lklimek/go-best-practices

Go Best Practices

Technical Standards

• Go Version: 1.21+ (or latest stable)
• Code Style: gofmt/goimports enforced
• Linting: golangci-lint with comprehensive checks
• Testing: go test with table-driven tests
• Documentation: One-line Godoc comment for every exported identifier; expand only when non-obvious
• Error Handling: Explicit with error wrapping (fmt.Errorf with %w)
• Modules: Go modules for dependency management
• Context: context.Context for cancellation and timeouts

Best Practices

• Accept interfaces, return structs
• Keep interfaces small (single-method often best)
• Use context.Context for cancellation propagation
• Always check errors — don't ignore with _
• Use defer for cleanup (close files, unlock mutexes)
• Goroutines: always know when they exit
• Channels for communication, mutexes for state
• Prefer composition over embedding
• Use internal/ package for private code
• Prefer standard library first

Common Patterns

• Error Wrapping: fmt.Errorf("context: %w", err)
• Options Pattern: Functional options for constructors
• Context: Pass as first parameter
• Interfaces: io.Reader, io.Writer, io.Closer patterns
• Middleware: Handler wrapping for HTTP servers
• Worker Pools: Channel-based task distribution
• Graceful Shutdown: Signal handling with context cancellation

Concurrency

• Always handle goroutine lifecycle — know when they exit
• Use context for cancellation propagation
• Protect shared state with mutexes or channels
• Use sync.WaitGroup to wait for goroutines
• Use buffered channels carefully — understand blocking
• Use select for channel multiplexing
• Implement worker pools for bounded concurrency

Error Handling

• Wrap errors with context: fmt.Errorf("failed to read: %w", err)
• Define custom error types for sentinel errors
• Use errors.Is() and errors.As() for checking
• Return errors as last return value
• Don't panic in library code — return errors
• Log errors at the right level in the call stack

Code Quality Tools

• Formatting: gofmt, goimports
• Linting: golangci-lint (staticcheck, errcheck, govet, etc.)
• Testing: go test -race -cover ./...
• Security: gosec
• Dependencies: go mod tidy, go mod verify
• Benchmarks: go test -bench=. -benchmem

Common Pitfalls

• Don't ignore errors
• Don't use goroutines without understanding their lifecycle
• Don't use global variables excessively
• Don't use init() unless absolutely necessary
• Don't over-use interfaces early — add when needed
• Don't forget to close resources (files, connections)
• Don't use panic/recover for normal error handling

Code Review Checklist

• Idiomatic Go style (Effective Go compliance)
• Error handling: explicit checks, no ignored errors, proper wrapping with %w
• Goroutine lifecycle: clear start/stop, no leaks
• Interface design: small, focused, used appropriately
• Context propagation for cancellation
• Defer usage for cleanup
• DRY compliance: duplicated logic, copy-paste patterns
• Naming clarity: exported vs unexported, package naming
• Test quality: table-driven tests, meaningful assertions, race condition coverage
• Code brevity: flag code that can be expressed in fewer lines without losing clarity

Use GO-NNN prefix for all findings.