// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package stats

import (
	"os"
	"runtime"
	"testing"
	"time"
)

// TestMain installs a heap watchdog for the whole package run: the
// review probes include bin-count and quantile cases that can ask for
// tens of gigabytes when a guard regresses, and an editor session was
// already lost to a runaway test allocation once. Any runaway now panics
// and unwinds instead of taking the host with it.
func TestMain(m *testing.M) {
	const cap = 3 << 30 // race instrumentation inflates the heap; a runaway is far above this
	stop := make(chan struct{})
	go func() {
		ticker := time.NewTicker(20 * time.Millisecond)
		defer ticker.Stop()
		for {
			select {
			case <-stop:
				return
			case <-ticker.C:
				var m runtime.MemStats
				runtime.ReadMemStats(&m)
				if m.HeapAlloc > cap {
					panic("stats test binary heap above 3 GiB: an entry point is allocating without bound")
				}
			}
		}
	}()
	code := m.Run()
	close(stop)
	os.Exit(code)
}