awesome-ai-rules copilot-instructions.md

GitHub Copilot Instructions: Go

Inline Completion Priorities

• Suggest idiomatic Go first, clever abstractions second.
• Default to explicit error checks with immediate returns.
• Prefer readable control flow over compressed one-liners.
• Keep generated snippets aligned with existing package style.

Go API Conventions

• Package names: short, lowercase, no underscores.
• Export only what callers need; keep helpers unexported.
• Favor composition via struct fields over inheritance-style hierarchies.
• Avoid init() unless a framework requires automatic registration.

Interfaces

• Prefer small interfaces focused on behavior.
• Accept interfaces in inputs where mocking/substitution is needed.
• Return concrete structs from constructors and factories.
• Avoid generating broad "god interfaces".

Error Patterns

• Use if err != nil { return ... } consistently.
• Wrap with fmt.Errorf("context: %w", err) when propagating.
• Use errors.Is / errors.As for branching logic.
• Do not ignore returned errors from I/O, close, or encode/decode calls.

Concurrency

• Include context.Context as first argument for cancellable work.
• Suggest goroutines only with clear synchronization (WaitGroup, channels, errgroup).
• Avoid channel misuse: sender closes, receiver ranges.
• Prefer race-safe patterns and recommend go test -race when relevant.

Testing

• Generate table-driven tests for function matrices.
• Use subtests for each table row with descriptive names.
• Prefer testify/require for setup-critical assertions.
• Keep fixtures lightweight and deterministic.

Tooling Awareness

• Assume gofmt/goimports will run; produce format-stable code.
• Keep code compatible with golangci-lint defaults.
• Favor stdlib dependencies unless a third-party package is clearly justified.
• Keep module imports tidy and consistent with go.mod.