Contributing to lplex

Prerequisites

• Go 1.25 or later
• golangci-lint for linting

Build and test

# Build all binaries
go build ./...

# Build specific binaries
go build -o lplex ./cmd/lplex
go build -o lplex-cloud ./cmd/lplex-cloud
go build -o lplexdump ./cmd/lplexdump

# Run all tests
go test ./... -v -count=1

# Lint (must pass before pushing)
golangci-lint run

Code generation

If you modify .pgn DSL files:

go generate ./pgn/...

If you modify .proto files:

# Install protoc plugins if needed
go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

make proto

Code style

• No mocks in tests. Use real instances of brokers, servers, journal writers, etc. Mocks hide bugs; real instances catch them.
• Tests go in mod tests {} at the bottom of the file when colocated with non-test code.
• Modern Go patterns: slog for logging, slices package, enhanced ServeMux routing.
• CAN data follows NMEA 2000 conventions: little-endian, 0xFF padding, fast-packet protocol.
• Sequence numbers start at 1 (0 means "never ACK'd").
• Run golangci-lint run before pushing. CI enforces this.

PGN packet tests

PGN decoders have a table-driven test framework in pgn/packets_test.go. Each entry specifies a PGN number, hex packet data (as output by lplexdump), and the expected decoded struct. The framework verifies both decode and encode round-trip automatically.

To add a test from real device data:

1. Capture a frame: lplexdump -decode -json -pgn <pgn>
2. Copy the data field as hex and the decoded fields as the want struct
3. Append to the packetTests slice in pgn/packets_test.go

See the PGN tutorial for the full walkthrough.

PR workflow

1. Fork and create a feature branch
2. Write code and tests
3. Run go test ./... -v -count=1
4. Run golangci-lint run
5. Open a PR with a clear description of what changed and why

Package layout

Package	Owns
lplex (root)	Broker, Server, Consumer, CANReader, CANWriter, JournalWriter, JournalKeeper, DeviceRegistry, ValueStore, FastPacketAssembler, ReplicationClient, ReplicationServer, InstanceManager, HoleTracker, BlockWriter, EventLog, filters, ring buffer
cmd/lplex/	Boat server binary
cmd/lplex-cloud/	Cloud server binary
cmd/lplexdump/	CLI client binary
cmd/pgngen/	PGN code generator binary
lplexc/	Go client library
canbus/	CAN ID parsing and ISO NAME decoding
journal/	Journal format types and reader
pgn/	Generated PGN types, decoders, and Registry (with metadata: fast-packet, interval, on-demand)
pgngen/	DSL parser (PGN-level attributes, enums, lookups, dispatch) and code generators (Go, Protobuf, JSON Schema)
proto/replication/v1/	Protobuf/gRPC definitions

Release process

Tags trigger GoReleaser via GitHub Actions:

git tag -a v0.2.0 -m "v0.2.0"
git push origin v0.2.0

This builds binaries (Linux amd64/arm64), .deb packages, Docker images (ghcr.io/sixfathoms/lplex), and pushes the Homebrew formula to sixfathoms/homebrew-tap.