Testing & linting

$ cat cleanup.sh
#!/usr/bin/env bash
dir=$1
rm -rf $dir/*
for f in $(ls $dir); do echo $f; done
$ shellcheck cleanup.sh

In cleanup.sh line 3:
rm -rf $dir/*
       ^--^ SC2115 (warning): Use "${var:?}" to ensure this never expands to /* .
       ^--^ SC2086 (info): Double quote to prevent globbing and word splitting.

In cleanup.sh line 4:
for f in $(ls $dir); do echo $f; done
         ^-------^ SC2045 (error): Iterating over ls output is fragile. Use globs.

# Word splitting is intended: $EXTRA_OPTS holds several flags.
# shellcheck disable=SC2086
exec myapp $EXTRA_OPTS

$ shfmt -d -i 2 cleanup.sh      # show the diff
$ shfmt -w -i 2 scripts/        # rewrite in place

#!/usr/bin/env bash
# lib/checks.sh
set -euo pipefail

is_port() {                      # is_port 8080 → status 0; is_port abc → status 1
  [[ "$1" =~ ^[0-9]+$ ]] && (( $1 >= 1 && $1 <= 65535 ))
}

main() {
  is_port "${1:-}" || { echo "invalid port: ${1:-}" >&2; exit 2; }
  echo "port $1 ok"
}

# run main only when executed, not when sourced by tests
[[ "${BASH_SOURCE[0]}" == "$0" ]] && main "$@"

#!/usr/bin/env bats
# tests/checks.bats

setup() {
  source "$BATS_TEST_DIRNAME/../lib/checks.sh"
}

@test "accepts a valid port" {
  run is_port 8080
  [ "$status" -eq 0 ]
}

@test "rejects text" {
  run is_port abc
  [ "$status" -ne 0 ]
}

@test "rejects 70000" {
  run is_port 70000
  [ "$status" -ne 0 ]
}

@test "main prints a friendly message" {
  run bash "$BATS_TEST_DIRNAME/../lib/checks.sh" 443
  [ "$status" -eq 0 ]
  [[ "$output" == *"port 443 ok"* ]]
}

$ bats tests/
checks.bats
 ✓ accepts a valid port
 ✓ rejects text
 ✓ rejects 70000
 ✓ main prints a friendly message

4 tests, 0 failures

name: scripts
on: [push, pull_request]
jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: shellcheck -x scripts/*.sh lib/*.sh
      - run: sudo apt-get update && sudo apt-get install -y bats
      - run: bats tests/