// Package testlog silences slog in test binaries.
//
// The hold, PDS and appview packages log at INFO while they boot, subscribe,
// and tear down, and every test that starts one of them produces dozens of
// lines. `go test` only prints a package's output when it fails, so the noise
// lands exactly where the failure message is, and buries it.
//
// Call Quiet from a package's TestMain. Logs come back with `go test -v` or
// ATCR_TEST_LOGS=1, so a failing run can be re-run with them on. Note that
// `go test -json` implies -v, so tooling that streams JSON sees the logs too.
package testlog

import (
	"flag"
	"io"
	"log/slog"
	"os"
	"testing"
)

// Quiet replaces the default slog logger with one that discards everything,
// unless the test binary runs verbose (-v) or ATCR_TEST_LOGS is set. It parses
// the test flags if that has not happened yet, which TestMain otherwise leaves
// to m.Run.
func Quiet() {
	if !flag.Parsed() {
		flag.Parse()
	}
	if testing.Verbose() || os.Getenv("ATCR_TEST_LOGS") != "" {
		return
	}
	slog.SetDefault(slog.New(slog.NewTextHandler(io.Discard, nil)))
}