test.sh

#!/usr/bin/env bash

fail() {
    echo "$0: $*"
    exit 1
}

captured_output=/tmp/captured_output
temp_dir=/tmp/test-script-folder
rm -rf $temp_dir
mkdir -p $temp_dir

printf "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n" > $temp_dir/ten_lines
printf "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n0\n" > $temp_dir/eleven_lines

rm_long_files() {
    ls $1
}

rm_long_files $temp_dir > $captured_output || fail "command returned error"

expected="rm $temp_dir/eleven_lines
"
actual=$(cat $captured_output)
[ "$expected" == "$actual" ] || fail "
Expected:
--
$expected
--
Actual:
--
$actual
--
"

echo OK