git pre-push hook: run test on each new commit

Question

Context

I want to ensure that each commit I push pass tests.

I want to check this on my (client) side, i.e. before commits are even pushed (so I don't want to rely on CI tools).

Problem

Currently, I have implemented a pre-commit hook that run my tests, so that I cannot even commit a broken state.

However, my test suite takes more than a few seconds to run. It is that much time I need to wait prior to writing my commit message. This makes it impractical to use on a daily basis; both because I frequently commit, and that I sometimes purposefully want to commit a broken state to be squashed later (I know about git commit --no-verify, but that is not the point).

Question

So instead of checking each commit one at a time (at creation), I want to batch-test them before pushing.

How to implement a pre-push hook that run my test suite for each new commit to be pushed?

(For the sake of simplicity, say that passing tests means test/run_tests.sh returns 0.)

Answer 1

Thanks to phd's hint (in comments) and a shameless pillage of git's own example, I have drafted the following ./.git/hooks/pre-push hook (that I took care to chmod +x beforehand).

It seems to do the job in vanilla situation, we'll see how it goes over time. Anyway, improvements are welcome!

#!/usr/bin/sh

# An example hook script to verify that each commit that is about to be pushed
# pass the `./run_tests` suite. Called by "git push" after it has checked the
# remote status, but before anything has been pushed.
# If the test suite (and so the script) exits with a non-zero status, nothing
# will be pushed.
#
# In any case, we revert to the pre `$ git push` state.


# Retrieve arguments
remote="$1"
url="$2"

z40=0000000000000000000000000000000000000000 # SHA of a non existing commit


# Save current "git state"
current_branch=$(git rev-parse --abbrev-ref HEAD)

STASH_NAME="pre-push-$(date +%s)"
git stash save -q --keep-index $STASH_NAME


# Do wonders
while read local_ref local_sha remote_ref remote_sha
do
        if [ "$local_sha" = $z40 ]
        then
                # Handle delete
                continue # to the next branch
        elif [ "$remote_sha" = $z40 ]
        then
                # New branch, examine all commits
                range="$local_sha"
        else
                # Update to existing branch, examine new commits
                range="$remote_sha..$local_sha"
        fi

        # Retrieve list of commit in "chronological" order
        commits=$(git rev-list --reverse $range)

        # Loop over each commit
        for commit in $commits
        do
            git checkout $commit

            # Run the tests
            ./test/run_tests.sh

            # Retrieve exit code
            is_test_passed=$?

            # Stop iterating if error
            if [ $is_test_passed -ne 0 ]
            then
                echo -e "Aborting push: Test failed for commit $commit,"\
                  "with following error trace:\n"
                # something like: tail test/run_tests.log
                break 2
            fi
        done
done


# Revert to pre-push state
git checkout $current_branch

STASH_NUM=$(git stash list | grep $STASH_NAME | sed -re 's/stash@\{(.*)\}.*/\1/')
if [ -n "$STASH_NUM" ]
then
    git stash pop -q stash@{$STASH_NUM}
fi
#removed fi

# Return exit code
exit $is_test_passed