dmerejkowsky/kata-git

Git katas

Git Katas

Notes:

You should never use push --force or equivalent unless otherwise stated

You should try and perform all the tasks listed here using the command line first, and relying on a GUI later.

At any time, feel free to run:

git log --all --graph --oneline

To see all of the commits history.

Task 1 - Create a new empty repo and make a commit

$ cd
$ mkdir repos
$ cd repos
$ mkdir kata
$ cd kata
$ git init
$ # create a file named 'hello.txt' containing "Hello, world"
$ git add hello.txt
$ git commit -m "Initial commit"

It's possible git will ask you to configure your name and email before allowing you to commit - if so, do what it says by running git config with the correct arguments.

Then verify using git log that you did create a commit

Task 2 - Configure an editor

Learn how to configure the text editor used by git - popular choices include VSCode, Notepad, Notepad++, vim, nano, and so on.

Open hello.txt and change "Hello, world" to "Hi folks!".

Make sure the changed are saved

Use the command git status the assert the presence of the change

Finall, run:

$ git add hello.txt
$ git commit

This time, you should see the git command pause and your editor starting.

The commit will be done when you edit and close the file containing the commit message.

Create a long message spanning several lines:

Replace "hello world" with "hi folks"

Use more inclusive language

then use git log again to check everything worked as intended.

Task 3 - Clone this repo

You have to clone this to clone this repo in a place where you have write access.

You can either fork it on GitHub, re-create it from scratch on GitLab for instance, or import it.

If you use the command line, make sure to change the working directory after cloning the repo, for instance:

$ git clone https://github.com/dmerejkowsky/kata-git
# this wil create a `kata-git` repository
$ cd kata-git

Task 4 - git log, git blame

There's a typo in the file numbers.txt - find the name and email of the dev who is responsible for this !

Task 5 - Two commits from one file

Goal: learn about the git index

This should be done by each member of the team.

• Change at least two different lines in index.html file (I'm sure you can find something to improve)

• Make two commits, each one containing a different line change.

Task 6 - Undoing changes

Goal: learn about the various ways to undo changes in git

This should be done by each member of the team.

• Revert the two commits made during task 2

• Change a few lines in index.html and then restore the file to its original version

• Move the head of the branch to where it was before task 2 started branch

Task 7 - Start working on a new branch

Goal: learn about creating a new branch and switching to it

• Create a new branch called experimentations and switch to it
• Change something in the index.html file and make a commit
• Confirm that the change is only in the experimentations branch: switch back to the main branch and verify that the changes you just made are no longer there.

Task 8 - The cycle of collaboration

Goal: learn how to share a branch across the same team

Make sure Alice and Bob both have cloned the repo and that they both have switched to the main branch.

• Alice: add your name to the THANKS file
• Alice: make a commit with the message "Add Alice to THANKS file"
• Alice: push the commit to the main branch
• Bob: get Alice's changes from the main branch (using fetch and merge for instance)
• Bob: make a commit with the message "Add Bob to THANKS file"
• Bob: push the commit to the main branch
• Alice: update the main branch

Alice should end up with a log looking like this:

* 6430036 - Add Bob to THANKS file (62 seconds ago) <bob>
--- a/THANKS
+++ b/THANKS
@@ -1 +1,2 @@
 Alice
+Bob

* a6c829f - Add Alice to THANKS file (2 minutes ago) <alice>
-
+Alice

Task 9 - Happy merge

Goal: show how to merge in the trivial case

• Alice: Change the <title> in index.html
• Alice: push the changes to the main branch
• Bob: do not fetch Alice's changes
• Bob: change something in the JavaScript code inside the index.html file
• Bob: make a commit and try to push it to the main branch - git will ask your to merge first
• Bob: merge your branch and push the result

Task 10 - Happy rebase

Some as the previous one, but use rebase so that there is no merge commit in the history.

Task 11 - Conflict resolution

Goal: learn about merging conflicting changes

• Alice: Edit 'conflict.txt' and add the following text on line 2:

C'est la goutte d'eau qui met le feu aux poudres

• Alice: make a commit and push it to the main branch

• Bob: make sure to not fetch Alice's changes at this point.

• Bob: Edit 'conflict.txt' and add the following line also on line 2:

C'est l'étincelle qui fait déborder le vase

• Bob: make a commit and try to push it to the main branch - git will ask your to merge first

• Bob: try and merge - git will tell you that there are conflicts

• Alice & Bob: resolve the conflict and push the resolution

Task 12 - Code review using a feature branch

• Alice: switch to a new branch named feature/stuff
• Alice: Add some code in 'index.html'
• Alice: Make sure to include a small mistake in the code you added
• Alice: Make a commit and push the branch
• Alice: Create a merge request (GitLab) or a pull request (GitHub, Azure DevOps)
• Bob: look at Alice's changes and leave some comments about the typo
• Alice: Use rebase or git commit --amend to address Bob's feedback and fix the typo (you are allowed to use push --force this time)
• Bob: Merge Alice's branch

Task 13 - Interactive rebase

Switch to the dev branch.

Verify that there are 5 commits between main and dev (most recent last):

* Add transaction parser
* Refactor old code
* Compute transaction price
* Fix issue on parser
* Compute transaction price: add test

Use an interactive rebase of dev on top of main so that the history looks like this:

* Refactor old code
* Add transaction parser
* Compute transaction price

Hints:

• You can do it in several passes
• You can create a tag to verify your rebase does presevre all the changes

Task 14 - Cherry-pick and make a release

If you look at the repo, you will see that the 'release' branch does not contain the commit that bumps the year in the COPYRIGHT file (which is expected since it was created in 2021).

Use git diff to confirm this.

Then use cherry-picking to fix the COPYRIGHT year on the release branch as well

Finally, create an push a v1.1 tag on the release branch