests
• Misc.

This is a Git Style Guide inspired by How to Get Your Change Into the Linux Kernel, the git man pages and various practices popular among the community. Forked from: agis-/git-style-guide

If you feel like contributing, please do so! Fork the project and open a pull request.

Branches

• Identify branches by features (new development) or fixes (refactoring)
• Choose short and descriptive names

Bad Example (too vague):

$ git checkout -b feature/login_fix

Good Example:

$ git checkout -b feature/oauth-migration

• Identifiers from corresponding tickets in an external service (eg. a GitHub issue) are also good candidates for use in branch names. It’s even better if you include a short descriptive name that identifies what you’re working on. For example:

Good Example:

# GitHub issue #15
$ git checkout -b fix/issue-15

Better Example:

  # GitHub issue #15
  $ git checkout -b fix/issue-15-nav-dropdown

• Use dashes to separate words.

• When merging personal branches into shared branches, the personal branch should be rebased onto the shared branch first in order to maintain a clean history. If you need to clean up any commit messages or squash commits, use the -i flag to enter the rebase interactive mode. When you are done with the rebase, you will need to force push the new history to the remote.

  $ git checkout main && git pull
  $ git checkout feat/update-nav-color
  $ git rebase main
  # interactive rebase:
  $ git rebase -i main
  # force push the branch's new history to the remote
  $ git push --force

• ⚠️ You should NEVER use force push to rewrite history on a shared branch unless you really understand what you are doing! In the unlikely situation that it this is necessary, make sure the entire team is aware when it is happening, and what they need to do to safely update the branch without losing any of their work.

• Delete your branch from the upstream repository after it’s merged (unless there is a specific reason not to). To delete local and remote branches, use the following commands with caution:

  # delete a local branch
  $ git branch -d <branch_name>
  # delete an unmerged local branch
  $ git branch -D <branch_name>
  # delete a branch on the remote named "origin" (most common)
  $ git push -d origin <branch_name>

• 🤓 Use the following command while being on the main branch, to list merged branches:

  $ git branch --merged | grep -v "\*"

Commits

• Each commit should be a single logical change. Don’t make several logical changes in one commit. For example, if a patch fixes a bug and optimizes the performance of a feature, split it into two separate commits.

• Commit early and often. Small, self-contained commits are easier to understand and revert when something goes wrong.

• That being said, try not to split a single logical change into multiple commits that will not function independently. If further consolidation of commits is desired before merging into the main branch, use git rebase or git merge to squash commits.

• Commits should be ordered logically. For example, if commit X depends on changes done in commit Y, then commit Y should come before commit X.

• 🤓 rebase and —amend are useful commands that can help you maintain a clean commit history on your personal working branches. Learn them to save time and frustration!

Messages

• A commit message should be succinct and clearly describe the changes that are being made. Avoid non-informative, ambiguous wording such as “changes” or “fix”. Use additional lines in the commit message body to provide additional details, and any reference IDs for related work tickets.

  # good
  $ git commit -m "feat(header): add new brand logo"
  
  # bad
  $ git commit -m "Changes to the header"

• If a commit A depends on another commit B, the dependency should be stated in the message of commit A. Use the commit’s hash when referring to commits.

  Similarly, if commit A solves a bug introduced by commit B, it should be stated in the message of commit A.

• Consider having your team adopt a standard format for commit messages, such as Conventional Commits. Then, adding in tooling to help enforce the standard, such as commitlint and commitzen.

Merging

• ⚠️ Do not rewrite published history. The repository’s history is valuable in its own right and it is very important to be able to tell what actually happened. Altering published history is a common source of problems for anyone working on the project.

• However, there are cases where rewriting history is legitimate. These are when:

  • You are the only one working on the branch and it is not being reviewed.

  • You want to tidy up your branch (eg. squash commits) and/or rebase it onto the main branch in order to merge it later.

  That said, never rewrite the history of the main branch or any other special branches (ie. used by production or CI servers).

• Keep the history clean and simple. Just before you merge your branch:

  1. Make sure it conforms to the style guide and perform any needed actions if it doesn’t (squash/reorder commits, reword messages etc.)

  2. Rebase it onto the branch it’s going to be merged to:

     [my-branch] $ git fetch
     [my-branch] $ git rebase origin/main
     [my-branch] $ git push -f
     # then merge

     This results in a branch that can be applied directly to the end of the main branch and results in a very simple history.

     (Note: This strategy is better suited for projects with short-running branches. Otherwise it might be better to occassionally merge the main branch instead of rebasing onto it.)

• If your branch includes more than one commit, do not merge with a fast-forward:

Good Example (ensure that a merge commit is created):

$ git merge --no-ff my-branch

Bad Example:

$ git merge my-branch

Pull Requests

On most projects, you will typically use the source control platform (e.g. Github, Bitbucket, Azure DevOps) to merge branches through pull requests, rather than using the git merge command in a terminal. Pull requests should contain all the information necessary for another person to quickly understand, test, and review the code changes. We strongly encourage the use of pull request templates, so that your entire team can create consistent pull requests that include all of the necessary information. A good pull request will typically include the following:

• A summary of what the changes are and why they are being made
• Testing instructions
• Link(s) to any related stories or tickets
• Screenshots or screen recordings for UI/UX changes
• A checklist for the creator to ensure any required steps are taken (e.g. running tests)

🤓 Leverage CI/CD for your projects whenever possible in order to reduce the manual effort needed for pull request reviews (e.g. run linters and tests, deploy preview environments).

Misc.

• There are various workflows and each one has its strengths and weaknesses. Whether a workflow fits your case, depends on the team, the project and your development procedures.

  That said, it is important to actually choose a workflow and stick with it.

• Be consistent. This is related to the workflow but also expands to things like commit messages, branch names and tags. Having a consistent style throughout the repository makes it easy to understand what is going on by looking at the log, a commit message etc.

• Test before you push. Do not push half-done work. Use stashes to save it instead.

• Use annotated tags for marking releases or other important points in the history.

• Prefer lightweight tags for personal use, such as to bookmark commits for future reference.