Examining more realistic examples

The example we went through previously is very simple and a bit contrived. In a more realistic working environment, the dev branch will be very active: there will be many feature/bug fix branches that stem from dev and ultimately merge back into it. To illustrate how that can cause issues, and to show you how those issues can be mitigated, we're going back to the dev branch to create another feature branch; let's call it user-schema/main:

$ git checkout -b user-schema/main dev
Switched to a new branch 'user-schema/main'

Now, let's add a file, user-schema.js, which represents the entirety of our user schema feature:

$ touch user-schema.js
$ git add -A && git commit -m "Add User Schema"
[user-schema/main 8a31446] Add User Schema
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 user-schema.js

Now, we can merge this feature branch back into dev:

$ git checkout dev
Switched to branch 'dev'
$ git merge user-schema/main 
Updating cf3221a..8a31446
Fast-forward
 user-schema.js | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 user-schema.js

Our Git history tree now looks like this:

$ git log --graph --oneline --decorate --all
* 8a31446 (HEAD -> dev, user-schema/main) Add User Schema
| * 37eb1b9 (social-login/main) Resolve merge conflict
| |\ 
| | * 9204a6b (social-login/twitter) Implement Twitter login
| * | 09bc8ac (social-login/facebook) Implement Facebook login
| |/ 
| * 8d9f102 Add a blank social-login file
|/ 
* cf3221a (master) Add main script and documentation
* 85434b6 Update README.md
* 6883f4e Initial commit

If you're finding it hard to visualize the history, try using a Git client that visualizes the branches for you. For Mac and Windows, there's a free client by Atlassian called Sourcetree. If you're on Linux, you may want to try GitKraken. We will use GitKraken to illustrate the Git branch structure from here on. For example, the preceding figure looks like this on GitKraken: 

Now, we could merge our social-login/main branch back into dev, which will produce the following branch structure:

However, we should not do this because:

• Breaking changes: The implementation of the social login feature may depend on the user's schema being of a certain shape. Therefore, blindly merging the social-login/main branch may result in the platform breaking. The dev branch is the one that others will develop new features from, and so it should be kept bug-free at all times.
• Complicated Git history: The history tree is already quite hard to read, and we've only implemented two features!