Naming sub-branches

There are multiple valid ways to name these sub-branches, but the most popular convention uses grouping tokens, with various delimiters. For example, our Facebook and Twitter login sub-branches can be grouped under the social-login grouping token, with a period (.) as a delimiter, and a sub-token such as facebook or twitter:

$ git checkout -b social-login.facebook social-login
Switched to a new branch 'social-login.facebook'
$ git branch
  dev
  master

  social-login
* social-login.facebook

You can use almost anything as a delimiter; the comma (,), hash (#), and greater-than sign (>) are all valid delimiters. However, there are several rules outlined under the git-check-ref-format part of the documentation that give valid reference names. For example, the following characters are unavailable: space, tilde (~), caret (^), colon (:), question mark (?), asterisk (*), and open bracket ([).

Most conventions I have encountered use a forward slash (/) as the delimiter, and so we do the same here. However, this poses a problem because branches are stored as text files under .git/refs/heads. If we create a sub-branch called social-login/facebook, then it'd need to be created at .git/refs/heads/social-login/facebook, but this is impossible in our case because the social-login name is already used for the file, and thus cannot act as a directory at the same time:

$ git checkout -b social-login/facebook social-login
fatal: cannot lock ref 'refs/heads/social-login/facebook': 'refs/heads/social-login' exists; cannot create 'refs/heads/social-login/facebook'

Therefore, when we create a new feature branch, we need to provide a default sub-token, such as main. With that in mind, let's delete our current feature branches and create them again with the main sub-token:

$ git checkout dev
$ git branch -D social-login social-login.facebook
$ git checkout -b social-login/main dev
$ git branch
 dev
 master
* social-login/main

We are now on the social-login/main feature branch, and can start developing our social login feature.

First, let's create that file and commit it to the social-login/main branch:

$ touch social-login.txt
$ git add -A && git commit -m "Add a blank social-login file"

Now, we are going to create a sub-feature branch and develop our Facebook login feature:

$ git checkout -b social-login/facebook social-login/main
$ echo "facebook" >> social-login.txt
$ git add -A && git commit -m "Implement Facebook login"

Now, do the same for the Twitter login feature, making sure to branch from the main feature branch:

$ git checkout -b social-login/twitter social-login/main
$ echo "twitter" >> social-login.txt
$ git add -A && git commit -m "Implement Twitter login"

We now have two sub-feature branches, one main feature branch, one dev branch, and our original master branch:

$ git branch
  dev
  master
  social-login/facebook
  social-login/main
* social-login/twitter