Bats Testing Patterns

Bats Testing Patterns

Comprehensive guidance for writing comprehensive unit tests for shell scripts using Bats (Bash Automated Testing System), including test patterns, fixtures, and best practices for production-grade shell testing.

When to Use This Skill

• Writing unit tests for shell scripts
• Implementing test-driven development (TDD) for scripts
• Setting up automated testing in CI/CD pipelines
• Testing edge cases and error conditions
• Validating behavior across different shell environments
• Building maintainable test suites for scripts
• Creating fixtures for complex test scenarios
• Testing multiple shell dialects (bash, sh, dash)

Detailed patterns and worked examples

Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.

Testing Error Conditions

#!/usr/bin/env bats

@test "Function fails with missing file" {
    run my_function "/nonexistent/file.txt"
    [ "$status" -ne 0 ]
    [[ "$output" == *"not found"* ]]
}

@test "Function fails with invalid input" {
    run my_function ""
    [ "$status" -ne 0 ]
}

@test "Function fails with permission denied" {
    touch "$TMPDIR/readonly.txt"
    chmod 000 "$TMPDIR/readonly.txt"
    run my_function "$TMPDIR/readonly.txt"
    [ "$status" -ne 0 ]