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Day 2 activities

Merge conflict practice

Depending on how you're interacting with this manual, you may be in a class. The instructor may have set up a repository for you to practice merge conflicts. If this is the case:

  • Every person has their own repository. Each person should fix the merge conflicts in their own repo. It will be called github.com/githubschool/conflict-practice-USERNAME, with username being your actual username.
  • We won't make you turn in your homework, but we will run a script to see if the activities are completed later. 😉

Work to resolve the merge conflicts in the conflicts repository

  1. Find your repository. It will be at github.com/githubschool/conflict-practice-USERNAME, where your username is replacing the word USERNAME.
  2. In your repository, navigate to the Pull Requests tab.
  3. There are three open pull requests, and all of them have merge conflicts to fix. We recommend fixing them in this order:
    • Update README
    • Minor CSS fixes
    • Updates to game manual
  4. View the pull request, and follow the steps to resolve the merge conflicts. When the merge conflict is resolved, merge the pull request.

Refresher: Fixing a merge conflict locally

We've learned a lot! Try resolving the conflicts yourself first. If you need extra assistance, use these instructions.

  1. Clone the repository to your local machine:

    git clone https://github.com/githubschool/conflict-practice-username.git

  2. Find and check out to the conflict branch using the git switch <branch> command. For example:

    git switch my-branch

  3. Merge main into the conflict branch: git merge main. The merge will be halted because a conflict exists.

  4. Read the response from Git. It will identify the file(s) with a conflict. Open the file(s) in your favorite text editor.

  5. Remove the conflict markers: <<<<<<<, =======, >>>>>>>

  6. Review the code, edit to keep the version you'd like.

  7. Stage the conflicting files you've now resolved, for example:

    git add conflict-file.txt

  8. Finish the merge commit that was halted in #3 with:

    git commit -m "merge main into my-branch"

  9. Push your conflict-free branch to GitHub:

    git push

Multiple conflict markers in "Minor CSS fixes"

In some cases, you may notice multiple conflict markers. When these appear, it is either because:

  1. You've got multiple conflicts in the same file, or
  2. Another developer has neglected to remove markers when fixing a previous conflict, and committed those markers to your project's history.

Regardless of the reason, it's up to you to resolve it as a steward of this project! Here's an example of how this might work from the pull request titled "Minor CSS fixes":

  1. Merge the main branch into your conflict branch. The multiple markers may look something like this.

    <<<<<<< HEAD
a {
<<<<<<< HEAD
    color: #000;
=======

/**a{
    color: #999999;
>>>>>>> main
}

a:hover{
    color: #fff;
=======
    color: #999999;
}

a:hover{
    color: #dddddd;
<<<<<<< HEAD
>>>>>>> main
=======
>>>>>>> main
}
**/

  2. Remove all conflict markers, regardless of where they originated.

    a {
    color: #000;

/**a{
    color: #999999;
}

a:hover{
    color: #fff;
    color: #999999;
}

a:hover{
    color: #dddddd;
}
**/

  3. Review the code so it will still build. In this example, the CSS needs a closing brace, and we'll also remove the commented code.

    a {
    color: #000;
}

The different types of merge conflicts in "Updates to game manual"

Not every conflict deals with content. For example, in the pull request "Updates to game manual", you can see content-type conflicts, but something new as well:

Auto-merging play/mini/mini_bored.html
CONFLICT (content): Merge conflict in play/mini/mini_bored.html
CONFLICT (modify/delete): play/manual/manual.html deleted in HEAD and modified in main. Version main of play/manual/manual.html left in tree.
Automatic merge failed; fix conflicts and then commit the result.

In this example, the file play/manual/manual.html has been deleted in our currently checked out branch (HEAD), and modified in main. You, as the developer in charge of resolving this conflict, must decide whether to remove the file (as has been decided on this branch), or to bring the file back with some modifications (as was started in main).

You'll find the file has automatically been put in your working directory (identified by the message from Git). If you choose to keep the file with modifications, just bring up the file in your favorite text editor, make the changes you'd like, stage the file with git add play/manual/manual.html and finish your merge commit.

To remove the file altogether, tell Git you'd like to remove the file with git rm play/manual/manual.html, and then finish your merge commit.