In Github, an unit of work is pull request. When you start work on a bug or a feature, you create a new git branch and several commits in a branch. When you're happy with the work, you merge the branch to the master branch.
In Gerrit, an unit of work is a commit. Similar to Github, you create a new git branch and a commit in it. When you have some code, you should push it to Gerrit. (That is covered in task T248232.) If you want to make changes, you don't create new commits in the branch. Instead you amend the existing commit. You can amend the commit many times. When you're happy with the work, you merge the commit to the master branch.
This task will introduce you to the Gerrit workflow of amending a commit. I have created a commit and pushed it to Gerrit: 585759.
Your task is to fetch the patch to your machine, add your Phabricator username to tests/selenium/README.md, amend the commit and push it back to Gerrit.
Go to the mediawiki/core folder in your terminal. (You have cloned the repository in T248232.)
Fetch the patch.
git review -d 585759
Add your Phabricator username to tests/selenium/README.md. Use your favorite text editor.
Amend the commit. Do not change the commit message.
git add tests/selenium/README.md git commit --amend
Push the amended commit back to Gerrit.
git review -R
For more information see Gerrit/Tutorial: Amending a change (your own or someone else's).