Go Testable Design

Guide Go development with tests: small behavior first, executable documentation, clear boundaries, diagnostic assertions, and incremental refactoring. Informed by patterns from learn-go-with-tests, a community-maintained guide to TDD in Go.

When to Use

Use this skill when the user asks to:

• Build or change Go code using TDD, tests first, red-green-refactor, or outside-in / acceptance-first starts.
• Add, improve, or explain Go unit or acceptance tests.
• Match acceptance / public-boundary coverage to the repository's existing test harness instead of inventing a new form.
• Design Go code around interfaces, io.Reader/io.Writer, fs.FS, http.Handler, context.Context, goroutines, channels, storage boundaries, or package purity.
• Refactor Go code while preserving behavior.
• Review Go code for testability, missing test cases, or IO creeping into decision packages.
• Learn or demonstrate Go concepts through tests.

Do not use this skill for non-Go projects, generic CI setup, or broad architecture work where tests are not part of the task.

Core Rules