Pull requests

When collaborating with others on a project it is often useful to have a way to present code for review before it enters the codebase so that any changes decisions can be discussed and issues can be mitigated. Many projects use pull requests for this.

Pull requests can take many forms, but we will be focusing on the way GitHub implements them. Generally other git hosting platforms implement them similarly.

To do

If you aren’t familiar with Git have a look at the Git tutorial

You’ll want to pair up so that you can practice the workflow.

Discuss

Consider why you might create a branch as opposed to committing to master, what are the pros and cons? How do you decide what belongs in a particular branch?

Exercises

1. In your own repository

Creating and using pull requests within your own repository is easier than doing it for repositories belonging to others. We’ll use this to get to grips with the basic workflow.

1.1 Create a repository

Create a new GitHub repository, clone it and push an initial commit to master.

1.2 Make changes

Checkout a new branch, make some changes and push them to your new branch.

1.3 Create your pull request

Go to your repository on GitHub, you will see a notification asking you if you want to create a new branch.
Alternatively you can simply click the link that appears in the terminal when you push your new branch.
Fill out some details about the changes you’ve made and create your pull request.

1.4 Merge into master

There will be a merge button at the bottom of the page. You can also use git pull origin <branchname> from the command line to merge the branch into master, hence the term ‘pull request’.

2. Collaborating

2.1 Add your partner to your repository

Go to your repository’s page in GitHub and click on ‘Settings’ then ‘Manage access’. From here you should be able to invite your partner.

2.2 Create a pull request

Have your partner clone the repository make a branch, push some changes and create a pull request.

2.3 Review

Go to their pull request, go to the ‘Files changed’ tab and review their changes. You can make comments on each line by clicking the + icon that appears as you hover.

2.4 Approve and merge

Once you’re happy with their changes you can click ‘Review changes’ and ‘Approve’. You can also ‘Request changes’ if you so desire. Once approved you can merge their changes into master.

3 Experiment

You can try:

Having your partner fork from your repository and merging their changes in
Different access rules
Doing a pull request and review with git only