Shell Script Quality

Shell Script Quality

Comprehensive shell script linting and testing using ShellCheck and BATS with 2025 best practices.

Quick Start

Copy this workflow checklist and track your progress:

Shell Script Quality Workflow:
- [ ] Step 1: Lint with ShellCheck
- [ ] Step 2: Fix reported issues
- [ ] Step 3: Write BATS tests
- [ ] Step 4: Verify tests pass
- [ ] Step 5: Integrate into CI/CD

Core Workflow

Step 1: Lint with ShellCheck

# Lint single file
shellcheck script.sh

# Lint all scripts
find scripts -name "*.sh" -exec shellcheck {} +

# Use config file if present
shellcheck -x script.sh

Common fixes: See SHELLCHECK.md for fix patterns

Step 2: Fix Reported Issues

Apply fixes for common warnings:

• SC2086: Quote variables: "$var" not $var
• SC2155: Separate declaration and assignment
• SC2181: Check exit code directly with if ! command

For detailed fixes: See SHELLCHECK.md

Step 3: Write BATS Tests

#!/usr/bin/env bats

setup() {
    source "$BATS_TEST_DIRNAME/../scripts/example.sh"
}

@test "function succeeds with valid input" {
    run example_function "test"
    [ "$status" -eq 0 ]
    [ -n "$output" ]
}

@test "function fails with invalid input" {
    run example_function ""
    [ "$status" -ne 0 ]
    [[ "$output" =~ "ERROR" ]]
}

Test patterns: See BATS.md for comprehensive testing guide

Step 4: Run Tests

# Run all tests
bats tests/

# Run with verbose output
bats -t tests/

# Run specific file
bats tests/example.bats

If tests fail: Review error output, fix issues, re-run validation

Step 5: CI/CD Integration

GitHub Actions: See CI-CD.md for complete workflows

Quick integration:

- name: ShellCheck
  uses: ludeeus/action-shellcheck@master
- name: Run BATS
  run: |
    sudo apt-get install -y bats
    bats tests/

Script Template

Use this template for new scripts:

#!/bin/bash
set -euo pipefail

# Script directory (portable)
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# Error handler
error_exit() {
    echo "ERROR: $1" >&2
    exit "${2:-1}"
}

# Main function
main() {
    [[ $# -lt 1 ]] && {
        echo "Usage: $0 <argument>" >&2
        exit 1
    }

    # Your logic here
}

# Run if executed directly
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    main "$@"
fi

Installation

ShellCheck:

brew install shellcheck         # macOS
sudo apt-get install shellcheck # Linux

BATS:

brew install bats-core          # macOS
sudo apt-get install bats       # Linux

Configuration

.shellcheckrc in project root:

shell=bash
disable=SC1090
enable=all
source-path=SCRIPTDIR

For configuration details: See CONFIG.md

Testing Claude Code Plugins

Test scripts using CLAUDE_PLUGIN_ROOT:

@test "plugin script works" {
    export CLAUDE_PLUGIN_ROOT="$BATS_TEST_DIRNAME/.."
    run bash "$CLAUDE_PLUGIN_ROOT/scripts/search.sh" "query"
    [ "$status" -eq 0 ]
}

Test hooks with JSON:

@test "hook provides suggestions" {
    local input='{"tool":"Edit","params":{"file_path":"test.txt"}}'
    run bash "$HOOK_DIR/pre-edit.sh" <<< "$input"
    [ "$status" -eq 0 ]
    echo "$output" | jq empty
}

More plugin patterns: See PATTERNS.md

Troubleshooting

ShellCheck:

• SC1090 warnings: Add # shellcheck source=path/to/file.sh
• False positives: Use # shellcheck disable=SCxxxx

BATS:

• Tests interfere: Ensure proper teardown() cleanup
• Can't source script: Add main execution guard
• Path issues: Use $BATS_TEST_DIRNAME for relative paths

Detailed troubleshooting: See TROUBLESHOOTING.md

Validation Loop Pattern

For quality-critical operations:

1. Make changes to script
2. Validate immediately: shellcheck script.sh
3. If validation fails:
   • Review error messages carefully
   • Fix the issues
   • Run validation again
4. Only proceed when validation passes
5. Run tests: bats tests/script.bats
6. If tests fail, return to step 1

Reference Files

• SHELLCHECK.md - Complete ShellCheck guide and fix patterns
• BATS.md - BATS testing comprehensive guide
• CI-CD.md - GitHub Actions, GitLab CI, pre-commit hooks
• PATTERNS.md - Common patterns and examples
• CONFIG.md - Configuration and setup details
• TROUBLESHOOTING.md - Common issues and solutions

Quick Quality Check

Run this command for complete validation:

# Check everything
find scripts -name "*.sh" -exec shellcheck {} + && bats tests/

# Or use quality check script
bash scripts/check-quality.sh