Easy nocheckin with git

Sometimes, you want to add some code to test something out, but you definitely want to make sure you don’t git commit it. Of course, you should always check the output of git diff before you make a commit (you do, right?), but if you have a lot of changes things can slip through the cracks.

A solution is to write a comment containing a string such as “nocheckin”:

function do_stuff() {
    printf("hello!!! testing!!!\n"); // nocheckin
    call_important_thing();
    call_other_thing();
}

Then, you need to set git up such that it refuses to make a commit if it detects the “nocheckin” string anywhere in your changed files. Here’s how to do it.

Save this script somewhere — I put it in ~/.bin/validate-nocheckin:

#!/bin/sh -eu

# get the staged files
s_files=$(git diff --name-only --cached)

# if a staged file contains the keyword, fail the commit
for s_file in ${s_files};do
    if grep -q -E 'nocheckin' ${s_file};then
        echo "ERROR: ${s_file} contains 'nocheckin', failing commit"
        exit 1
    fi
done

exit 0

Then, whenever you want this feature, simply symlink that script as the pre-commit hook by running this from the root folder of your git repository:

ln -s ~/.bin/validate-nocheckin .git/hooks/pre-commit

If you then try to commit your code, it won’t work:

vladh ki test:master $ git commit -m 'will it work?'
ERROR: main.c contains 'nocheckin', failing commit