Add support for `git merge --squash {branch}`

[gatsbimantico]

Being a popular option in Github to squash and merge, it would be interesting to add support for this option.

Initial scenario After running git checkout -b feat;git commit;git checkout main;

C2 (feat)
C1 (main) *

With merge --no-ff After running git merge --no-ff feat

C2 (feat) ─┐
C1 ────────┴─ C3 (main) *

With merge --squash After running git merge --squash feat

C2 (feat)
C1 ────────── C3 (main) *

This equivalent to just git commit -m "Squashed merge branch 'feat' into 'main'" as the connection with the C2 node is lost, and further git branch -D feat will leave C2 being not connected and ready to prune. This will show how you destroy history by using squash.

[netlify[bot]]

✅ Deploy Preview for xenodochial-hugle-b9ec84 ready!

Name	Link
🔨 Latest commit	30a50cf4c027a5c75a7a1e07d66d18956dc29cf9
🔍 Latest deploy log	https://app.netlify.com/sites/xenodochial-hugle-b9ec84/deploys/6386c18ad546a70009ee918b
😎 Deploy Preview	https://deploy-preview-1035--xenodochial-hugle-b9ec84.netlify.app/
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[pcottle]

Wow really awesome that you put up the functionality yourself! And figured out the somewhat gross/obtuse ways we parse command options and pass them around 🥴

Thanks a bunch for the test as well!

[pcottle]

(it's still in draft but ready to merge it whenever, unless you also want to add a lesson slide for it)

[gatsbimantico]

Hello @pcottle Thank you for this app ❤️ The code was really easy to follow, it's very clean.

I was just manually testing it now. While we can do git merge --no-ff side it seems to need two arguments for squash git merge --squash main side So I'll try to fix that.

I don't feel like I can put together a lesson for it. I guess it will be an initial state with a couple of branches, and a final state with just main, so you have to use merge --squash to merge to main, then branch -D some-branch to remove references and gc to prune the tree. Do you want to give it a go?

[pcottle]

yeah I can try to add a lesson once this lands (if folks are interested)

[gatsbimantico]

Thank you, that change worked. Now I understand why the value of the first argument seemed to not be used.

There's something funny with the tests, it might be related to the depth of the objects being compared. Also the error messages are not helpful because the assertion is just testing for truthy.

But I think this improvement is ready to go 🎉

[pcottle]

Awesome! this looks ready to go, I'll merge and push the site now

Also the error messages are not helpful because the assertion is just testing for truthy.

Yeah unfortunately it's just checking if the tree is in the expected state; theres no helpful debug message if that assertion is incorrect :/

[pcottle]

It's live! https://learngitbranching.js.org/?NODEMO&command=gc;%20git%20checkout%20-b%20side%20C1;%20git%20commit;%20git%20switch%20main;%20git%20merge%20side%20--squash