Matthew Ström

Case Study: Github Pull Request

For a developer working with git and GitHub, pull requests are big moments. Each one represents the culmination of a developer’s work, the moment where code goes from being ‘mine’ to ‘ours’. If it’s a developer’s first pull request to an open-source project, it can feel scary. If it’s a long-time contributor’s 12th pull request of the day, it can feel tedious. No matter what, pressing the green “Create Pull Request” button feels momentous.

Defining success

As one of the critical moments in the GitHub workflow, it’s important to identify what a successful pull request is. In my experience as a developer, two qualities mark a successful pull request:

  1. Confidence
    When drafting a pull request, my first thought is, “Did I do everything right?” There’s a mental checklist I run through: Am I merging from the right branch? Am I merging to the right branch? Did I get the right commits? Will I mess up anyone else’s work by making this merge? Successful pull requests are ones where I’m confident I’ve answered all these questions, and haven’t forgotten anything.
  2. Speed
    When submitting a pull request against a bug, or making a small change, I want to fly through the process as quickly as possible. I know firsthand how far developers will go to maximize their efficiency (I still struggle with exiting VIM), so I imagine that many users value speed even more than I do.

These qualities are tied together: confidence breeds speed, and faster pull requests lead to more productive and more confident users.

Measuring success

Improving the pull request process involves measuring confidence and speed; first, to understand the baseline of these metrics, and later, to see how changes impact use. Fortunately, there are a few questions we can ask to determine how confident users are when making pull requests, and how quickly they are able to submit them.

  1. Confidence
    • What percentage of Pull Requests are abandoned after partial completion?
    • What percentage of Pull Requests are deleted by their submitter immediately after creation?
  2. Speed
    • What is the median time for a user to submit a pull request?
    • How do these times break down according to input method (keyboard vs. mouse)?

These metrics don’t give us a complete understanding of confidence and speed, but provide a solid baseline for our work on the process.

Suggestions for improvement


After initiating a pull request, a user sees the following:

The pull request creation screen
The pull request creation screen

As an experienced user of GitHub, I know that the green check mark (“✓ Able to merge”) is not a guarantee that everything is OK. In fact, one of the biggest indicators of a mistake — “Commits” and “Files Changed” — is currently at the bottom of the user’s screen. In my example, though I have a nice green check mark, one look at the files changed tells me that something is wrong.

I definitely messed something up here
I definitely messed something up here

The following wireframe comprises three suggestion for increasing the confidence of a user making a Pull Request (with the existing layout for comparison):

Suggested improvements
Suggested improvements
  1. More “Am I good?”
    Putting more information about the impact of the Pull Request — file changes, additions and deletions — at the top of the visual hierarchy increases the likelihood of the Pull Requester spotting problems. Likewise, if everything is ok, seeing details that match the user’s expectations is reassuring.
  2. Less framing
    Reducing the relative importance of the page’s header (“Open a Pull Request”) gives us more space for moment-critical information
  3. Clearer wording
    “Able to merge” is vague. I suggest using the wording that exists on the Pull Request after it’s submitted: “✓ This branch has no conflicts with the base branch.”


Currently, navigating the page using the “tab” key involves 7 keypresses to focus the “Create Pull Request” button. This is only because the Pull Request’s name input is focused on page load; if a user’s device focuses the page differently (as some screen readers do), many more inputs are required to submit a pull request.

To make it much faster for users to submit a pull request, I recommend adding a keyboard shortcut for “Create Pull Request.”

Keyboard shortcuts increase speed
Keyboard shortcuts increase speed

Additionally, users who interact primarily via mouse are currently moving around 450 pixels between starting a pull request and submitting the pull request. Aligning the buttons that begin the pull request process with the button that submits a pull request would increase efficiency even further.

Button distance between initiating and completing a pull request
Button distance between initiating and completing a pull request


By identifying the key qualities of a successful pull request, finding quantitative metrics by which to measure improvement, and implementing small but meaningful changes to a few elements in the workflow, I believe a critical piece of the GitHub workflow can become even more efficient and error-free.

In the future, it would be interesting to explore more automation in the pull request process. The presence of third-party integrations (continuous integration, linting, etc) in the code review process has significantly improved code quality in my own use, and I have a feeling that the same would apply to the pull request workflow.

Quick note: This case study was prepared in early 2017 for GitHub as part of the job interview process. I didn’t get the job :)