pre-commit-checks

#! /bin/bash -u
#
# License: GPLv3 or higher
# XXX: Probably want _some_ output while setting up test environment,
#      but easy_install, pip install and setup.py install/test/develop
#      are all way to verbose, even with --quiet.

flake8="$(git config hooks.flake8 || which flake8 2>/dev/null)"
virtualenv="$(git config hooks.virtualenv || which virtualenv 2>/dev/null)"

FLAKE8_ERROR="Could not find flake8.
Please see README for details, or run:

    pip install flake8

in your development VirtualEnv.
"

VIRTUALENV_ERROR="Could not find virtualenv.
Point hooks.virtualenv to the virtualenv executable, or add it to your
PATH. See README for details.
"

die () {
    [ -n "${1-}" ] && echo "Error: $1"
    exit ${2:-1}
} >&2

debug () {
    echo >&2 "$@"
}

# on_exit / add_on_exit code inspired by:
# http://www.linuxjournal.com/content/use-bash-trap-statement-cleanup-temporary-files
declare -a on_exit_items

quoteargs () {
    local i str='' singlequote="'\''"
    for i; do
        str="$str '${i//\'/$singlequote}'"
    done
    printf %s "${str# }"
}

function on_exit()
{
    for i in "${on_exit_items[@]}"
    do
        eval "$i"
    done
}

function add_on_exit()
{
    local n=${#on_exit_items[*]}
    on_exit_items[$n]="$(quoteargs "$@")"
    if [[ $n -eq 0 ]]; then
        trap on_exit EXIT
    fi
}

### Flake8 checks
# Flake8 (pep8, rather) has a --diff option, but it seems to be flawed
# (did not detect bad indentation, at least). We'll check both HEAD and
# index, and diff the results of those.
# XXX: renames are at the moment treated as all-new material.
flake8_diff () {
    # flake8_diff a b
    # a and b assumed to be directories
    [ -z "${flake8}" ] && {
        # XXX: better way to do this?
        (die "${FLAKE8_ERROR}")
        return $?
    }

    local a="${1%%/}" b="${2%%/}"
    # use cut to trim the directory names (len+2 to get past the slash).
    ! fgrep -xv -f <($flake8 "${a}" | cut -c "$((${#a}+2))-") \
        <($flake8 "${b}" | cut -c "$((${#b}+2))-")
}

### Python testing
# "python setup.py test" is much to verbose about thing not really
# relevant. asd
unittest_discover () {
    ### unittest_discover scratch_dir project_dir
    # initialize virtualenv, easy_install project,
    # run "python -m unittest discover" on project with venv python.
    [ -z "$virtualenv" ] && {
        # XXX: better way to do this?
        (die "${VIRTUALENV_ERROR}")
        return $?
    }

    local scratch="${1%%/}" proj="${2%%/}"
    local venv="${scratch}/venv" log="${scratch}/log"
    debug "Initialize virtualenv"
    $virtualenv "$venv" > /dev/null || {
        (die "Failed to create virtualenv.")
        return $?
    }
    debug "Install project (will probably take some time)"
    "${venv}/bin/easy_install" -Z "${proj}" &> "$log" || {
        cat "$log"
        (die "Test installation failed.")
        return $?
    }
    "${venv}/bin/python" -m unittest discover -v "$proj"
}

if git rev-parse --verify HEAD &>/dev/null
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

exec 1>&2

tmpdir="$(mktemp -d --tmpdir)" || die "Failed to create tempdir?!"
add_on_exit rm -rf "$tmpdir"

mkdir "${tmpdir}/old" "${tmpdir}/new"
git checkout-index -q -a --prefix="${tmpdir}/new/"
git archive $against | tar -C "${tmpdir}/old" -x -f -

flake8_diff "${tmpdir}/old" "${tmpdir}/new"
FLAKE8_STATUS=$?

unittest_discover "$tmpdir" "${tmpdir}/new"
TEST_STATUS=$?

# "git diff --check" is not very clear without color, so force color=auto.
git diff-index --check --cached --color=auto $against

[ $? -eq 0 -a $FLAKE8_STATUS -eq 0 -a $TEST_STATUS -eq 0 ] ||
    die "You've got some issues to deal with."