How to handle hook with output on error

[avudnez]

Hi,

Many of my (script) hooks output some text to identify why they failed.
It does not seem very well handled by lefthook, did I miss something ?

The output looks like

lefthook run pre-commit
sync hooks: ✔️ (pre-commit, pre-push)
this is some error message output by first hook

exit status 2this is some error message output by second hook
another line by second hook

exit status 2
  ────────────────────────────────────
summary: (done in 1.15 seconds)

I'd like to be sure that their outputs are correctly concatenated, and not interleaved with exit status n. An indication of which hook output is shown would also be great.

I have seen https://github.com/evilmartians/lefthook/blob/master/docs/configuration.md#fail_text but this is obviously not enough when the script has things to say.

[mrexox]

Hey! Could you please provide the script you use, so I could experiment a bit and provide a working config example?

[avudnez]

Sure thing, here is an example.
It's checking for the string %NOCOMMIT% inside staged files.
I don't mind having to change the output stream used if needed for example.

#!/usr/bin/env bash

## 	Check for %NOCOMMIT% tag inside the diff
##  ----------------------------------------

if git rev-parse --verify HEAD >/dev/null 2>&1
then
	against=HEAD
else
	# Initial commit: diff against an empty tree object
	against=$(git hash-object -t tree /dev/null)
fi

# Redirect output to stderr.
exec 1>&2

## 	Helpers
##  -------

HOOK_EXITCODE=0

function die()
{
	>&2 echo " (!!) ERROR: $*"
	HOOK_EXITCODE=2
}

function diff-lines()
{
    local path=
    local line=
    while read; do
        esc=$'\033'
        if [[ $REPLY =~ ---\ (a/)?.* ]]; then
            continue
        elif [[ $REPLY =~ \+\+\+\ (b/)?([^[:blank:]$esc]+).* ]]; then
            path=${BASH_REMATCH[2]}
        elif [[ $REPLY =~ @@\ -[0-9]+(,[0-9]+)?\ \+([0-9]+)(,[0-9]+)?\ @@.* ]]; then
            line=${BASH_REMATCH[2]}
        elif [[ $REPLY =~ ^($esc\[[0-9;]+m)*\+ ]]; then
            echo "$path:$line:$REPLY"
            if [[ ${BASH_REMATCH[2]} != - ]]; then
                ((line++))
            fi
        fi
    done
}

# Print the offending lines and fail if %NOCOMMIT% tags are present
if git diff --cached $against | diff-lines | grep --color=auto '%NOCOMMIT%'; then
	die "Found %NOCOMMIT% tag(s)"
fi

## 	Finally return an exit code indicating whether any check failed or not
##  ----------------------------------------------------------------------

if [ $HOOK_EXITCODE -ne 0 ]; then
	exit $HOOK_EXITCODE
fi

[avudnez]

Hi @mrexox, have you had a chance to look at this ?