Git Tutorial: Handling Merges and Pull Requests

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Prerequisites:

• Basic knowledge of Git commands.
• A GitHub account.

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Objective:

By the end of this tutorial, you should be able to:

1. Clone a repository.
2. Make changes and push them.
3. Raise a pull request (PR).
4. Resolve merge conflicts.

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Let's Get Started!

1. Fork the Repository:

Start by forking the existing repository. This repository is located on a remote server, which is typically GitHub for most projects. By forking it, you create a local copy which you can edit and push back to the remote repository.

When you fork the project, make sure to unselect the option to Copy the main branch only.

Next, clone the repo:

$ git clone https://github.com/[YOUR_GITHUB_ID]/Introduction_to_Git/

If you check the repo, you should see the two branches main and dev:

$ git branch -a

2. Create a New Branch:

Checkout the remote dev branch and then create a new branch from dev using the following command:

$ git checkout remotes/origin/dev
$ git checkout -b [your_name]-choice

Replace [your_name] with your actual name.

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3. Choose Your Greek God:

Open the provided text file greek_gods.tx in the repository. Choose one Greek god from the following list and replace the one in the file:

• Hera
• Poseidon
• Demeter
• Athena
• Apollo
• Artemis
• Ares
• Aphrodite
• Hephaestus
• Hermes
• Dionysus

Save and close the file.

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4. Commit and Push:

Commit your changes and push them to your branch on the remote GitHub repository.

$ git add .
$ git commit -m "Chose my Greek god"
$ git push origin [your_name]-choice

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5. Raise a Pull Request:

Now, return to the GitHub repository online:

1. Click on "Pull Requests".
2. Select "New Pull Request".
3. For the base repository, choose the original repository (not your fork) and its main branch. For the head repository, pick your fork and your branch ([your_name]-choice).
4. Review your changes and click "Create Pull Request".
5. Add a title and description for your PR and submit.

Given the pre-existing change in the original repository's dev branch, you should encounter conflicts during the PR. Proceed to the next steps to resolve them.

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6. Using git diff:

The git diff command allows you to view differences between your working directory and the index (staged changes). This is helpful to review changes before committing.

After you've made changes but before committing:

$ git diff

This will show you the changes in your working directory compared to the last commit.

If you've already staged the changes (i.e., after using git add):

$ git diff --staged

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7. Using git log --merge:

During a merge conflict:

$ git log --merge

This command will show you the history of the commits that are causing the conflict, helping you make a more informed decision on how to resolve it.

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8. Resolve Merge Conflicts:

Open the text file on GitHub by selecting the option to Resolve Conflicts, and on the web editor you'll see conflict markers:

<<<<<<< HEAD
Apollo
=======
Athena
>>>>>>> [commit_hash]

To resolve this:

1. Decide which choice to keep or combine them (in this case, keep your changes).
2. Remove the conflict markers (<<<<<<<, =======, >>>>>>>).
3. Save the file.

After resolving all conflicts, create the PR.

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9. Resolving Merge Conflicts with git mergetool:

When you encounter a merge conflict:

$ git mergetool

This will open a GUI that displays the conflict. Follow the tool's instructions to resolve the conflict and then save and exit.

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10. Merge the PR:

Finally, merge the PR.

Congratulations! You've now tackled changes, navigated conflicts, and initiated a PR. Handling merge conflicts can seem daunting at first, but with practice, it becomes intuitive. This exercise imparts the collaborative flow of team projects using Git and GitHub, enhancing your version control skills.