Design Systems + Git = Success - Clarity Conference 2018

Design Systems + Git = Success
Katie Sylor-Miller
Staff Engineer, Etsy Frontend Systems
twitter: @ksylor

Agenda
Intros
Fundamental Concepts
Data Structures
Workflow in-depth
Viewing and changing history
Managing and sharing repos
Problems, solutions, and tips

Your name
Your preferred pronouns
Where do you work?
How comfortable are you with Git?
What’s your favorite NYC experience so far?
Intros

Agenda
Intros
Data Structures
Workflow in-depth
Managing and Sharing repos
Problems, solutions, and tips

What is Git?
Why Git?
Git vs. Github
Exercise 1

Git is a
Version Control System
(VCS)

Provide a way to store the history of files:
• when they changed
• how they changed
• who changed them
• why they changed
Version Control Systems

Versioning: the not awesome way
my-file.psd my-file-v2.psd my-file-v3.psd my-file-
FINAL.psd
my-file-FINAL-
FINAL-for-real-
this-time.psd

Versioning: the awesome Git way
my-file.psd
v5
v4
v3
v2
v1

Repositories (repos)
by Etsy seller IliaSCoolVintage

Repositories (repos)
happy.scss
pretty.scss
app.js
hi-world.js
fun.js
/css
cool.svg
/svg
README.md
v5
v4
v3
v2
v1
/Users/ksylor/my-git-repo

Git is a distributed
Version Control System

Distributed Version Control
• A “cloned” copy of the entire repository - including all files,
metadata, and it’s full history - is mirrored on each user’s
local host machine.
• Usually (but not always!) there is a central/canonical copy of
the repository stored in a remote git server called origin.
• You can configure multiple remote repositories, even
another repo on your machine can be a remote!

remote
my
local
local local local local

ksylormiller:~$
20
Copy a repository

ksylormiller:~$ git clone https://github.com/ksylor/ohshitgit.git
Cloning into 'ohshitgit'...
remote: Enumerating objects: 28, done.
remote: Total 28 (delta 0), reused 0 (delta 0), pack-reused 28
Unpacking objects: 100% (28/28), done.
ksylormiller:~$
21
Copy a repository

remote origin
my
local

Pushing to a remote
remote origin
my
local

Pulling from a remote
remote origin
my
local

Benefits of Git
• Historical context - view and compare different versions of
files to understand what changed and why.
• Safety net - if you make a mistake, you can easily revert
back in time to a previous version of a file.
• Collaboration - multiple people can work on the same files
at the same time, then share their changes with each other.
• Conflict resolution - Git can resolve conflicts that arise
when multiple people make changes to the same file.

Benefits of Git for Design Systems
• Sandboxing - you can work on changes locally, without
affecting anyone else, until they are ready to be shared.
• Versioned releases - you can control when you are ready to
share code with other teams.
• Quality control - pull requests allow core team members to
review file changes before they end up in a release.
• Documentation - the Github interface has simple
documentation capabilities built-in.

Git
A tool for distributed
version control
(the stuff you do in the
command line)
A company that hosts
Git repos (with some
extra features)
(the stuff you do in the
github.com website)
Github

Cloning and Creating Repos
https://github.com/ksylor/clarity-workshop-exercises/
tree/master/exercise-1
Exercise 1

Commits
Branches
HEAD
History
Exercise 2
Data Structures

What’s in a commit
Each commit contains a few pieces of information:
• A snapshot of the entire repo
• Who made this change
• When this change was made
• A message describing the commit
• A pointer to the previous commit

What’s in a commit
SHA-1
Unique
40-char
hash
Each commit contains a few pieces of information:

Commit hashes
a4df41a8045877d50396d00113598e47f6ad10ef
aec561108fd86412c2a9083d7d95ed1668d2f4e4
6dab6a712177cf2dd2cf8b79a2cee24351be60eb
1a3531222242241153ac8a76b752d5f525a99d2c
912bde5d4e5e962269ddff87da83cc5ce55e75d0v5
v4
v3
v2
v1

Commit hash abbreviations
a4df41a
aec5611
6dab6a7
1a35312
912bde5v5
v4
v3
v2
v1

by Etsy seller SwearsandStares

Mental model: branches are a linked list
a4df41aaec56116dab6a71a35312 912bde5
A B C D E

Mental model: branches are a linked list
A B C D E

Branches are a linked list reference
A4DF41A6DAB6A7
A B C D EA B C D E
master

Branches are a linked list reference text file
A4DF41A6DAB6A7
master
.git/refs/heads/master
912bde5d4e5e962269ddff87da83cc5ce55e75d0
A B C D E

ksylormiller:~/ohshitgit (master)$ git branch new-branch
46
Create a new branch

New branches are a new reference
A4DF41A6DAB6A7
master
new-branch
A B C D E

New branches are a new text file
A4DF41A
master
A B C D E
.git/refs/heads/master
.git/refs/heads/new-branch
new-branch

HEAD points to your currently checked-out branch
HEAD
a4df41aaec56116dab6a7 912bde5
master
new-branch
B C D E

HEAD is a reference to a reference
HEAD
A4DF41A6DAB6A7
master
new-branch
.git/refs/HEAD
ref: refs/heads/master
B C D E

WTF is the HEAD
• The HEAD decides what branch/commit will be the target of
your actions
• There is only one HEAD per repository
• The HEAD is unique to your local install of git
• The history of the HEAD is recorded, which gives you a way
to undo your work (more on this later)

ksylormiller:~/ohshitgit (master)$ git checkout new-branch
53
Change branches

HEAD points to your currently checked-out branch
HEAD
master
new-branch
.git/refs/HEAD
ref: refs/heads/new-branch
B C D E

ksylormiller:~/ohshitgit (master)$ git commit -m “Your message here”
55
Add a new commit to our branch

A new commit becomes the new HEAD
1668d2f
HEAD
master
new-branch
B C D E F

History is a linked list
1668d2fa4df41aaec56116dab6a7 912bde5
master
new-branch
B C D E F

History is a linked list tree
master
ca53f4f
1668d2f
a4df41a 912bde5
new-branch
3de21fa
C D E
F
G H

ca53f4f
1668d2f
fd4ab1a
912bde5
3de21fa
new-branch
86bcaed 2d3a4da
whee
3037cf2
master
44ff212
4aa3b5f
c1d2ea8 40648a8
5ae77a5
omg-stop
fd4ab1a
and-another
History is a linked list tree directed acyclic graph
f6e51fd
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S

Fundamental concepts: recap
• Commits are a unique snapshot of a repository at a single
point in time
• History is a linked list tree directed acyclic graph
• Branches are a reference to a single commit in history
• HEAD is a symbolic reference to your current working branch

Commits, Branches,
Refs and HEAD
https://github.com/ksylor/clarity-workshop-exercises/tree/
master/exercise-2
Exercise 2

Environments
A simple workflow
A complicated workflow
Exercise 3
A real workflow
Exercise 4
Workflows in depth

REMOTE/ORIGIN
Your machineGithub
LOCAL STAGING/INDEX WORKSPACE
Central server where
shared git repositories
are stored
--
Remotes typically are
“bare” - you can’t
directly modify them

REMOTE/ORIGIN
Your machineGithub

REMOTE/ORIGIN
Your machineGithub
Your local copy of the
remote git repository
--
Lives in a .git folder
inside your local copy
folder
--
Contains the entire
history of a remote repo
plus local changes

REMOTE/ORIGIN
Your machineGithub
Snapshot of changes to
the current branch that
you want to commit
--
Is a copy of all of the
files in the repo, not just
the changed files

REMOTE/ORIGIN
Your machineGithub
Where changes to
files are made
--
Analogous to the
physical directory
where files are stored
on disk

REMOTE/ORIGIN
Your machineGithub
MASTER

ksylormiller:~$ git clone https://github.com/ohshitgit/example.git
Cloning into 'fluent-example'...
remote: Counting objects: 12, done.
remote: Compressing objects: 100% (9/9), done.
Checking connectivity... done.
73
git clone

REMOTE/ORIGIN
Your machineGithub
MASTER MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
HEAD

REMOTE/ORIGIN
Your machineGithub
MASTER MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php

git status
is your BFF
by Etsy seller SmittenKittenKendall

ksylormiller:~/ohshitgit (master)$ git status
On branch master
Your branch is up-to-date with ‘origin/master'.
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
modified: bar.php
no changes added to commit (use "git add" and/or "git commit -a”)
77
git status is your BFF

git status and
git diff
are your BFFs
by Etsy seller SmittenKittenKendall

ksylormiller:~/ohshitgit (master)$ git diff
diff --git a/bar.php b/bar.php
index f81fce0..bdd3cb3 100644
--- a/bar.php
+++ b/bar.php
@@ -1 +1,4 @@
this is a file
-with nothing in it
+with some stuff in it
79
git diff is your other BFF

REMOTE/ORIGIN
Your machineGithub
git diff
compares changes 
in workspace
to changes 
(if any) in index
git diff --staged
compares changes 
in index to HEAD 
(e.g. current state 
of your checked-out 
branch)
git diff HEAD
compares changes 
in both index and 
workspace to HEAD

ksylormiller:~/ohshitgit (master)$ git add bar.php
81
git add

On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: bar.php
83
git status (again)

On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: bar.php
modified: bar.php
85
git status (I told you it was our BFF)

ksylormiller:~/ohshitgit (master)$ git commit -m "Meaningful commit message"
[master 4875652] Meaningful commit message
1 file changed, 1 insertion(+)
86
git commit

REMOTE/ORIGIN
Your machineGithub
MASTER
MASTER
baz.php
foo.php
bar.php

ksylormiller:~/ohshitgit (master)$ git push
Counting objects: 4, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 328 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To https://github.com/ksylor/fluent-example.git
4875652..97e8858 master -> master
88
git push

REMOTE/ORIGIN
Your machineGithub
MASTER
MASTER

REMOTE/ORIGIN
Your machineGithub
MASTER MASTER

But… it’s almost
never that simple

REMOTE/ORIGIN
Your machineGithub
MASTER
ORIGIN/
MASTER
MASTER

ksylormiller:~/ohshitgit (master)$ git fetch
From https://github.com/ksylor/fluent-example
97e8858..8a97966 master -> origin/master
95
git fetch

ksylormiller:~/ohshitgit (master)$ git merge origin/master
97
git merge

Merge remote-tracking branch 'origin/master'
# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
#
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.
~
~
~
~
"~/ohshitgit/.git/MERGE_MSG" 7L, 293C
98
oh god we’re in vim

ksylormiller:~/ohshitgit (master)$ git merge origin/master
Updating 97e8858..8a97966
Fast-forward
README.md | 2 ++
1 file changed, 2 insertions(+)
create mode 100644 README.md
99
git merge complete

ksylormiller:~/ohshitgit (master)$ git pull
Merge made by the 'recursive' strategy.
README.md | 2 ++
create mode 100644 README.md
101
git pull == git fetch && git merge

remote: Resolving deltas: 100% (2/2), completed with 1 local object.
8a97966..91f6790 master -> master
103
git push

REMOTE/ORIGIN
Your machineGithub
ORIGIN/
MASTER
MASTERMASTER

ksylormiller:~/ohshitgit (master)$ git rebase origin/master
First, rewinding head to replay your work on top of it...
Applying: Meaningful commit message
107
git rebase

ksylormiller:~/ohshitgit (master)$ git pull --rebase
First, rewinding head to replay your work on top of it...
Applying: Meaningful commit message
110
git pull --rebase == git fetch && git rebase

f6e51fd..3c2335c master -> master
112
git push

I solemnly swear
never to run git pull

Workflows in depth: recap
• We interact with git repos via remote (bare) servers, and on
your machine w/ it’s local copy, workspace, and staging
area
• git add takes a snapshot of a changed file in it’s current
state & adds it to staging
• git status and git diff your BFFs
• We interact with the remote via tracking branches, another
kind of reference

Workflows in depth: recap
• git pull = git fetch && git merge  
creates a new merge commit (gross! vim! no!)
• git pull --rebase = git fetch && git rebase
replays your work at the tip of master (beautiful! yes!)

Workflow
https://github.com/ksylor/clarity-workshop-exercises/
tree/master/exercise-3
Exercise 3

ksylormiller:~/ohshitgit (master)$ git checkout -b feature-branch
121
Create & checkout a branch

REMOTE/ORIGIN
Your machineGithub
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
HEAD
FEATURE
-BRANCH
MASTER

REMOTE/ORIGIN
Your machineGithub
MASTER
baz.php
foo.php
bar.php
FEATURE
-BRANCH
MASTER
baz.php
foo.php
bar.php

ksylormiller:~/ohshitgit (feature-branch)$ git add bar.php
124
git add

REMOTE/ORIGIN
Your machineGithub
MASTER
baz.php
foo.php
FEATURE
-BRANCH
MASTER
baz.php
foo.php
bar.phpbar.php

ksylormiller:~/ohshitgit (feature-branch)$ git status
On branch feature-branch
modified: bar.php
no changes added to commit (use "git add" and/or "git commit -a”)
126
git status

ksylormiller:~/ohshitgit (feature-branch)$ git diff
--- a/bar.php
+++ b/bar.php
@@ -1 +1,4 @@
this is a file
-with nothing in it
+with some stuff in it
127
git diff

ksylormiller:~/ohshitgit (feature-branch)$ git commit -m "Meaningful commit
message"
[feature-branch 4875652] Meaningful commit message
128
git commit

REMOTE/ORIGIN
Your machineGithub
FEATURE-
BRANCH
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
MASTER

REMOTE/ORIGIN
Your machineGithub
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
MASTER
FEATURE-
BRANCH

ksylormiller:~/ohshitgit (feature-branch)$ git push -u
Writing objects: 100% (9/9), 820 bytes | 820.00 KiB/s, done.
remote: Resolving deltas: 100% (1/1), done.
remote:
remote: Create a pull request for 'feature-branch' on GitHub by visiting:
remote: https://github.com/ksylor/clarity-workshop-example/pull/new/feature-branch
remote:
To https://github.com/ksylor/clarity-workshop-example.git
* [new branch] feature-branch -> feature-branch
Branch feature-branch set up to track remote branch feature-branch from origin.
131
push a new branch

REMOTE/ORIGIN
Your machineGithub
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
MASTER
FEATURE-
BRANCH
FEATURE-
BRANCH
ORIGIN/
FEATURE-
BRANCH

by Etsy seller ninjagrl
Pull requests
(PRs)

Pull Requests (PRs)
• An additional feature on top of core Git functionality.
• PRs do a diff comparison between two branches - usually
comparing a feature branch to the current state of master.
• Allows teammates to review code, ask questions, find
possible bugs before code hits production.
• Provides a nice visual way to confirm that the code in your
branch contains only the changes that you want!

Reviewing a PR
by Etsy seller SimplyPerfectDesignL

Merging a PR
by Etsy seller InkinPark

REMOTE/ORIGIN
Your machineGithub
MASTER
FEATURE-
BRANCH

ksylormiller:~/ohshitgit (feature-branch)$ git fetch
From https://github.com/ksylor/fluent-example
97e8858..8a97966 master -> origin/master
ksylormiller:~/ohshitgit (master)$
162
git fetch

ksylormiller:~/ohshitgit (feature-branch)$ git checkout master
On branch master
Your branch is behind 'origin/master' by 2 commits, and can be fast-
forwarded.
(use "git pull" to update your local branch)
nothing to commit, working tree clean
163
checkout master

ksylormiller:~/ohshitgit (master)$ git pull --rebase
Updating 74877c3..2ea524f
Fast-forward
fun.txt | 2 ++
Current branch master is up to date.
164
update master

ksylormiller:~/ohshitgit (master)$ git merge --squash feature-branch
Squash commit -- not updating HEAD
Automatic merge went well; stopped before committing as requested
165
Squash merging

REMOTE/ORIGIN
Your machineGithub
MASTER
ORIGIN/
MASTER
FEATURE-
BRANCH
baz.php
foo.php
bar.php
MASTER

ksylormiller:~/ohshitgit (master)$ git commit -m “Merge feature-branch”
[master 4875652] Merge feature branch
167
git commit

REMOTE/ORIGIN
Your machineGithub
MASTER
ORIGIN/
MASTER
baz.php
foo.php
bar.php
MASTER

8a97966..91f6790 master -> master
170
git push

REMOTE/ORIGIN
Your machineGithub
MASTER ORIGIN/
MASTER
MASTER

Feature branches and Pull Requests
master/exercise-4
Exercise 4

Viewing history
Changing history
Exercise 5

View the history of a branch
1668d2f
HEAD
master
B C D E F

ksylormiller:~/ohshitgit (master)$ git log
commit 3c2335c50a1ad48a283a475e3d3f9ac445a20ff5
Author: Katie Sylor-Miller <katie@ohshitgit.com>
Date: Thu Jun 8 23:42:05 2017 -0400
Another awesome commit
A detailed message about this commit goes here
commit f6e51fdd6650c7bbc39895c0392ec6a9fb5a9c15
Author: Someone else <someone@ohshitgit.com>
Date: Thu Jun 8 23:39:36 2017 -0400
Oh hai this is a change
commit 4f9a80ff7732f252ffbe7841e96748707da1a78d
178
git log

ksylormiller:~/ohshitgit (master)$ git log --oneline
3c2335c Another awesome commit
f6e51fd Oh hai this is a change
91f6790 Meaningful commit message
4f9a80f Fake commit messages are hard
8a97966 Is anyone actually reading this?
97e8858 Lolz
4875652 Hello world
179
Short history

by Etsy seller Birdwoodshack
git reflog
is your magic
time machine

ksylormiller:~/ohshitgit (master)$ git reflog
3c2335c HEAD@{0}: rebase finished: returning to refs/heads/master
3c2335c HEAD@{1}: pull --rebase: lolz
f6e51fd HEAD@{2}: pull --rebase: checkout f6e51fdd6650c7bbc39895c0392ec6a9fb5a9c15
f4f4d99 HEAD@{3}: reset: moving to HEAD@{4}
f6e51fd HEAD@{4}: reset: moving to HEAD~
1ecad3a HEAD@{5}: rebase finished: returning to refs/heads/master
1ecad3a HEAD@{6}: rebase: lolz
f6e51fd HEAD@{7}: rebase: checkout origin/master
f4f4d99 HEAD@{8}: commit: lolz
4f9a80f HEAD@{9}: commit: Another awesome commit
4875652 HEAD@{10}: commit: Meaningful commit message
181
git reflog

HEAD notation
• HEAD@{index} : go to a specific point
• HEAD~ == HEAD@{currentindex+1} : back one action
• HEAD~x == HEAD@{currentindex+x} : back x actions
• Or, you can always reference by hash

ksylormiller:~/ohshitgit (master)$ git show HEAD@{8}
commit f4f4d996d44bbf824cdd22ace9e6d154d27c9a5d
Author: Katie Sylor-Miller <katie@ohshitgit.com>
Date: Thu Jun 8 23:42:05 2017 -0400
lolz
--- a/bar.php
+++ b/bar.php
@@ -1 +1,4 @@
this is a file
-with nothing
+with some lolz
183
git show

ksylormiller:~/ohshitgit (master)$ git checkout HEAD@{8}
Note: checking out 'HEAD@{8}'.
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:
git checkout -b new_branch_name
HEAD is now at a4df41a... Merge remote-tracking branch 'origin/master'
ksylormiller:~/ohshitgit (master) ((detached from a4df41a))$
184
git checkout

A detached HEAD is when your
HEAD points directly to a
commit or a tracking branch
(not an editable branch)
WTF is a detached HEAD?

post-checkout detached HEAD
1668d2f
HEAD
master
B C D E F

• Checking out an existing branch - throws away any work you
might have done
• Create a new branch from this state - allows you to save any
work, or create a branch from any point in time
Re-attaching the HEAD

Checkout all the things
Checkout can be used to move the HEAD OR checkout can also
change the state of a file in the workspace (w/o moving HEAD)
• Discard workspace changes to a file or directory 
git checkout -- path/to/file/or/dir/
• Reset file or dir to state in history (then commit to save!) 
git checkout <commit hash> —-path/to/file/or/dir/
• Get state of a file or dir from another branch (then commit) 
git checkout other-branch --path/to/file/or/dir/

Changing history of a branch
1668d2f
HEAD
a4df41aaec56116dab6a7
master
B C D E F
912bde5

git reset brings you back to a
previous state in history,
undoing everything that
changed between now and then
Hit the reset button

ksylormiller:~/ohshitgit (master)$ git reflog
1668d2f HEAD@{0}: rebase finished: returning to refs/heads/master
3c2335c HEAD@{1}: pull --rebase: lolz
912bde5 HEAD@{2}: pull --rebase: checkout
f6e51fdd6650c7bbc39895c0392ec6a9fb5a9c15
f4f4d99 HEAD@{3}: commit: lolz
192
git reflog

ksylormiller:~/ohshitgit (master)$ git reset HEAD@{3}
Unstaged changes after reset:
M foo.php
193
git reset

Three basic types of resetting
Discards the changes
from the affected
commits
Leaves the changes
from the affected
commits in the
workspace (default)
--hard--mixed--soft
Leaves the changes
from the affected
commits in staging

Post-reset
1668d2f
HEAD
a4df41aaec56116dab6a7
master
Changes move
to the index
or workspace
or discarded
912bde5
B C D E F

Disclaimer: never
change public history

git revert creates a new commit
that undoes the changes in the
specified commit(s)
Undo a public commit

ksylormiller:~/ohshitgit (master)$ git revert f4f4d99
198
git revert

Revert "lolz"
This reverts commit f4f4d996d44bbf824cdd22ace9e6d154d27c9a5d.
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Your branch is ahead of 'origin/master' by 3 commits.
# (use "git push" to publish your local commits)
#
# Changes to be committed:
# modified: bar.php
#
~
"~/ohshitgit/.git/COMMIT_EDITMSG" 14L, 450C
199
ugh, vim again

ksylormiller:~/ohshitgit (master)$ git revert
f4f4d996d44bbf824cdd22ace9e6d154d27c9a5d
[master b483271] Revert "lolz"
1 file changed, 3 deletions(-)
200
git revert complete

Post-revert
1668d2f
HEAD
a4df41aaec5611 b75fb8b912bde5
master
reverts changes from
C D E F G

Viewing and changing history: recap
• git log shows the history of your branch
• git reflog shows the history of the HEAD aka the magic time
machine
• git checkout lets you view a previous state of the repo in a
read-only “detached HEAD” state
• git reset lets you go back in time and change things
• git revert creates a new commit to undo changes

Viewing and Changing History
master/exercise-5
Exercise 5

Versioning
npm Packages
Releases
Documentation
Issues
Managing and sharing repos

Why version your design system?
• You won’t get it perfect the first time, so you need to plan
for how to handle changes to your code.
• With versioning, you make controlled releases of changes to
your code, and consuming teams can chose which version
they use, and when and how to upgrade (or not!).
• Versions allow you to release breaking changes, e.g. a
change that will break existing uses of a pattern, without
disrupting existing users.

Semver (Semantic Versioning)
0.1.0
Major Release
Changes are not 
backwards-
compatible with
prior versions
More info at semver.org
Minor Release
New functionality 
is backwards- 
compatible with  
prior versions
Patch Release
Only contains 
bug fixes, which 
are backwards- 
compatible

Semver (Semantic Versioning)
0.1.0-alpha
More info at semver.org
Optional Pre-Release Version
Indicates that this 
version is unstable or 
might change before 
the “real” release

ksylormiller:~/ohshitgit (master)$ npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.
See `npm help json` for definitive documentation on these fields
and exactly what they do.
Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.
Press ^C at any time to quit.
211
npm init

package name: (clarity-workshop-example)
version: (1.0.0) 0.1.0
description: An example npm package for clarity workshop
entry point: (index.js)
test command:
git repository: (https://github.com/ksylor/clarity-workshop-example.git)
keywords:
author: Katie Sylor-Miller
license: (ISC)
About to write to /Users/ksylormiller/clarity-workshop-example/package.json:
212
npm init (cont)

{
"name": "clarity-workshop-example",
"version": "0.1.0",
"description": "An example npm package for clarity workshop",
"main": "index.js",
"scripts": {
"test": "echo "Error: no test specified" && exit 1"
},
"repository": {
"type": "git",
"url": "git+https://github.com/ksylor/clarity-workshop-example.git"
},
"author": "Katie Sylor-Miller",
"license": "ISC",
"bugs": {
"url": "https://github.com/ksylor/clarity-workshop-example/issues"
},
"homepage": "https://github.com/ksylor/clarity-workshop-example#readme"
}
Is this OK? (yes) yes
213
npm init (cont)

On branch master
Your branch is up-to-date with 'origin/master'.
Untracked files:
(use "git add <file>..." to include in what will be committed)
package.json
nothing added to commit but untracked files present (use "git add" to track)
214
package.json

ksylormiller:~/ohshitgit (master)$ git add . && commit -m “add package.json”
[master 995198f] add package.json
create mode 100644 package.json
Writing objects: 100% (3/3), 554 bytes | 554.00 KiB/s, done.
To https://github.com/ksylor/clarity-workshop-example.git
2ea524f..995198f master -> master
215

ksylormiller:~/someotherproject (master)$ npm install --save-dev https://
github.com/ksylor/clarity-workshop-example/archive/v0.1.1.tar.gz
npm notice created a lockfile as package-lock.json. You should commit this
file.
+ clarity-workshop-example@0.1.0
added 1 package from 1 contributor and audited 1 package in 1.325s
found 0 vulnerabilities
221
add your package as a dependency to another project

Versions and releases
master/exercise-6
Exercise 6

Problem: Committing
the wrong thing

• Set up your command line to show you what branch you are on
• Remember git status and git diff your BFFs
• Understand how staging works (subsequent changes to a file
are not reflected
• Use a feature branch so you don’t accidentally commit to
master!
Avoid the problem: Committing the wrong thing

ksylormiller:~/ohshitgit (master)$ git commit --amend
237
Fix the problem: Entering the wrong commit message

238
vim again :(
My wrong commit message
# On branch master
#
# modified: bar.php
#
~

239
vim again :(
My right commit message
# On branch master
#
# modified: bar.php
#
~

ksylormiller:~/ohshitgit (master)$ git commit --amend
[master f0c2e62] My correct commit message
1 file changed, 3 deletions(-)
240
Fix the problem: Entering the wrong commit message

ksylormiller:~/ohshitgit (master)$ git add file/i/forgot/to/commit.ext
ksylormiller:~/ohshitgit (master)$ git commit --amend —no-edit
[master 014035a] My commit message
1 file changed, 1 insertion(+), 3 deletions(-)
241
Fix the problem: Forgetting to commit a file, or just one small change

Problem: Committing
to the wrong branch

Your machine
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
STASH

Your machine
MASTER
baz.php
foo.php
bar.php
baz.php
foo.php
bar.php
STASH
YOUR
CHANGES
HEAD
COMMIT

ksylormiller:~/ohshitgit (master)$ git stash
Saved working directory and index state WIP on master: 3c2335c lolz
249
add to the stash

ksylormiller:~/ohshitgit (master)$ git stash list
stash@{0}: WIP on master: 3c2335c lolz
stash@{1}: WIP on feature-branch: a682e3a my feature rocks
stash@{2}: WIP on master: f6e51fd oh hai
stash@{3}: WIP on master: 6d4cf2d something else
252
git stash list

ksylormiller:~/ohshitgit (master)$ git stash save “started on ticket OSG-42”
253
git stash save a better message

ksylormiller:~/ohshitgit (master)$ git stash list
stash@{0}: WIP on master: started on ticket OSG-42
stash@{1}: WIP on feature-branch: a682e3a my feature rocks
stash@{2}: WIP on master: f6e51fd oh hai
stash@{3}: WIP on master: 6d4cf2d something else
254
git stash list again

ksylormiller:~/ohshitgit (master)$ git stash show -p
index ebc0bc8..a44188c 100644
--- a/bar.php
+++ b/bar.php
@@ -1,4 +1,8 @@
+aaaaaaa
+fdfjdklfjdsalf;j
fdafsdfas
fdafdsfdas
fdfadasfdas
this is a file
255
viewing a stash entry

ksylormiller:~/ohshitgit (master)$ git stash pop
modified: bar.php
ksylormiller:~/ohshitgit (master)$ git stash apply
256
pop changes back off the stack

Stash tips and tricks
• git stash --keep-index - leaves the index intact after
stashing changes.
• git stash --patch - opens interactive mode for deciding
what chunks of what files to stash.
• git stash —include-untracked - save untracked files
(w/o this flag untracked files are only included if they are in
the index)

ksylormiller:~/ohshitgit (master)$ git reset HEAD~ —soft
ksylormiller:~/ohshitgit (master)$ git stash
ksylormiller:~/ohshitgit (master)$ git checkout feature-branch
Switched to branch ‘feature-branch’
259
Option 1: Fix committing to the wrong branch

ksylormiller:~/ohshitgit (feature-branch)$ git stash pop
modified: baz.php
modified: foo.php
no changes added to commit (use "git add" and/or "git commit -a")
Dropped refs/stash@{0} (3c0529b7e598984b78647f391eab1ca6fd7897a0)
ksylormiller:~/ohshitgit (feature-branch)$ git commit -am “on the right branch
now”
260

REMOTE/ORIGIN
Your machineGithub
MASTER
FEATURE-
BRANCH
MASTER
COMMIT ON
THE WRONG
BRANCH :(

ksylormiller:~/ohshitgit (master)$ git log
// get the hash for your commit
ksylormiller:~/ohshitgit (master)$ git checkout feature-branch
ksylormiller:~/ohshitgit (feature-branch)$ git cherry-pick 3c2335c
[feature-branch 16759ae] lolz
Date: Thu Jun 8 23:42:05 2017 -0400
263

REMOTE/ORIGIN
Your machineGithub
MASTER MASTER
16759ae
3c2335c
FEATURE-
BRANCH

ksylormiller:~/ohshitgit (feature-branch)$ git checkout master
ksylormiller:~/ohshitgit (master)$ git reset --hard HEAD~
HEAD is now at fcebc22 my prior commit message
On branch master
Your branch is up-to-date with 'origin/master'.
nothing to commit, working tree clean
265

ksylormiller:~/ohshitgit (feature-branch)$ git rebase -i HEAD~2
269
Avoid the problem: Combine commits before rebasing

REMOTE/ORIGIN
Your machineGithub
MASTER
ORIGIN/
MASTER
FEATURE-
BRANCH
MASTER

pick 2f5bae4 example feature branch
pick 0ee2a20 Another commit
# Rebase aaff258..0ee2a20 onto aaff258
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
~
"~/ohshitgit/.git/rebase-merge/git-rebase-todo" 20L, 670C
271
Interactive rebase

pick 2f5bae4 example feature branch
fixup 0ee2a20 Another commit
# Rebase aaff258..0ee2a20 onto aaff258
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
~
"~/ohshitgit/.git/rebase-merge/git-rebase-todo" 20L, 670C
272
Interactive rebase

ksylormiller:~/ohshitgit (feature-branch)$ git rebase -i HEAD~2
[detached HEAD a682e3a] example feature branch
3 files changed, 5 insertions(+)
Successfully rebased and updated refs/heads/feature-branch.
273
Avoid rebasing problems: combine commits

ksylormiller:~/ohshitgit (master)$ git merge-base master feature-branch
3c2335c50a1ad48a283a475e3d3f9ac445a20ff5
ksylormiller:~/ohshitgit (feature-branch)$ git rebase -i 3c2335c
275
If you don’t know how many commits to go back

ksylormiller:~/ohshitgit (master)$ git merge --squash feature-branch
Squash commit -- not updating HEAD
Automatic merge went well; stopped before committing as requested
278
Squash merging

• Update your local master and origin/master all.the.time.
• Rebase your feature branches to stay up to date
• Periodically squash feature branch commits to reduce the
number of conflicts to resolve (esp. when rebasing)
• Communication with teammates
• If things don’t seem right, abort!
Avoid the problem: Merge conflicts

ksylormiller:~/ohshitgit (master)$ git config merge.tool <toolname>
ksylormiller:~/ohshitgit (master)$ git mergetool
284
Use a visual merge tool

Merge master into your
feature branch
Rebase master against
your feature branch
Merge your feature
branch into master
Rebase your feature
branch against master
Merge and rebase in the right direction
DON’T DO

ksylormiller:~/ohshitgit (master)$ git merge feature-branch
Auto-merging conflict_file.txt
CONFLICT (content): Merge conflict in conflict_file.txt
Automatic merge failed; fix conflicts and then commit the result.
ksylormiller:~/ohshitgit (master)$ cat conflict_file.txt
<<<<<<< HEAD
this code
is from master
=======
this code
is from feature-branch
>>>>>>>> d34367
287
Conflict markers

ksylormiller:~/ohshitgit (master)$ git diff --check
foo.php:1: leftover conflict marker
foo.php:5: trailing whitespace.
+fdfakadsfldjfasd^M
289
check your diffs before committing!

Avoiding & getting out of messes: Recap
• Always be committing - commits are cheap and easy to use!
• git commit --amend for when you mess up a commit
• Always be branching - feature branch workflow FTW
• Stay up to date
• Squash branches into a single commit before rebasing
• Squash merge back into master
• Use a visual merge tool whenever you can

If all else fails
ohshitgit.com

Design Systems + Git = Success - Clarity Conference 2018

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