A tool to "bisect" Node modules, useful to find out which module is causing failures

bisect-node-modules

#!/bin/sh
set -e

# A tool to "bisect" Node modules, useful to find out which module is causing
# failures.
#
# Given a `node_modules` list known to work and one which is known to be broken,
# do the following:
#
#   mkdir /tmp/base_dir
#
# Copy the working modules:
#   cp -a node_modules /tmp/base_dir/ok
#
# Copy the bad modules:
#   cp -a node_modules /tmp/base_dir/bad
#
# Create a modules.lst with the following content:
#
#  O module1
#  O module2
#  O module3
#  O module4
#
# Run `bisect-modules /tmp/base_dir`: it will copy all modules from
# /tmp/base_dir/ok in node_modules
#
# Edit modules.lst, replace the O in the first column with B (or anything else)
# and run `bisect-modules /tmp/base_dir` again to replace the modules marked B
# with modules from /tmp/base_dir/bad. Try variations of B and O to find out
# which module is causing the failure.
modules_base_dir=$1

cat modules.lst | while read ok name ; do
    if [ "$ok" = "O" ] ; then
        subdir="ok"
    else
        subdir="bad"
    fi
    rm -rf node_modules/$name
    echo cp -a $modules_base_dir/$subdir/$name node_modules
    cp -a $modules_base_dir/$subdir/$name node_modules
done