Mohamed Halawa
Mohamed Halawa

Mohamed Halawa

Enough Talks about Good Commit Message, Enforce or validate it!

Enough Talks about Good Commit Message, Enforce or validate it!

Git commits are the backbone for the historical overview of our projects. we need to keep it clean, structured, and informative

Mohamed Halawa
·Jun 6, 2022·

6 min read

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Table of contents

Why Commit Messages are such a big deal?

Version Control Systems were invented with the backway mechanism in mind, that’s represented By:

  • Commit ID e.g. 6e24e45
  • Commit Message e.g. fix a bug (please don’t do this 😓)
  • A State (after a change)

As time passes by, you eventually have to take a look at some changes that were made in the past. either you want to find out:

  • When some bug got introduced
  • or who created a piece of code

It should all be ready for the take when looking at the revision history.

The Art of Writing a Bad Commit

To write a Bad Commit as a Pro, you’ll need to follow One Rule:

A Bunch of empty words to bypass the basic validation of git (a commit message is required)

Examples

Example 1

image.png

Oh, thanks for letting everyone know that (whatever happened there) is still in progress even though it’s 2022 Now! (next year will be still in progress too)

Example 2

image.png

  • Thanks for your efforts. But, we already know that it’s a commit. So It has “CHANGES”
  • And What did you mean by 161 ?! Is it the police number? A ticket number?
  • If so, Which board does it belong to? Is it even a Jira Board?
  • What are the business rules behind this?
  • Does the author still work here?
  • Who did replace his position? In which team?

The Special Type of a Bad Commit Messages

A Commit messages that take 3 minutes to read.

What makes a Good Commit?

  • ✔️ Build a habit of making good commits (It takes time!)
  • ✔️ Keep your Commits Small
  • ✔️ Keep the changes staged within a commit related somehow!
  • ✔️ Write a meaningful & Descriptive message

    ❕ If they cannot be related to each other by any means. Then, it means a new commit is needed!

What makes a Good Commit Message?

A Good Commit Message, Is the shortest readable and descriptive message that could provide anyone with all the significant references and information at any time.

  • ✔️ It has to be short, readable, and descriptive.
  • ✔️ It should mention significant references.

For example, JIRA Ticket Number would provide anyone with:

  • The User Story (Business Rules & Acceptance Criteria)
  • The Team behind the change (maybe you can ask for their help later)
  • Maybe technical documentation is mentioned somewhere there.
  • Whoever tested this, So you can blame later for accepting your buggy work. 😝 (Never Do this)

Why would I make a Good Commit?

So you’re wondering why would I waste my time doing all of this?

Remember when you had a tricky bug caused by a change that was made by someone who resigned 3 years ago, and the only information or references you had at this moment was the name of the author and a bunch of non-related changes within the commit, even the commit message was called “Count the Stars”?

Did you “Count the Stars”? Or Spent hours and hours trying to

  • investigate, change, run, debug, rollback, investigate again, run, debug, … it’s the mid of night already!
  • Congratulations! Now you can “Count the Stars”, 👏
  • Yet you still didn’t figure out the Root Cause of the Problem 🤷

No one is wasting your time, you do! By not spending a little more time keeping your version control history consistent. Not only your time, time of others as well!”

Conventional Commits

If you do agree now that we need a “Good Commit”, here is the good news!

Conventional Commits were designed to achieve a Good Commit Message in a way that could be Automated, Validated, Read, or Written. also, it dovetails with Semantic Versioning

The most important advantage of following such a specification is achieving a level of commit messages consistency between all teams:

  • No one has his own Signature for the Commit message
  • You don’t need to think about it twice!

Main Structural Elements

  1. fix: a commit of the type fix patches a bug in your codebase (this correlates with PATCH in Semantic Versioning).
  2. feat: a commit of the type feat introduces a new feature to the codebase (this correlates with MINOR in Semantic Versioning).
  3. BREAKING CHANGE: a commit that has a footer BREAKING CHANGE: or appends a ! after the type/scope, introduces a breaking API change (correlating with MAJOR in Semantic Versioning). A BREAKING CHANGE can be part of commits of any type.

Example

image.png

Why Use Conventional Commits

  • Automatically generating CHANGELOGs.
  • Automatically determining a semantic version bump (based on the types of commits landed).
  • Communicating the nature of changes to teammates, the public, and other stakeholders.
  • Making it easier for people to contribute to your projects, by allowing them to explore a more structured commit history.

Validating The Commit Message

Now as we have a Standardized format for our messages shared across all teams, we can use the commit-msg git hook to validate the commit message based on a specific regular expression.

So that, if the message does comply with our format it will pass. Otherwise, an error message will be returned to the user asking her/him to follow a certain format!

Example:

image.png

So what happened is I did try to commit with the arbitrary message, that doesn’t comply with the git hook regular expression.

Then it stopped me! and Nothing has been committed!

Git hook Code

So, what the git-hook does is execute a script in predefined cases. and to validate our commit message, I've used the commit-msg git hook which was made for that purpose! read more

For honesty, I borrowed this script from someone on medium.com and did a few modifications to suit my case, I struggle now to reach his article. so if it does seem familiar to you please mention his article in a comment!

#!/bin/sh
# list of Conventional Commits types
cc_types=("feat" "fix")
default_types=("build" "chore" "ci" "docs" "${cc_types[@]}" "perf" "refactor" "revert" "style" "test")
types=( "${cc_types[@]}" )

if [ $# -eq 1 ]; then
    types=( "${default_types[@]}" )
else
    # assume all args but the last are types
    while [ $# -gt 1 ]; do
        types+=( "$1" )
        shift
    done
fi



# the commit message file is the last remaining arg
msg_file="$1"

# join types with | to form regex ORs
r_types="($(IFS='|'; echo "${types[*]}"))"
# optional (scope)
r_scope="(\([[:alnum:] \/-]+\))?"
# optional breaking change indicator and colon delimiter
r_delim='!?:'
r_jira="(VIS-[[:digit:]]+) "
# subject line, body, footer
r_subject=" [[:alnum:]].+"
# the full regex pattern
pattern="^$r_jira$r_types$r_scope$r_delim$r_subject"
# Check if commit is conventional commit
if grep -Eq "$pattern" "$msg_file"; then
    exit 0
fi
echo "[Commit message] $( cat "$msg_file" )"
echo "
Your commit message does not follow Conventional Commits formatting
https://www.conventionalcommits.org/
Conventional Commits start with one of the below types, followed by a colon,
followed by the commit message:
    $(IFS=' '; echo "${default_types[*]}")
Example commit message adding a feature:
   VIS-40908 feat: add .githook to ensure commit messages consistency
"
exit 1

Summary

Git commits and commit messages, act as the backbone for the historical overview of our projects. we need to keep it clean, structured, and informative!

Nobody likes to spend his night reverse-engineering a code change that was made 5 moonlight years ago just to change its behavior.

So please keep it clean, and enforce a level of validation over it! careless people are everywhere.

 
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