//go:build linux
// +build linux

package staros

import (
	"testing"
	"time"
)

func TestCPUUsageOverDurationGuardsZeroOrNegativeWindow(t *testing.T) {
	if got := cpuUsageOverDuration(10, 0); got != 0 {
		t.Fatalf("expected zero-window cpu usage to clamp to 0, got %v", got)
	}
	if got := cpuUsageOverDuration(10, -time.Millisecond); got != 0 {
		t.Fatalf("expected negative-window cpu usage to clamp to 0, got %v", got)
	}
	if got := cpuUsageOverDuration(-1, time.Second); got != 0 {
		t.Fatalf("expected negative delta cpu usage to clamp to 0, got %v", got)
	}
	if got := cpuUsageOverDuration(0.5, time.Second); got != 50 {
		t.Fatalf("expected normal cpu usage calculation, got %v", got)
	}
}

func TestCPUUsagePercentGuardsInvalidSamples(t *testing.T) {
	if got := cpuUsagePercent(1, 0); got != 0 {
		t.Fatalf("expected zero total ticks to clamp to 0, got %v", got)
	}
	if got := cpuUsagePercent(-1, 4); got != 0 {
		t.Fatalf("expected negative busy ticks to clamp to 0, got %v", got)
	}
	if got := cpuUsagePercent(1, 4); got != 25 {
		t.Fatalf("expected normal cpu percent calculation, got %v", got)
	}
}