plumb

Better code coverage for Go.

plumb renders Go coverage profiles into a modern HTML report — the Istanbul of the Go world.

go tool cover -html works but looks like 2013. No dark mode, no file tree, no search, no function coverage. plumb fixes that.

⚠️ Status: pre-alpha. APIs and flags will change. If something breaks, please open an issue.

Install

go install github.com/z3le/plumb/cmd/plumb@latest

Requires Go 1.21+.

Usage

Run your tests as normal, then pass the profile to plumb:

go test -coverprofile=coverage.out ./...
plumb report coverage.out --open

The --open flag opens the report in your browser automatically.

Flags

plumb report [flags] [profile]

  --open         open report in browser after writing
  --out file     output HTML file (default: coverage.html)
  --title str    report title (default: module name)

What the report shows

• File list sortable by statement %, function %, or name
• Line-by-line source view with green/red coverage highlighting
• Hit counts per line
• Per-function call counts with ×N badges
• Summary bar: Statements % and Functions %
• Dark mode via prefers-color-scheme
• Single self-contained HTML file — no external requests

How does the report look like

Roadmap

• plumb run — thin wrapper around go test -coverpkg=./... -coverprofile=...
• Diff coverage — show coverage only on lines changed since a git ref
• Branch coverage — AST-based approximation
• plumb check — CI threshold enforcement

License

MIT