The aim here is to practice or learn some basic git commands in a functional (albeit very simple) code base.
In the steps below you'll cover add commit checkout branch push merge log reset.
At the top of the script are some doctest. Lines that start with >>> will be tested to match the following line. As you add functions, uncomment the #>>> lines to >>> to make sure the code works.
The aim here is git commands though, not python code.
To run the tests execute:
python -m doctest temp_converter.py
No output means things worked. For verbose output add -v
python -m doctest -v temp_converter.py
The bottom of the script has very a simple CLI, which we'll add functionality to. To start run simply with a numeric input value:
python temp_converter.py 23.2
To start we'll add a celcius_to_fahrenheit function to the script. To do this, we'll first create a new branch. This can be a "feature branch" as we add a new feature to the code.
git checkout -b feature
git checkout changes to an alternate branch, or commit or tag. Usually you'll use it for switching branches.
-b will create and checkout a new branch
From this point we can make our code edits, replace the current place_holder() function with your new celcius_to_fahrenheit(). when we're happy we'll "stage" the edits using
git add temp_converter.py
If we're happy and want to "commit" to the edits, we can add a comment for the log.
git commit -m "add C to F function"
To backup or share these local edits, we can now push to the remote repository.
git push
Full commands for task 1
git checkout -b feature1
def celcius_to_fahrenheit(celcius):
return (celcius * 9/5) + 32
python -m doctest temp_converter.py
python temp_converter.py 68
git add temp_converter.py
git commit -m "add C to F function"
git push
Now lets go back to our main branch. We don't need to create this time so just checkout with no flags.
Let's take a look at git status to see which branch we're on, and git log to see the history.
Take a look at your file. It should have reverted back to the original. You can switch back and forth to the new branch now wih checkout and your branch name.
Full commands for task 1 wrap up
git checkout main
git checkout feature1
git status
git log
Make sure we're back on main branch before starting. Let's create another new feature branch. Name it feature2 or whatever you want.
This time let's add a celcius_to_kelvin, like before replace the place_holder() with your new function and then add another kelvin_to_celcius function. Your file at this time should not support celcius_to_fahrenheit that's still on feature1 only.
When the code is done, add the file to stage the edits and if happy commit the edits with a useful comment.
Check the status of where we're at and then let's push up to github again.
Full commands for task 2
git checkout main
git checkout -b feature2
..edit code...
git diff
git status
git add temp_converter.py
git commit -m "add kelvin support"
git status
git push
Open up a PR for feature1 branch on github.com. Take a look at the changes, etc.
Then we'll merge this branch in to main.
On your local computer, git checkout main and git pull to see the remote changes.
Check the log to see how the history has been merged.
Back on github.com, open up another PR for feature2 branch. We should now run into a merge conflict. Resolve the conflict through the browser, add a commit message about the merge.
The main branch should now include all 4 functions and the log should show a combined history.
On your local computer, use git fetch, git status and git pull to synchronize edits with the remote repo.
Local commands for task 3
git checkout main
git diff feature1
git merge feature1
git diff feature2
git merge feature2
... resolve conflict ...
git commit -m "merge feature2 branch"
git status
git push
Still on the main branch, let's add the last 2 functions. fahrenheit_to_kelvin and kelvin_to_fahrenheit. When we're happy, add and commit those edits (Do Not Push).
Now, we've made edits directly to the main branch. In big repos, this is a no-no, we want to make edits on branches which are reviewed and then merged. That detail doesn't matter too much, but we want to undo those commit(s) but keep the work.
Check git log to see how many commits we want to "undo". Then
git reset HEAD~1 or git reset <hash>.
This will apply a mixed reset, where the edits are kept but unstaged and the commit is undone.
A hard reset undoes the edits as well, all progress is forgotten.
A soft reset keeps the edits and keeps them staged, similar to mixed.
Now git status should say we have "changes not staged for commit", let's create a feature3 branch. Then add and commit those changes to that branch.
The product team has decided that all temperatures will be in °Ré and that no conversions will be available. Delete all the code, we don't want to maintain that and replace with a simple print("Please use °Réaumur, no conversions provided").
Add and commit this very important change.
The product team had some coffee and realised the previous changes weren't optimal. They would like all the previous functionality restored.
Use git log to check the commit hash or number of commits to undo, then git reset --hard HEAD~1 or git reset --hard <hash>
To merge the extra functions into main again, open up a PR on github.com check the changes and merge.
Full commands for task 4
...edit code...
git add .
git commit -m "add f to k support"
git log
git reset HEAD~1
git checkout -b feature3
git add .
git commit -m "add f to k support"
...edit code...
git add .
git commit -m "purge all code only support °Réaumur"
git log
git reset --hard HEAD~1
git checkout main
git diff feature3
git merge feature3
git push