Merge Conflict Carnival

Overview

This year the Ada staff has generously agreed to contribute their culinary skills to a coding bootcamp booth offering food & info pamphlets at the Georgetown Carnival. It's the day before the festivities kick off and someone's Cavalier King Charles Spaniel has done his best to shred all of their recipes! Oh no! Can you help Ada staff put everything back together and save Carnival?

In this activity you'll be working with your fellow Adies to put together multiple scraps from a single recipe using Git. You'll accomplish this by successively merging in content from each individuals' copy of the recipes repo. Once all the of merges are finished (and any merge conflicts resolved) you'll have a complete recipe document which can be submitted to the original repository with a pull request.

Learning Goals

The goal of this activity is to give you exposure to the process of resolving merge conflicts. Because merge conflicts are a natural part of any collaborative development effort, this is an important skill to have as a developer.

With this activity you will be able to encounter and resolve merge conflicts in a controlled scenario where the correct resolution of all merge conflicts is clear.

Instructions

Baseline Setup

Before we can start putting the recipe together we need to make sure that everyone in your group is working from the same starting point and can effectively contribute to the recipe building effort.

1. Split into groups: Follow your classroom instructors directions.

   • Breakout Rooms 1,9: Aardvark
   • Breakout Room 2,10: Curassow
   • Breakout Room 3,11: Gecko
   • Breakout Room 4,12: Sloth
   • Breakout Room 5,13: Lionfish
   • Breakout Room 6,14: Pangolin
   • Breakout Room 7,15: Rhino
   • Breakout Room 8,16: Tarsier

2. Fork the activity repo: One person in your group should fork the carnival-recipes repo and then add everyone else as a collaborator.

   • To add collaborators, go to Settings --> Manage access --> Invite teams or people
   • Invite collaborators will need to accept the invitation.

3. Clone the forked repo: Everyone in your group should clone the forked repository.

   • Check that you have the proper remote (and not the AdaGold remote) by typing git remote -v in the terminal.

4. Find your recipe scrap: Each group is assigned six(6) or seven(7) recipe scraps that should all be part of the same recipe. You can split these scraps up amongst your group however you wish.

5. Find your recipe scrap: Each group is assigned six(6) or seven(7) recipe scraps, located in the /scraps directory, that should all be part of the same recipe. You can split these scraps up amongst your group however you wish.

6. Add your recipe scrap: Copy the contents of your recipe scrap into the recipe file and then add and commit your changes to the recipe file. After completing this step each person in your group should have different content within the recipe file in their local repository.

Do not push your changes to GitHub yet! If you're finished early with this step help your groupmates.

Building the recipe

Once everyone in your group has completed the baseline setup instructions above you're ready to start building the recipe together.

Because each member of your group now has a different version of the recipe file in their local repository, building the complete recipe by merging those versions together will result in merge conflicts. To handle those merge conflicts sensibly your group should use the following process to construct the final recipe file:

1. Each person on a team will create a branch with git checkout -b BRANCH-NAME, selecting their own branch name based off the recipe scrap they have, and commit the changes they have made to the recipe.
2. Each team member will push their changes up to github with git push origin BRANCH-NAME.
3. Each team member will open a pull request trying to merge their branch on github into master. Be very careful to make the PR against your forked repository and NOT AdaGold.
   • To make the PR against your team members forked respository and not AdaGold, we will need to change the base repository
   • If there is a report of a merge conflict you will need to:
     • Pull the current state of master into their feature branch with git pull origin master
     • in VS code select accept both changes
     • Resolve the merge conflicts by rearranging the recipe and commit the result
     • Push the result up to github with git push origin BRANCH-NAME
     • Then attempt to merge their pull request. If new changes have happened on master they may have to repeat step 1 above.
4. Merge changes simultaneously, kind of like the ad-hoc strategy.
   • Remember: Whoever on your team is merging their changes into master must successfully finish that process (including fixing any merge conflicts!) before the next person can begin. Help them with resolving the conflicts.
   • Work with your fellow team members to resolve any merge conflicts.
5. Once everyone's changes have been merged together, the group as a whole should review it for completeness.
   • Make sure that none of the lines from your individual scrap are missing from the final result.
   • If there are any fixes needed, pick one person in the group to make the necessary changes and commit them.
6. When everyone agrees that the recipe looks correct one person should submit a PR to the original carnival-recipes repo.
7. Finally, debrief with your whole group about how things went.
   • What went well? What didn't?
   • Were there any merge conflicts that were particularly tricky to figure out?
   • How could this process have been made easier?
   • Write up a set of steps to follow when dealing with merge conflicts.

Activity Workflow

General advice

There are a few things to look out for when working through this activity:

• The end result should be a real, usable recipe. The original recipe files were all complete works from various recipe websites online.
• If you find that the result of one of your merges is missing critical ingredients or any numbered steps, you should go back and double check that you didn't lose any lines while resolving a merge conflict.
• Your recipe scraps may have duplicate lines. We've added these in to more accurately portray the full range of potential merge conflicts. Important: you should get rid of any duplicate lines while merging.
• There's no "right" way to do this activity, all of the strategies listed below are valid ways to build the recipe file.
• Have fun!

Collaboration strategies

There are a number of ways that a group of developers can collaborate to handle merging their changes together into a final, correct result. Each strategy has pros and cons. For example if a particular strategy is good for minimizing the number of complex merge conflicts, it probably requires a slower development process in which developers are often waiting on their peers to merge in changes before they can start working.

There are several ways for teams to collaborate on a project and handle merging changes into a single master branch on Github.

• Round robin: This strategy involves direct coordination between everyone in the group, resulting in a strictly ordered merge sequence.
  • One at a time each person pushes their changes and resolves any merge conflicts.
  • The next person in turn pulls those changes and pushes their own until everyone's changes have been pushed.
• Ad-hoc: This approach relies the most upon Git's merge coordination capabilities to ensure that everyone's changes get merged in properly.
  • Essentially, everyone attempts to git push at once.
  • The first person to get there doesn't have to merge, but everyone after that probably will.
• Branched: This approach is kind of a mix of the other two.
  • It uses a more advanced feature of Git known as branching.
  • Branching is generally considered the heart of a Git-based workflow and you'll have an opportunity to try it on a larger team project. This is what we're trying today!

Resources

• Original Diagram Image
• Intro to Git
• Branches in Git.
• Git Cheat Sheet