Building a CLI Application

🎓 TUTORIAL | Complete example of testing a CLI application

Complete example of testing a CLI application with Chicago TDD Tools.

Project Structure

myapp/
├── src/
│   ├── main.rs         # CLI entry point
│   └── commands/
│       ├── list.rs     # List command
│       ├── add.rs      # Add command
│       └── delete.rs   # Delete command
└── tests/
    ├── cli_tests.rs    # CLI integration tests
    └── commands_tests.rs

Testing CLI Commands

Example: List Command Test

#![allow(unused)]
fn main() {
test!(test_list_command, {
    let output = CliTest::new("myapp", vec!["list"])
        .run()?;

    assert!(output.contains("Item"));
    assert!(output.exit_code == 0);
});
}

Example: Add Command Test

#![allow(unused)]
fn main() {
test!(test_add_command, {
    let output = CliTest::new("myapp", vec![
        "add",
        "--name", "New Item",
        "--priority", "high"
    ]).run()?;

    assert!(output.contains("Added"));
    assert!(output.exit_code == 0);
});
}

Example: Error Handling

#![allow(unused)]
fn main() {
test!(test_invalid_command, {
    let result = CliTest::new("myapp", vec!["invalid"])
        .run();

    assert!(result.is_err());
});
}

Best Practices for CLI Testing

✅ Do:

• Test all commands
• Test argument combinations
• Test error cases
• Use snapshots for complex output
• Test environment variables

❌ Don't:

• Hard-code full output
• Test shell integration
• Test external tools

See: CLI Testing

Next Steps

Learn more:

• CLI Testing Guide - Deep dive into trycmd patterns
• Best Practices - CLI testing best practices
• Web Service Testing - Compare with testing web services

Ready to test?

• Set up a new project with Chicago TDD Tools
• Start with a simple command
• Add tests as you build features