golang-spf13-cobra

What problem does it solve?

It helps you design and implement correct, maintainable Go CLI command trees using spf13/cobra, including reliable error propagation, argument validation, flag behavior, and shell completions.

Core Features & Use Cases

• Command lifecycle correctness: Use the proper Run* hooks (especially RunE) and place initialization in PersistentPreRunE.
• Robust argument validation: Validate positional args with cobra’s Args validators instead of manual checks inside RunE.
• Predictable, testable output: Write to cmd.OutOrStdout() / cmd.ErrOrStderr() so command behavior is unit-test friendly.
• Ergonomic flags and constraints: Apply required/optional flag rules with MarkFlagRequired, MarkFlagsMutuallyExclusive, MarkFlagsOneRequired, MarkFlagsRequiredTogether, and Changed().
• Shell completions & docs: Add static/dynamic completions (ValidArgs, ValidArgsFunction, RegisterFlagCompletionFunc) and generate documentation/man pages from the command tree.
• Testing patterns that avoid state leaks: Recreate a fresh command tree per test and verify behavior through captured output.

Quick Start

Use the skill to implement a cobra root command with subcommands, set SilenceUsage and SilenceErrors, validate args via the Args field, return errors from RunE, and write all output through cmd.OutOrStdout() / cmd.ErrOrStderr().