Bash script to calculate (jest) test coverage diff

coverage-diff.sh

#!/bin/bash

# Output sample
# ========================= Total coverage diff summary ==========================
# lines        : +0.46% ( +33 )
# statements   : +0.49% ( +36 )
# functions    : +0.66% ( +17 )
# branches     : +0.16% ( +4 )
# ================================================================================

usage() {
	echo "
Usage: coverage-diff [-h?] BRANCH1 [BRANCH2]
Script calculate test coverage diff between two branches.
options:
 -h -?	Print this message and exit"
}

shortusage() {
	echo "
Usage: coverage-diff [-h?] BRANCH1 [BRANCH2]
See coverage-diff -h for help"
}

error() {
	if [[ -n $1 ]];
	then
		echo "\nERROR: $1"
		if [[ -n $2 ]];
		then
			shortusage
		fi
		exit 1
	fi	
}

# Parsing flags
while getopts "h?l:" opt
do
	case $opt in
		h|\?)
			usage
			exit 0
			;;
	esac
done

CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
BRANCH1=$1

if [[ -z $BRANCH1 ]]; then
  error "You must specify at least one branch name!"
fi

BRANCH2=$2

if [[ -z $BRANCH2 ]]; then
  BRANCH2=$CURRENT_BRANCH
fi

if [[ $BRANCH1 == $BRANCH2 ]]; then
  error "Nothing to compare. Either specify BRANCH2 or switch to it first"
fi

# echo "Gathering coverage for '$BRANCH1'…";
git switch --quiet $BRANCH1
npx jest --silent --no-cache --coverage --coverageReporters=json-summary --coverageDirectory="/tmp/$BRANCH1" > /dev/null 2>&1

# echo "Gathering coverage for '$BRANCH2'…";
git switch --quiet $BRANCH2
npx jest --silent --no-cache --coverage --coverageReporters=json-summary --coverageDirectory="/tmp/$BRANCH2" > /dev/null 2>&1


diff() {
  printf "%-13s: %+5.2f%% ( %+d )\n" $1 $(jq "\$b1[0].total.$1.pct-.total.$1.pct" --slurpfile b1 /tmp/$BRANCH2/coverage-summary.json /tmp/$BRANCH1/coverage-summary.json)  $(jq "\$b1[0].total.$1.covered-.total.$1.covered" --slurpfile b1 /tmp/$BRANCH2/coverage-summary.json /tmp/$BRANCH1/coverage-summary.json)
}

echo "========================= Total coverage diff summary =========================="
diff "lines"
diff "statements"
diff "functions"
diff "branches"
echo "================================================================================"

# echo "Cleaning up…"
rm -rf /tmp/{$BRANCH1,$BRANCH2}

# echo "Switching back to $CURRENT_BRANCH"
git switch --quiet $CURRENT_BRANCH