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Testing & coverage

The module is tested to 100% statement coverage, including every error branch, and the coverage gate is enforced in CI.

COVERPKG=$(go list ./... | paste -sd, -)
go test -race -coverpkg="$COVERPKG" -coverprofile=cover.out ./...
go tool cover -func=cover.out | tail -1   # 100.0%

The hermetic round-trip

cmd/fake-lsp is a deterministic LSP-like subprocess: it reads Content-Length -framed JSON-RPC on stdin and writes canned responses on stdout (initialize, completion, hover, definition, and a didOpen → publishDiagnostics notification). The integration test builds it, points LSPBRIDGE_FAKE at it, and drives a real WebSocket through HandleWS the way a CodeMirror SPA would — exercising the whole WS → subprocess → WS path without depending on texlab/gopls/etc. being installed.

Reaching the error branches

The otherwise-unreachable failure paths are covered with small seams:

  • Framing pumps are extracted as standalone functions over an io.Reader / io.Writer and a narrow WS interface, so an in-memory fake can force framing errors, short bodies, and write failures on demand.
  • Pipe/spawn failures (StdinPipe, StdoutPipe, Start) are injected via method-value seams to confirm the bridge emits the right JSON-RPC error frame.
  • Concurrency caps are unit-tested directly (global saturation, per-user ceiling, and the release path that deletes the counter at zero).

Six arches, gated exec

CI builds and tests on all six 64-bit Go targets: amd64 and arm64 run natively (the full round-trip runs there), while riscv64, loong64, ppc64le and s390x run under qemu-user.

A host-built fake-lsp can't be exec'd for a foreign arch under qemu-user, and there's no real loopback net, so the qemu lanes set LSPBRIDGE_NO_EXEC=1, which skips the exec/WebSocket tests. The pure framing, registry and concurrency logic still runs on every arch — so the cross-arch lanes validate the portable core, and the native ubuntu/macos lane enforces the 100% gate over the whole suite.