Bash and Test-Driven Development

Question

When writing more than a trivial script in bash, I often wonder how to make the code testable.

It is typically hard to write tests for bash code, due to the fact tha

Answer 1

Writing what Meszaros calls consumer tests is hard in any language. Another approach is to verify the behavior of commands such as rsync manually, then write unit tests to prove specific functionality without hitting the network. In this slightly-modified example, $run is used to print the side-effects if the script is run with the keyword "test"

function distribute {
    local file=$1 ; shift
    for host in $@ ; do
        $run rsync -ae ssh $file $host:$file
    done
}

if [[ $1 == "test" ]]; then
    run="echo"
else
    distribute schedule.txt $*
    exit 0
fi

#    
# Built-in self-tests
#

output=$(mktemp)
expected=$(mktemp)
set -e
trap "rm $got $expected" EXIT

distribute schedule.txt login1 login2 > $output
cat << EOF > $expected
rsync -ae ssh schedule.txt login1:schedule.txt
rsync -ae ssh schedule.txt login2:schedule.txt
EOF
diff $output $expected
echo -n '.'

echo; echo "PASS"