go install github.com/alesr/lacune@latest- visualize inline code coverage
- re-run tests on demand
- scroll through and search code
- measure GC behavior of your test suite (wall time + gctrace telemetry)
demo.mp4
Run lacune in the root directory of your Go project (where your go.mod file is located). It will automatically detect your test files and coverage profiles.
Press b in the TUI to open the GC report overlay. Lacune runs your project's test suite (go test ./...) under whatever garbage collector is the default for your Go toolchain, then shows how your code behaves under that GC.
Go version (from go.mod) |
Default GC |
|---|---|
| 1.25 and earlier | Classic GC |
| 1.26+ | Green Tea GC |
The report measures:
- Wall time — how long the full test run took
- GC cycles — number of GC events during the run
- Total GC pause — sum of stop-the-world pause time
- GC CPU — share of CPU spent in GC
- Peak heap — largest heap size observed during a GC cycle
Telemetry comes from GODEBUG=gctrace=1. A compile-only warm-up pass runs first so wall time reflects test execution, not compilation.
Contributions are welcome! Open an issue or submit a PR.