react native pre-push hook

#!/bin/sh

## React Native pre-push hook
## --------------------------
## Requires:
##  - concurrently from npm
##  - assumes you have test:ios and test:android tasks setup for any native unit tests

remote="$1"
url="$2"

z40=0000000000000000000000000000000000000000

if [ "$SKIP_CHECKS" = "true" ]
then
	exit 0
fi

if [ -z "$COMPARE_SHA" ]
then
	COMPARE_SHA=master
fi

# https://stackoverflow.com/questions/1527049/join-elements-of-an-array
function join { local d=$1; shift; echo -n "$1"; shift; printf "%s" "${@/#/$d}"; }

while read local_ref local_sha remote_ref remote_sha
do
	if [ "$local_sha" = $z40 ]
	then
		# Handle delete
		:
	else
		declare -a CHECK_CMDS
		if [ "$(git diff $COMPARE_SHA -- src)" != "" ]
		then
			echo "JS changed..."
			CHECK_CMDS+=("flow" "yarn run lint" "jest --silent --coverage --bail")
		fi
		if [ "$(git diff $COMPARE_SHA -- ios)" != "" ]
		then
			echo "iOS changed..."
			CHECK_CMDS+=("yarn run test:ios")
		fi
		if [ "$(git diff $COMPARE_SHA -- android)" != "" ]
		then
			echo "Android changed..."
			CHECK_CMDS+=("yarn run test:android")
		fi
		cmdstr=$(printf '"%s" ' "${CHECK_CMDS[@]}")
		eval concurrently --kill-others-on-fail $cmdstr
		if [ $? -ne 0 ]; then
			exit 1
		fi
	fi
done

exit 0