mk6i-open-oscar-server/state/session_test.go

package state

import (
	"context"
	"fmt"
	"math"
	"net/netip"
	"sync"
	"testing"
	"testing/synctest"
	"time"

	"github.com/mk6i/open-oscar-server/wire"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestSession_UsesFeedbag(t *testing.T) {
	s := NewSession()

	if s.UsesFeedbag() {
		t.Fatalf("UsesFeedbag() = true; want false")
	}

	s.SetUsesFeedbag()

	if !s.UsesFeedbag() {
		t.Fatalf("UsesFeedbag() = false; want true")
	}

	// idempotent
	s.SetUsesFeedbag()
	if !s.UsesFeedbag() {
		t.Fatalf("UsesFeedbag() = false after second SetUsesFeedbag; want true")
	}
}

func TestSessionInstance_NotifyTxn(t *testing.T) {
	alice := NewIdentScreenName("Alice")
	bob := NewIdentScreenName("Bob")

	t.Run("lifecycle", func(t *testing.T) {
		inst := NewSession().AddInstance()
		inst.BeginNotifyTxn()
		assert.True(t, inst.InNotifyTxn())

		require.NoError(t, inst.NotifyTxn(alice, bob))
		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.True(t, shouldNotify)
		assert.ElementsMatch(t, []IdentScreenName{alice, bob}, screenNames)
		assert.False(t, inst.InNotifyTxn())

		shouldNotify, screenNames = inst.EndNotifyTxn()
		assert.False(t, shouldNotify)
		assert.Nil(t, screenNames)
	})

	t.Run("clear on begin", func(t *testing.T) {
		inst := NewSession().AddInstance()
		inst.BeginNotifyTxn()
		require.NoError(t, inst.NotifyTxn(alice))
		inst.BeginNotifyTxn()

		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.False(t, shouldNotify)
		assert.Empty(t, screenNames)
	})

	t.Run("notify without names", func(t *testing.T) {
		inst := NewSession().AddInstance()
		inst.BeginNotifyTxn()
		require.NoError(t, inst.NotifyTxn())

		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.True(t, shouldNotify)
		assert.Empty(t, screenNames)
	})

	t.Run("inactive notify", func(t *testing.T) {
		inst := NewSession().AddInstance()
		assert.ErrorIs(t, inst.NotifyTxn(alice), errNotifyTxnNotActive)

		inst.BeginNotifyTxn()
		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.False(t, shouldNotify)
		assert.Empty(t, screenNames)
	})

	t.Run("dedup", func(t *testing.T) {
		inst := NewSession().AddInstance()
		inst.BeginNotifyTxn()
		require.NoError(t, inst.NotifyTxn(alice, alice))

		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.True(t, shouldNotify)
		assert.Equal(t, []IdentScreenName{alice}, screenNames)
	})

	t.Run("exceeds max names", func(t *testing.T) {
		inst := NewSession().AddInstance()
		inst.BeginNotifyTxn()

		names := make([]IdentScreenName, maxNotifyTxnNames)
		for i := range names {
			names[i] = NewIdentScreenName(fmt.Sprintf("user%d", i))
		}
		require.NoError(t, inst.NotifyTxn(names...))

		shouldNotify, screenNames := inst.EndNotifyTxn()
		assert.True(t, shouldNotify)
		assert.Len(t, screenNames, maxNotifyTxnNames)

		inst.BeginNotifyTxn()
		require.NoError(t, inst.NotifyTxn(names...))
		assert.ErrorIs(t, inst.NotifyTxn(NewIdentScreenName("overflow")), errNotifyTxnTooManyNames)
	})
}

func TestSession_IncrementAndGetWarning(t *testing.T) {
	s := NewSession().AddInstance()

	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		s.Session().ScaleWarningAndRateLimit(1, 1)
		s.Session().ScaleWarningAndRateLimit(2, 1)
		s.Session().ScaleWarningAndRateLimit(3, 1)
	}()

	assert.Equal(t, uint16(1), <-s.WarningCh())
	assert.Equal(t, uint16(3), <-s.WarningCh())
	assert.Equal(t, uint16(6), <-s.WarningCh())

	wg.Wait()
}

func TestSession_SetAndGetInvisible(t *testing.T) {
	s := NewSession().AddInstance()
	assert.False(t, s.Invisible())
	s.SetUserStatusBitmask(wire.OServiceUserStatusInvisible)
	assert.True(t, s.Invisible())
}

func TestSession_SetAndGetScreenName(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Empty(t, s.IdentScreenName())
	sn := NewIdentScreenName("user-screen-name")
	s.Session().SetIdentScreenName(sn)
	assert.Equal(t, sn, s.IdentScreenName())
}

func TestSession_SetAndGetChatRoomCookie(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Empty(t, s.ChatRoomCookie())
	sn := "the-chat-cookie"
	s.Session().SetChatRoomCookie(sn)
	assert.Equal(t, sn, s.ChatRoomCookie())
}

func TestSession_SetAndGetUIN(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Empty(t, s.UIN())
	uin := uint32(100003)
	s.Session().SetUIN(uin)
	assert.Equal(t, uin, s.UIN())
}

func TestSession_SetAndGetClientID(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Empty(t, s.ClientID())
	clientID := "AIM Client ID"
	s.SetClientID(clientID)
	assert.Equal(t, clientID, s.ClientID())
}

func TestSession_SetAndGetKerberosAuth(t *testing.T) {
	s := NewSession().AddInstance()
	assert.False(t, s.KerberosAuth())

	s.SetKerberosAuth(true)
	assert.True(t, s.KerberosAuth())

	s.SetKerberosAuth(false)
	assert.False(t, s.KerberosAuth())
}

func TestSession_SetAndGetRemoteAddr(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Empty(t, s.RemoteAddr())
	remoteAddr, _ := netip.ParseAddrPort("1.2.3.4:1234")
	s.SetRemoteAddr(&remoteAddr)
	assert.Equal(t, &remoteAddr, s.RemoteAddr())
}

func TestSession_TLVUserInfo(t *testing.T) {
	tests := []struct {
		name           string
		givenSessionFn func() *SessionInstance
		want           wire.TLVUserInfo
	}{
		{
			name: "user is active and visible",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.Session().SetIdentScreenName(NewIdentScreenName("xXAIMUSERXx"))
				s.Session().SetDisplayScreenName("xXAIMUSERXx")
				s.Session().ScaleWarningAndRateLimit(10, 1)
				s.SetUserInfoFlag(wire.OServiceUserFlagOSCARFree)
				return s
			},
			want: wire.TLVUserInfo{
				ScreenName:   "xXAIMUSERXx",
				WarningLevel: 10,
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user is on ICQ",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.Session().SetIdentScreenName(NewIdentScreenName("1000003"))
				s.Session().SetDisplayScreenName("1000003")
				s.SetUserInfoFlag(wire.OServiceUserFlagICQ)

				return s
			},
			want: wire.TLVUserInfo{
				ScreenName: "1000003",
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, wire.OServiceUserFlagOSCARFree|wire.OServiceUserFlagICQ),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoICQDC, wire.ICQDCInfo{}),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user is on ICQ with direct connect info from client",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.Session().SetIdentScreenName(NewIdentScreenName("1000003"))
				s.Session().SetDisplayScreenName("1000003")
				s.SetUserInfoFlag(wire.OServiceUserFlagICQ)
				s.SetICQDCInfo(wire.ICQDCInfo{
					DCType:       4,
					ProtoVersion: 10,
				})
				return s
			},
			want: wire.TLVUserInfo{
				ScreenName: "1000003",
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, wire.OServiceUserFlagOSCARFree|wire.OServiceUserFlagICQ),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoICQDC, wire.ICQDCInfo{
							DCType:       4,
							ProtoVersion: 10,
						}),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user has away message set - all instances away",
			givenSessionFn: func() *SessionInstance {
				sg := NewSession()
				s := sg.AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// Add a second instance that is also away
				s2 := sg.AddInstance()
				s2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x30)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user has one instance away, one not away - away flag not set",
			givenSessionFn: func() *SessionInstance {
				sg := NewSession()
				// Create the NOT away instance first so it's used as the base
				s2 := sg.AddInstance()
				s2.Session().SetSignonTime(time.Unix(1, 0))
				// s2 is NOT away - it has default flags only (OServiceUserFlagOSCARFree)
				// Now create the away instance
				s := sg.AddInstance()
				s.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// Since s2 is the first instance and is not away, and allAway() returns false,
				// the unavailable flag should not be set
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x10)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user has two instances away, second goes off away - away flag not set",
			givenSessionFn: func() *SessionInstance {
				sg := NewSession()
				sg.SetSignonTime(time.Unix(1, 0))
				// Set the first instance as away
				s1 := sg.AddInstance()
				s1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// Set the second instance as away
				s2 := sg.AddInstance()
				s2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// Make the second instance as not away
				s2.ClearUserInfoFlag(wire.OServiceUserFlagUnavailable)
				return s1
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x10)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user is invisible",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.SetUserStatusBitmask(wire.OServiceUserStatusInvisible)
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0100)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user is idle",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				// sign on at t=0m
				timeBegin := time.Unix(0, 0)
				s.Session().SetSignonTime(timeBegin)
				// set idle for 1m at t=+5m (ergo user idled @ t=+4m)
				timeIdle := timeBegin.Add(5 * time.Minute)
				s.Session().SetNowFn(func() time.Time { return timeIdle })
				s.SetIdle(1 * time.Minute)
				// now it's t=+10m, ergo idle time should be t10-t4=6m
				timeNow := timeBegin.Add(10 * time.Minute)
				s.Session().SetNowFn(func() time.Time { return timeNow })
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(0)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoIdleTime, uint16(6)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user goes idle then returns",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.SetIdle(1 * time.Second)
				s.UnsetIdle()
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user has capabilities",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				s.SetCaps([][16]byte{
					{
						// chat: "748F2420-6287-11D1-8222-444553540000"
						0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1,
						0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00,
					},
					{
						// chat2: "748F2420-6287-11D1-8222-444553540000"
						0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1,
						0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01,
					},
				})
				return s
			},
			want: wire.TLVUserInfo{
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoOscarCaps, []byte{
							// chat: "748F2420-6287-11D1-8222-444553540000"
							0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1,
							0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00,
							// chat: "748F2420-6287-11D1-8222-444553540000"
							0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1,
							0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01,
						}),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
		{
			name: "user has buddy icon",
			givenSessionFn: func() *SessionInstance {
				s := NewSession().AddInstance()
				s.Session().SetSignonTime(time.Unix(1, 0))
				return s
			},
			want: wire.TLVUserInfo{
				WarningLevel: 0,
				TLVBlock: wire.TLVBlock{
					TLVList: wire.TLVList{
						wire.NewTLVBE(wire.OServiceUserInfoSignonTOD, uint32(1)),
						wire.NewTLVBE(wire.OServiceUserInfoUserFlags, uint16(0x0010)),
						wire.NewTLVBE(wire.OServiceUserInfoStatus, uint32(0x0000)),
						wire.NewTLVBE(wire.OServiceUserInfoMySubscriptions, uint32(0)),
					},
				},
			},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			s := tt.givenSessionFn()
			assert.Equal(t, tt.want, s.Session().TLVUserInfo())
		})
	}
}

func TestSession_SendAndRecvMessage_ExpectSessSendOK(t *testing.T) {
	s := NewSession().AddInstance()
	s.SetSignonComplete()

	msg := wire.SNACMessage{
		Frame: wire.SNACFrame{
			FoodGroup: wire.ICBM,
		},
	}

	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer s.CloseInstance()
		status := s.RelayMessageToInstance(msg)
		assert.Equal(t, SessSendOK, status)
	}()

loop:
	for {
		select {
		case m := <-s.ReceiveMessage():
			assert.Equal(t, msg, m)
		case <-s.Closed():
			break loop
		}
	}

	wg.Wait()
}

func TestSession_SendMessage_SessSendClosed(t *testing.T) {
	s := NewSession().AddInstance()
	s.CloseInstance()
	if res := s.RelayMessageToInstance(wire.SNACMessage{}); res != SessSendClosed {
		t.Fatalf("expected SessSendClosed, got %+v", res)
	}
}

func TestSession_SendMessage_SessQueueFull(t *testing.T) {
	s := NewSession().AddInstance()
	s.SetSignonComplete()
	// Fill up the message channel (default buffer size is 1000)
	for i := 0; i < 1000; i++ {
		assert.Equal(t, SessSendOK, s.RelayMessageToInstance(wire.SNACMessage{}))
	}
	assert.Equal(t, SessQueueFull, s.RelayMessageToInstance(wire.SNACMessage{}))
}

func TestSession_Close_Twice(t *testing.T) {
	s := NewSession().AddInstance()
	s.CloseInstance()
	s.CloseInstance() // make sure close is idempotent
	// Check that the session is closed by trying to relay a message
	if res := s.RelayMessageToInstance(wire.SNACMessage{}); res != SessSendClosed {
		t.Fatalf("expected SessSendClosed, got %+v", res)
	}
	select {
	case <-s.Closed():
	case <-time.After(1 * time.Second):
		t.Fatalf("channel is not closed")
	}
}

func TestSession_Closed(t *testing.T) {
	s := NewSession().AddInstance()
	select {
	case <-s.Closed():
		assert.Fail(t, "channel is closed")
	default:
		// channel is open by default
	}
	s.Session().CloseSession()
	<-s.Closed()
}

func TestSession_EvaluateRateLimit_ObserveRateChanges(t *testing.T) {
	classParams := [5]wire.RateClass{
		{
			ID:              1,
			WindowSize:      80,
			ClearLevel:      2500,
			AlertLevel:      2000,
			LimitLevel:      1500,
			DisconnectLevel: 800,
			MaxLevel:        6000,
		},
		{
			ID:              2,
			WindowSize:      80,
			ClearLevel:      3000,
			AlertLevel:      2000,
			LimitLevel:      1500,
			DisconnectLevel: 1000,
			MaxLevel:        6000,
		},
		{
			ID:              3,
			WindowSize:      20,
			ClearLevel:      5100,
			AlertLevel:      5000,
			LimitLevel:      4000,
			DisconnectLevel: 3000,
			MaxLevel:        6000,
		},
		{
			ID:              4,
			WindowSize:      20,
			ClearLevel:      5500,
			AlertLevel:      5300,
			LimitLevel:      4200,
			DisconnectLevel: 3000,
			MaxLevel:        8000,
		},
		{
			ID:              5,
			WindowSize:      10,
			ClearLevel:      5500,
			AlertLevel:      5300,
			LimitLevel:      4200,
			DisconnectLevel: 3000,
			MaxLevel:        8000,
		},
	}
	rateClasses := wire.NewRateLimitClasses(classParams)

	t.Run("we can action every 5 seconds indefinitely without getting rate limited", func(t *testing.T) {
		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		rateClass := rateClasses.Get(3)
		instance.Session().SubscribeRateLimits([]wire.RateLimitClassID{rateClass.ID})

		for i := 0; i < 100; i++ {
			now = now.Add(5 * time.Second)
			have := instance.Session().EvaluateRateLimit(now, rateClass.ID)
			assert.Equal(t, wire.RateLimitStatusClear, have)
		}
	})

	t.Run("reach disconnect threshold", func(t *testing.T) {
		now := time.Now()

		sess := NewSession()
		sess.SetRateClasses(now, rateClasses)
		sess.AddInstance()
		sess.AddInstance()
		sess.AddInstance()

		rateClass := rateClasses.Get(3)
		sess.SubscribeRateLimits([]wire.RateLimitClassID{rateClass.ID})

		// record some event in the rate limiter
		want := []wire.RateLimitStatus{
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusLimited,
			wire.RateLimitStatusDisconnect,
		}
		for i := 0; i < len(want); i++ {
			now = now.Add(1 * time.Second)
			have := sess.EvaluateRateLimit(now, rateClass.ID)
			assert.Equal(t, want[i], have)
		}

		for _, instance := range sess.Instances() {
			select {
			case <-instance.Closed():
			default:
				t.Error("expected session to be closed")
			}
		}
	})

	t.Run("reach rate limit threshold, wait for clear threshold", func(t *testing.T) {
		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		rateClass := rateClasses.Get(3)
		instance.Session().SubscribeRateLimits([]wire.RateLimitClassID{rateClass.ID})

		// first reach the rate limit threshold
		want := []wire.RateLimitStatus{
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusClear,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusAlert,
			wire.RateLimitStatusLimited,
		}
		for i := 0; i < len(want); i++ {
			now = now.Add(1 * time.Second)
			have := instance.Session().EvaluateRateLimit(now, rateClass.ID)
			assert.Equal(t, want[i], have)

			if i > 0 && want[i-1] != want[i] {
				classChanges, rateChanges := instance.Session().ObserveRateChanges(now)
				assert.Empty(t, classChanges)
				if assert.NotEmpty(t, rateChanges) {
					rateDelta := rateChanges[0]
					assert.Equal(t, rateClass, rateDelta.RateClass)
					assert.Equal(t, want[i], rateDelta.CurrentStatus)
					assert.True(t, rateDelta.Subscribed)
					if want[i] == wire.RateLimitStatusLimited {
						assert.True(t, rateDelta.LimitedNow)
					}
				}
			}
		}

		// this is a rearranged moving average formula that determines how many
		// milliseconds it will take to reach the clear threshold
		rateLimitStates := instance.RateLimitStates()
		timeToRecover := int(math.Ceil((time.Duration(rateClass.ClearLevel*rateClass.WindowSize-rateLimitStates[rateClass.ID-1].CurrentLevel*(rateClass.WindowSize-1)) * time.Millisecond).Seconds()))
		assert.True(t, timeToRecover > 0)

		// indicate the time rate limiting kicked in
		timeLimited := now

		for i := 0; i < timeToRecover; i++ {
			now = now.Add(1 * time.Second)
			classDelta, stateDelta := instance.Session().ObserveRateChanges(now)
			assert.Empty(t, classDelta)

			if i == timeToRecover-1 {
				// assert that the clear threshold has been met.
				assert.ElementsMatch(t, stateDelta, []RateClassState{
					{
						RateClass:     rateClass,
						CurrentLevel:  5140,
						CurrentStatus: wire.RateLimitStatusClear,
						LastTime:      timeLimited,
						Subscribed:    true,
						LimitedNow:    false,
					}})
			} else {
				// assert that no changed have been observed, it's still rate-limited
				assert.Nil(t, stateDelta)
			}
		}
	})

	t.Run("observe a rate class change", func(t *testing.T) {
		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		rateClass := rateClasses.Get(3)
		instance.Session().SubscribeRateLimits([]wire.RateLimitClassID{rateClass.ID})

		now = now.Add(1 * time.Second)
		classDelta, stateDelta := instance.Session().ObserveRateChanges(now)
		assert.Empty(t, classDelta)
		assert.Empty(t, stateDelta)

		paramsCopy := classParams
		paramsCopy[rateClass.ID-1].LimitLevel++

		newRateClasses := wire.NewRateLimitClasses(paramsCopy)

		now = now.Add(1 * time.Second)
		instance.Session().SetRateClasses(now, newRateClasses)

		now = now.Add(1 * time.Second)
		classDelta, stateDelta = instance.Session().ObserveRateChanges(now)
		assert.Equal(t, classDelta[0].RateClass, newRateClasses.Get(rateClass.ID))
		assert.Empty(t, stateDelta)
	})

	t.Run("as a bot, I can action every second indefinitely without getting rate limited", func(t *testing.T) {
		now := time.Now()

		instance := NewSession().AddInstance()
		instance.SetUserInfoFlag(wire.OServiceUserFlagBot)
		instance.Session().SetRateClasses(now, rateClasses)

		for i := 0; i < 100; i++ {
			now = now.Add(1 * time.Second)
			have := instance.Session().EvaluateRateLimit(now, wire.RateLimitClassID(1))
			assert.Equal(t, wire.RateLimitStatusClear, have)
		}
	})
}

func TestSession_SetAndGetFoodGroupVersions(t *testing.T) {
	versions := [wire.MDir + 1]uint16{}
	versions[wire.Feedbag] = 1
	versions[wire.OService] = 2

	s := NewSession().AddInstance()
	s.SetFoodGroupVersions(versions)

	assert.Equal(t, versions, s.FoodGroupVersions())
}

func TestSession_SetAndGetTypingEventsEnabled(t *testing.T) {
	s := NewSession().AddInstance()
	assert.False(t, s.TypingEventsEnabled())
	s.Session().SetTypingEventsEnabled(true)
	assert.True(t, s.TypingEventsEnabled())
	s.Session().SetTypingEventsEnabled(false)
	assert.False(t, s.TypingEventsEnabled())
}

func TestSession_SetAndGetMultiConnFlag(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Zero(t, s.MultiConnFlag())

	s.SetMultiConnFlag(wire.MultiConnFlagsOldClient)
	assert.Equal(t, wire.MultiConnFlagsOldClient, s.MultiConnFlag())

	s.SetMultiConnFlag(wire.MultiConnFlagsRecentClient)
	assert.Equal(t, wire.MultiConnFlagsRecentClient, s.MultiConnFlag())

	s.SetMultiConnFlag(wire.MultiConnFlagsSingleClient)
	assert.Equal(t, wire.MultiConnFlagsSingleClient, s.MultiConnFlag())
}

func TestSession_SetAndGetLastWarnLevel(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Zero(t, s.Warning())

	level := uint16(500)
	s.Session().SetWarning(level)
	assert.Equal(t, level, s.Warning())
}

func TestSessionInstance_ContactsInit(t *testing.T) {
	instance := NewSession().AddInstance()
	assert.False(t, instance.ContactsInit())

	instance.SetContactsInit()
	assert.True(t, instance.ContactsInit())

	instance.SetContactsInit()
	assert.True(t, instance.ContactsInit())
}

func TestInstance_Active(t *testing.T) {
	tests := []struct {
		name           string
		setupInstance  func() *SessionInstance
		expectedActive bool
	}{
		{
			name: "active instance - not closed, not idle, no away message",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:        sg,
					closed:         false,
					idle:           false,
					awayMsg:        "",
					signonComplete: true,
				}
				return instance
			},
			expectedActive: true,
		},
		{
			name: "inactive instance - closed",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session: sg,
					closed:  true,
					idle:    false,
					awayMsg: "",
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - idle",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session: sg,
					closed:  false,
					idle:    true,
					awayMsg: "",
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - has away message",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:         sg,
					closed:          false,
					idle:            false,
					awayMsg:         "I'm away",
					userInfoBitmask: wire.OServiceUserFlagUnavailable,
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - closed and idle",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session: sg,
					closed:  true,
					idle:    true,
					awayMsg: "",
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - closed and has away message",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:         sg,
					closed:          true,
					idle:            false,
					awayMsg:         "I'm away",
					userInfoBitmask: wire.OServiceUserFlagUnavailable,
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - idle and has away message",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:         sg,
					closed:          false,
					idle:            true,
					awayMsg:         "I'm away",
					userInfoBitmask: wire.OServiceUserFlagUnavailable,
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - closed, idle, and has away message",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:         sg,
					closed:          true,
					idle:            true,
					awayMsg:         "I'm away",
					userInfoBitmask: wire.OServiceUserFlagUnavailable,
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - signon not complete",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:        sg,
					closed:         false,
					idle:           false,
					awayMsg:        "",
					signonComplete: false,
				}
				return instance
			},
			expectedActive: false,
		},
		{
			name: "inactive instance - signon not complete and idle",
			setupInstance: func() *SessionInstance {
				sg := NewSession()
				instance := &SessionInstance{
					session:        sg,
					closed:         false,
					idle:           true,
					awayMsg:        "",
					signonComplete: false,
				}
				return instance
			},
			expectedActive: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			instance := tt.setupInstance()
			assert.Equal(t, tt.expectedActive, instance.active())
		})
	}
}

func TestSessionGroup_AllInactive(t *testing.T) {
	tests := []struct {
		name              string
		setupSessionGroup func() *Session
		expectedResult    bool
	}{
		{
			name: "no instances - should return true",
			setupSessionGroup: func() *Session {
				return NewSession()
			},
			expectedResult: true,
		},
		{
			name: "one active instance - should return false",
			setupSessionGroup: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.closed = false
				instance.idle = false
				instance.awayMsg = ""
				instance.signonComplete = true
				return sg
			},
			expectedResult: false,
		},
		{
			name: "one closed instance - should return true",
			setupSessionGroup: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.closed = true
				instance.idle = false
				instance.awayMsg = ""
				return sg
			},
			expectedResult: true,
		},
		{
			name: "one idle instance - should return true",
			setupSessionGroup: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.closed = false
				instance.idle = true
				instance.awayMsg = ""
				return sg
			},
			expectedResult: true,
		},
		{
			name: "one instance with away message - should return true",
			setupSessionGroup: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.closed = false
				instance.idle = false
				instance.awayMsg = "I'm away"
				return sg
			},
			expectedResult: true,
		},
		{
			name: "multiple instances - all inactive - should return true",
			setupSessionGroup: func() *Session {
				sg := NewSession()

				// Add closed instance
				instance1 := sg.AddInstance()
				instance1.closed = true
				instance1.idle = false
				instance1.awayMsg = ""

				// Add idle instance
				instance2 := sg.AddInstance()
				instance2.closed = false
				instance2.idle = true
				instance2.awayMsg = ""

				// Add instance with away message
				instance3 := sg.AddInstance()
				instance3.closed = false
				instance3.idle = false
				instance3.awayMsg = "I'm away"

				return sg
			},
			expectedResult: true,
		},
		{
			name: "multiple instances - one active - should return false",
			setupSessionGroup: func() *Session {
				sg := NewSession()

				// Add closed instance
				instance1 := sg.AddInstance()
				instance1.closed = true
				instance1.idle = false
				instance1.awayMsg = ""

				// Add active instance
				instance2 := sg.AddInstance()
				instance2.closed = false
				instance2.idle = false
				instance2.awayMsg = ""
				instance2.signonComplete = true

				// Add idle instance
				instance3 := sg.AddInstance()
				instance3.closed = false
				instance3.idle = true
				instance3.awayMsg = ""

				return sg
			},
			expectedResult: false,
		},
		{
			name: "multiple instances - all active - should return false",
			setupSessionGroup: func() *Session {
				sg := NewSession()

				// Add first active instance
				instance1 := sg.AddInstance()
				instance1.closed = false
				instance1.idle = false
				instance1.awayMsg = ""
				instance1.signonComplete = true

				// Add second active instance
				instance2 := sg.AddInstance()
				instance2.closed = false
				instance2.idle = false
				instance2.awayMsg = ""
				instance2.signonComplete = true

				return sg
			},
			expectedResult: false,
		},
		{
			name: "mixed scenarios - some closed, some idle, some away, one active - should return false",
			setupSessionGroup: func() *Session {
				sg := NewSession()

				// Add closed instance
				instance1 := sg.AddInstance()
				instance1.closed = true
				instance1.idle = false
				instance1.awayMsg = ""

				// Add idle instance
				instance2 := sg.AddInstance()
				instance2.closed = false
				instance2.idle = true
				instance2.awayMsg = ""

				// Add instance with away message
				instance3 := sg.AddInstance()
				instance3.closed = false
				instance3.idle = false
				instance3.awayMsg = "I'm away"

				// Add active instance
				instance4 := sg.AddInstance()
				instance4.closed = false
				instance4.idle = false
				instance4.awayMsg = ""
				instance4.signonComplete = true

				return sg
			},
			expectedResult: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			sg := tt.setupSessionGroup()
			assert.Equal(t, tt.expectedResult, sg.Inactive())
		})
	}
}

func TestSessionGroup_InstanceCount(t *testing.T) {
	tests := []struct {
		name          string
		setupGroup    func() *Session
		expectedCount int
	}{
		{
			name: "empty session group should return 0",
			setupGroup: func() *Session {
				return NewSession()
			},
			expectedCount: 0,
		},
		{
			name: "one instance should return 1",
			setupGroup: func() *Session {
				sg := NewSession()
				sg.AddInstance()
				return sg
			},
			expectedCount: 1,
		},
		{
			name: "multiple instances should return correct count",
			setupGroup: func() *Session {
				sg := NewSession()
				for i := 0; i < 3; i++ {
					sg.AddInstance()
				}
				return sg
			},
			expectedCount: 3,
		},
		{
			name: "instance count decreases after removal",
			setupGroup: func() *Session {
				sg := NewSession()
				sg.AddInstance()
				instance2 := sg.AddInstance()
				sg.AddInstance()
				// Remove one instance
				sg.RemoveInstance(instance2)
				return sg
			},
			expectedCount: 2,
		},
		{
			name: "instance count is correct after multiple add/remove operations",
			setupGroup: func() *Session {
				sg := NewSession()
				instance1 := sg.AddInstance()
				sg.AddInstance()
				sg.RemoveInstance(instance1)
				sg.AddInstance()
				return sg
			},
			expectedCount: 2,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			sg := tt.setupGroup()
			assert.Equal(t, tt.expectedCount, sg.InstanceCount())
		})
	}
}

func TestSessionGroup_Instances(t *testing.T) {
	tests := []struct {
		name          string
		setupGroup    func() *Session
		expectedCount int
		expectedAll   bool // whether all instances should be returned (including non-signed-in)
	}{
		{
			name: "empty session group should return empty slice",
			setupGroup: func() *Session {
				return NewSession()
			},
			expectedCount: 0,
			expectedAll:   true,
		},
		{
			name: "returns all instances including non-signed-in",
			setupGroup: func() *Session {
				sg := NewSession()
				instance1 := sg.AddInstance()
				instance1.SetSignonComplete()
				_ = sg.AddInstance()
				// instance2 has not completed signon
				return sg
			},
			expectedCount: 2,
			expectedAll:   true,
		},
		{
			name: "returns all instances with mixed signon states",
			setupGroup: func() *Session {
				sg := NewSession()
				instance1 := sg.AddInstance()
				instance1.SetSignonComplete()
				_ = sg.AddInstance()
				// instance2 has not completed signon
				instance3 := sg.AddInstance()
				instance3.SetSignonComplete()
				return sg
			},
			expectedCount: 3,
			expectedAll:   true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			sg := tt.setupGroup()
			instances := sg.Instances()
			assert.Equal(t, tt.expectedCount, len(instances), "should return all instances")

			if tt.expectedAll {
				// Verify that instances() returns all instances regardless of their state
				// This is the key change: it should return all instances, not just live ones
				assert.Equal(t, sg.InstanceCount(), len(instances), "Instances() should return all instances")
			}
		})
	}
}

func TestSession_SetAndGetProfile(t *testing.T) {
	s := NewSession().AddInstance()
	profile := s.Session().Profile()
	assert.Empty(t, profile.ProfileText)
	assert.Empty(t, profile.MIMEType)
	assert.True(t, profile.UpdateTime.IsZero())

	profileTime := time.Unix(1234567890, 0)
	newProfile := UserProfile{
		ProfileText: "My profile text",
		MIMEType:    "text/plain",
		UpdateTime:  profileTime,
	}
	s.SetProfile(newProfile)
	retrievedProfile := s.Session().Profile()
	assert.Equal(t, newProfile, retrievedProfile)
	assert.Equal(t, "My profile text", retrievedProfile.ProfileText)
	assert.Equal(t, "text/plain", retrievedProfile.MIMEType)
	assert.Equal(t, profileTime, retrievedProfile.UpdateTime)
}

func TestSession_Profile(t *testing.T) {
	tests := []struct {
		name            string
		setupSession    func() *Session
		expectedProfile UserProfile
	}{
		{
			name: "no instances - returns empty profile",
			setupSession: func() *Session {
				return NewSession()
			},
			expectedProfile: UserProfile{},
		},
		{
			name: "one instance with empty profile - returns empty profile",
			setupSession: func() *Session {
				s := NewSession()
				s.AddInstance()
				return s
			},
			expectedProfile: UserProfile{},
		},
		{
			name: "one instance with non-empty profile - returns that profile",
			setupSession: func() *Session {
				s := NewSession()
				instance := s.AddInstance()
				profileTime := time.Unix(1234567890, 0)
				instance.SetProfile(UserProfile{
					ProfileText: "My profile",
					MIMEType:    "text/plain",
					UpdateTime:  profileTime,
				})
				return s
			},
			expectedProfile: UserProfile{
				ProfileText: "My profile",
				MIMEType:    "text/plain",
				UpdateTime:  time.Unix(1234567890, 0),
			},
		},
		{
			name: "multiple instances, all empty - returns empty profile",
			setupSession: func() *Session {
				s := NewSession()
				s.AddInstance()
				s.AddInstance()
				s.AddInstance()
				return s
			},
			expectedProfile: UserProfile{},
		},
		{
			name: "multiple instances, one non-empty - returns that one",
			setupSession: func() *Session {
				s := NewSession()
				s.AddInstance() // empty instance
				instance2 := s.AddInstance()
				instance2.SetProfile(UserProfile{
					ProfileText: "Profile 2",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567890, 0),
				})
				s.AddInstance() // empty instance
				return s
			},
			expectedProfile: UserProfile{
				ProfileText: "Profile 2",
				MIMEType:    "text/plain",
				UpdateTime:  time.Unix(1234567890, 0),
			},
		},
		{
			name: "multiple instances, multiple non-empty - returns most recent UpdateTime",
			setupSession: func() *Session {
				s := NewSession()
				instance1 := s.AddInstance()
				instance1.SetProfile(UserProfile{
					ProfileText: "Profile 1",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567900, 0), // later time - should be returned
				})
				instance2 := s.AddInstance()
				instance2.SetProfile(UserProfile{
					ProfileText: "Profile 2",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567890, 0), // earlier time
				})
				instance3 := s.AddInstance()
				instance3.SetProfile(UserProfile{
					ProfileText: "Profile 3",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567895, 0), // middle time
				})
				return s
			},
			expectedProfile: UserProfile{
				ProfileText: "Profile 1",
				MIMEType:    "text/plain",
				UpdateTime:  time.Unix(1234567900, 0),
			},
		},
		{
			name: "first instance empty, later instances have profiles - returns most recent non-empty",
			setupSession: func() *Session {
				s := NewSession()
				s.AddInstance() // empty instance
				instance2 := s.AddInstance()
				instance2.SetProfile(UserProfile{
					ProfileText: "Profile 2",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567890, 0), // earlier
				})
				instance3 := s.AddInstance()
				instance3.SetProfile(UserProfile{
					ProfileText: "Profile 3",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567900, 0), // later time - should be returned
				})
				return s
			},
			expectedProfile: UserProfile{
				ProfileText: "Profile 3",
				MIMEType:    "text/plain",
				UpdateTime:  time.Unix(1234567900, 0),
			},
		},
		{
			name: "profile with empty ProfileText is considered empty",
			setupSession: func() *Session {
				s := NewSession()
				instance := s.AddInstance()
				instance.SetProfile(UserProfile{
					ProfileText: "",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567890, 0),
				})
				return s
			},
			expectedProfile: UserProfile{},
		},
		{
			name: "profile with null byte ProfileText is considered empty",
			setupSession: func() *Session {
				s := NewSession()
				instance := s.AddInstance()
				instance.SetProfile(UserProfile{
					ProfileText: "\x00",
					MIMEType:    "text/plain",
					UpdateTime:  time.Unix(1234567890, 0),
				})
				return s
			},
			expectedProfile: UserProfile{},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			s := tt.setupSession()
			profile := s.Profile()
			assert.Equal(t, tt.expectedProfile, profile)
		})
	}
}

func TestSession_SetAndGetMemberSince(t *testing.T) {
	s := NewSession().AddInstance()
	assert.True(t, s.Session().MemberSince().IsZero())

	memberTime := time.Unix(1234567890, 0)
	s.Session().SetMemberSince(memberTime)
	assert.Equal(t, memberTime, s.Session().MemberSince())
}

func TestSession_SetAndGetOfflineMsgCount(t *testing.T) {
	s := NewSession().AddInstance()
	assert.Zero(t, s.OfflineMsgCount())

	count := 5
	s.Session().SetOfflineMsgCount(count)
	assert.Equal(t, count, s.OfflineMsgCount())

	count = 10
	s.Session().SetOfflineMsgCount(count)
	assert.Equal(t, count, s.OfflineMsgCount())
}

func TestSession_ScaleWarningAndRateLimit(t *testing.T) {
	t.Run("scale up", func(t *testing.T) {
		classParams := [5]wire.RateClass{
			{},
			{},
			{
				ID:              3,
				WindowSize:      20,
				ClearLevel:      5100,
				AlertLevel:      5000,
				LimitLevel:      4000,
				DisconnectLevel: 3000,
				MaxLevel:        6000,
			},
			{},
			{},
		}
		rateClasses := wire.NewRateLimitClasses(classParams)

		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		var wg sync.WaitGroup
		wg.Add(1)

		ctx, cancel := context.WithCancel(t.Context())
		go func() {
			defer wg.Done()
			for {
				select {
				case <-ctx.Done():
					return
				case <-instance.WarningCh():
				}
			}
		}()

		rateLimitStates := instance.RateLimitStates()
		assert.Equal(t, int32(5000), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5100), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4000), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5085), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5175), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4185), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5170), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5250), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4370), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5255), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5325), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4555), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5340), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5400), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4740), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5425), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5475), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4925), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5510), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5550), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5110), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5595), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5625), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5295), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5680), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5700), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5480), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5765), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5775), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5665), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5850), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5850), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].LimitLevel)

		cancel()
		wg.Wait()
	})

	t.Run("scale down", func(t *testing.T) {
		currentClassParams := [5]wire.RateClass{
			{},
			{},
			{
				ID:              3,
				WindowSize:      20,
				ClearLevel:      5100,
				AlertLevel:      5000,
				LimitLevel:      4000,
				DisconnectLevel: 3000,
				MaxLevel:        6000,
			},
			{},
			{},
		}
		rateClasses := wire.NewRateLimitClasses(currentClassParams)

		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		var wg sync.WaitGroup
		wg.Add(1)

		ctx, cancel := context.WithCancel(t.Context())
		go func() {
			defer wg.Done()
			for {
				select {
				case <-ctx.Done():
					return
				case <-instance.WarningCh():
				}
			}
		}()

		for i := 0; i < 10; i++ {
			instance.Session().ScaleWarningAndRateLimit(100, 3)
		}

		rateLimitStates := instance.RateLimitStates()
		assert.Equal(t, int32(5850), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5765), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5775), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5665), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5680), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5700), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5480), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5595), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5625), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5295), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5510), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5550), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5110), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5425), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5475), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4925), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5340), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5400), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4740), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5255), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5325), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4555), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5170), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5250), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4370), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5085), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5175), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4185), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5000), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5100), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4000), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(-100, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5000), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5100), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4000), rateLimitStates[2].LimitLevel)

		cancel()
		wg.Wait()
	})

	t.Run("increment 100%", func(t *testing.T) {
		classParams := [5]wire.RateClass{
			{},
			{},
			{
				ID:              3,
				WindowSize:      20,
				ClearLevel:      5100,
				AlertLevel:      5000,
				LimitLevel:      4000,
				DisconnectLevel: 3000,
				MaxLevel:        6000,
			},
			{},
			{},
		}
		rateClasses := wire.NewRateLimitClasses(classParams)

		now := time.Now()

		instance := NewSession().AddInstance()
		instance.Session().SetRateClasses(now, rateClasses)

		var wg sync.WaitGroup
		wg.Add(1)

		ctx, cancel := context.WithCancel(t.Context())
		go func() {
			defer wg.Done()
			for {
				select {
				case <-ctx.Done():
					return
				case <-instance.WarningCh():
				}
			}
		}()

		rateLimitStates := instance.RateLimitStates()
		assert.Equal(t, int32(5000), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5100), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(4000), rateLimitStates[2].LimitLevel)

		instance.Session().ScaleWarningAndRateLimit(1000, 3)
		rateLimitStates = instance.RateLimitStates()
		assert.Equal(t, int32(5850), rateLimitStates[2].AlertLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].ClearLevel)
		assert.Equal(t, int32(5850), rateLimitStates[2].LimitLevel)

		cancel()
		wg.Wait()
	})
}

func TestSession_RunOnce(t *testing.T) {
	t.Run("runs function on first call", func(t *testing.T) {
		s := NewSession()
		callCount := 0

		err := s.RunOnce(func() error {
			callCount++
			return nil
		})

		assert.NoError(t, err)
		assert.Equal(t, 1, callCount)
	})

	t.Run("does not run function on subsequent calls", func(t *testing.T) {
		s := NewSession()
		callCount := 0

		// First call
		err1 := s.RunOnce(func() error {
			callCount++
			return nil
		})

		// Second call
		err2 := s.RunOnce(func() error {
			callCount++
			return nil
		})

		// Third call
		err3 := s.RunOnce(func() error {
			callCount++
			return nil
		})

		assert.NoError(t, err1)
		assert.NoError(t, err2)
		assert.NoError(t, err3)
		assert.Equal(t, 1, callCount, "function should only be called once")
	})

	t.Run("returns error from function", func(t *testing.T) {
		s := NewSession()
		expectedErr := assert.AnError

		err := s.RunOnce(func() error {
			return expectedErr
		})

		assert.Error(t, err)
		assert.Equal(t, expectedErr, err)
	})

	// Init is one-shot, so a session that failed to initialize must not linger for
	// later instances to attach to.
	t.Run("closes the session when the function fails", func(t *testing.T) {
		s := NewSession()
		instance := s.AddInstance()

		err := s.RunOnce(func() error {
			return assert.AnError
		})

		assert.Error(t, err)
		assert.True(t, s.IsClosed(), "session should be closed after a failed init")
		assert.True(t, instance.IsClosed(), "instances should be torn down with the session")
	})

	t.Run("leaves the session open when the function succeeds", func(t *testing.T) {
		s := NewSession()
		s.AddInstance()

		assert.NoError(t, s.RunOnce(func() error { return nil }))
		assert.False(t, s.IsClosed())
	})

	// A failed init tears the session down, so a caller that did not run fn must
	// still learn it failed rather than sign a client on to a session whose
	// instances have just been closed underneath it.
	t.Run("reports the init error to every caller", func(t *testing.T) {
		s := NewSession()
		s.AddInstance()

		first := s.RunOnce(func() error { return assert.AnError })
		second := s.RunOnce(func() error { return nil })

		assert.ErrorIs(t, first, assert.AnError)
		assert.ErrorIs(t, second, assert.AnError, "the caller that did not run fn must not read failure as success")
	})

	// Two instances can be added to a fresh session and reach RunOnce
	// concurrently. Whichever one loses the race still has a client to sign on,
	// and must be told the session is not usable.
	t.Run("reports the init error to a concurrent caller", func(t *testing.T) {
		synctest.Test(t, func(t *testing.T) {
			s := NewSession()
			s.AddInstance()
			s.AddInstance()

			var wg sync.WaitGroup
			errs := make([]error, 2)
			for i := range errs {
				wg.Add(1)
				go func() {
					defer wg.Done()
					errs[i] = s.RunOnce(func() error { return assert.AnError })
				}()
			}
			wg.Wait()

			for i, err := range errs {
				assert.ErrorIs(t, err, assert.AnError, "caller %d", i)
			}
		})
	})
}

// An instance added to a closed session is live but orphaned: Closed() has
// already fired, so the per-account goroutines that select on it — the rate limit
// monitor above all — have exited, and RunOnce is spent so nothing restarts them.
// AddInstance must refuse, so AddSession can fall through to the tombstone wait it
// already implements.
func TestSession_AddInstance_RefusesClosedSession(t *testing.T) {
	s := NewSession()
	first := s.AddInstance()

	// Stand in for OServiceService.MonitorRateLimits: a per-account goroutine
	// started from RunOnce that runs until the session closes.
	require.NoError(t, s.RunOnce(func() error { return nil }))
	monitorDone := make(chan struct{})
	go func() {
		defer close(monitorDone)
		<-s.Closed()
	}()

	// The account's last instance departs, closing the session and stopping the
	// monitor. This is the moment AddSession's IsClosed check races.
	first.CloseInstance()
	select {
	case <-monitorDone:
	case <-time.After(2 * time.Second):
		t.Fatal("monitor did not exit when the session closed")
	}

	assert.Nil(t, s.AddInstance(), "AddInstance must refuse a closed session")

	// RunOnce is spent, so an instance that did attach could never start a
	// replacement monitor.
	ran := false
	assert.NoError(t, s.RunOnce(func() error { ran = true; return nil }))
	assert.False(t, ran)
}

func TestSession_CloseInstance(t *testing.T) {
	s := NewSession()
	sessionCloseCount := 0

	s.OnSessionClose(func() {
		sessionCloseCount++
	})

	instance1CloseCount := 0
	instance2CloseCount := 0
	instance3CloseCount := 0

	instance1 := s.AddInstance()
	instance2 := s.AddInstance()
	instance3 := s.AddInstance()

	instance1.OnClose(func() {
		// ensure instance is removed from the session before calling this func
		assert.Equal(t, 2, s.InstanceCount())
		instance1CloseCount++
	})
	instance2.OnClose(func() {
		assert.Equal(t, 1, s.InstanceCount())
		instance2CloseCount++
	})
	instance3.OnClose(func() {
		instance3CloseCount++
	})

	// Close instance1 (instances 2 and 3 remain)
	instance1.CloseInstance()
	instance2.CloseInstance()
	instance3.CloseInstance()

	assert.Equal(t, 1, instance1CloseCount, "instance1 onInstanceCloseFn should only be called once")
	assert.Equal(t, 1, instance2CloseCount, "instance2 onInstanceCloseFn should only be called once")
	assert.Equal(t, 0, instance3CloseCount, "instance3 onInstanceCloseFn should not be called because it's the last instance")
	assert.Equal(t, 1, sessionCloseCount, "session onSessCloseFn should not be called")
}

func TestSession_CloseSession(t *testing.T) {
	s := NewSession()
	sessionCloseCount := 0

	s.OnSessionClose(func() {
		sessionCloseCount++
	})

	instance1CloseCount := 0
	instance2CloseCount := 0
	instance3CloseCount := 0

	instance1 := s.AddInstance()
	instance2 := s.AddInstance()
	instance3 := s.AddInstance()

	instance1.OnClose(func() {
		instance1CloseCount++
	})
	instance2.OnClose(func() {
		instance2CloseCount++
	})
	instance3.OnClose(func() {
		instance3CloseCount++
	})

	s.CloseSession()

	assert.Equal(t, 0, instance1CloseCount, "instance1 onInstanceCloseFn should not be called")
	assert.Equal(t, 0, instance2CloseCount, "instance2 onInstanceCloseFn should not be called")
	assert.Equal(t, 0, instance3CloseCount, "instance3 onInstanceCloseFn should not be called")
	assert.Equal(t, 1, sessionCloseCount, "session onSessCloseFn should only be called once")
}

func TestSession_AwayMessage(t *testing.T) {
	tests := []struct {
		name           string
		setupSession   func() *Session
		expectedResult string
	}{
		{
			name: "no instances - should return empty string",
			setupSession: func() *Session {
				return NewSession()
			},
			expectedResult: "",
		},
		{
			name: "one instance not away - should return empty string",
			setupSession: func() *Session {
				sg := NewSession()
				_ = sg.AddInstance()
				// instance has no away message and is not set as away
				return sg
			},
			expectedResult: "",
		},
		{
			name: "one instance away via SetUserInfoFlag - should return away message",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance.SetAwayMessage("I'm away")
				return sg
			},
			expectedResult: "I'm away",
		},
		{
			name: "one instance away via SetUserStatusBitmask - should return away message",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.SetUserStatusBitmask(wire.OServiceUserStatusAway)
				instance.SetAwayMessage("I'm away")
				return sg
			},
			expectedResult: "I'm away",
		},
		{
			name: "multiple instances - not all away - should return away message from away instance",
			setupSession: func() *Session {
				sg := NewSession()
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("I'm away")
				_ = sg.AddInstance()
				// instance2 has no away message and is not set as away
				return sg
			},
			expectedResult: "I'm away",
		},
		{
			name: "multiple instances - all away - should return latest away message",
			setupSession: func() *Session {
				sg := NewSession()
				baseTime := time.Now()
				callCount := 0
				sg.nowFn = func() time.Time {
					callCount++
					return baseTime.Add(time.Duration(callCount) * time.Second)
				}
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("First away message")
				instance2 := sg.AddInstance()
				instance2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance2.SetAwayMessage("Second away message")
				return sg
			},
			expectedResult: "Second away message",
		},
		{
			name: "multiple instances - all away after multiple updates - should return latest away message",
			setupSession: func() *Session {
				sg := NewSession()
				baseTime := time.Now()
				callCount := 0
				sg.nowFn = func() time.Time {
					callCount++
					return baseTime.Add(time.Duration(callCount) * time.Second)
				}
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("First away message")
				instance2 := sg.AddInstance()
				instance2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance2.SetAwayMessage("Second away message")
				// Update instance1's away status again (this will update awayTime)
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("Third away message")
				return sg
			},
			expectedResult: "Third away message",
		},
		{
			name: "multiple instances - different away methods - should return latest away message",
			setupSession: func() *Session {
				sg := NewSession()
				baseTime := time.Now()
				callCount := 0
				sg.nowFn = func() time.Time {
					callCount++
					return baseTime.Add(time.Duration(callCount) * time.Second)
				}
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("First away message")
				instance2 := sg.AddInstance()
				instance2.SetUserStatusBitmask(wire.OServiceUserStatusAway)
				instance2.SetAwayMessage("Second away message")
				return sg
			},
			expectedResult: "Second away message",
		},
		{
			name: "instance sets away message then clears message - should return empty string",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance.SetAwayMessage("I'm away")
				instance.SetAwayMessage("") // clear away message (but still away)
				return sg
			},
			expectedResult: "",
		},
		{
			name: "instance sets away message then clears away status - should return empty string",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				instance.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance.SetAwayMessage("I'm away")
				instance.ClearUserInfoFlag(wire.OServiceUserFlagUnavailable) // clear away status
				return sg
			},
			expectedResult: "",
		},
		{
			name: "multiple instances - one away with message, one away without message - should return message from most recent",
			setupSession: func() *Session {
				sg := NewSession()
				baseTime := time.Now()
				callCount := 0
				sg.nowFn = func() time.Time {
					callCount++
					return baseTime.Add(time.Duration(callCount) * time.Second)
				}
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("I'm away")
				instance2 := sg.AddInstance()
				instance2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// instance2 is away but has no message, and was set away after instance1
				return sg
			},
			expectedResult: "", // instance2 has more recent awayTime but no message
		},
		{
			name: "multiple instances - one away with message set later - should return that message",
			setupSession: func() *Session {
				sg := NewSession()
				baseTime := time.Now()
				callCount := 0
				sg.nowFn = func() time.Time {
					callCount++
					return baseTime.Add(time.Duration(callCount) * time.Second)
				}
				instance1 := sg.AddInstance()
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				instance1.SetAwayMessage("I'm away")
				instance2 := sg.AddInstance()
				instance2.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				// instance2 is away but has no message
				// Now update instance1's away status to make it more recent
				instance1.SetUserInfoFlag(wire.OServiceUserFlagUnavailable)
				return sg
			},
			expectedResult: "I'm away", // instance1 has more recent awayTime and has a message
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			sg := tt.setupSession()
			result := sg.AwayMessage()
			assert.Equal(t, tt.expectedResult, result)
		})
	}
}

func TestSession_Caps(t *testing.T) {
	// Helper function to compare capability slices (order-independent)
	capsEqual := func(a, b [][16]byte) bool {
		if len(a) != len(b) {
			return false
		}
		capMap := make(map[[16]byte]bool)
		for _, cap := range a {
			capMap[cap] = true
		}
		for _, cap := range b {
			if !capMap[cap] {
				return false
			}
		}
		return true
	}

	tests := []struct {
		name          string
		setupSession  func() *Session
		expectedCaps  [][16]byte
		expectedCount int
	}{
		{
			name: "empty session with no instances - should return empty slice",
			setupSession: func() *Session {
				return NewSession()
			},
			expectedCaps:  [][16]byte{},
			expectedCount: 0,
		},
		{
			name: "single instance with no capabilities - should return empty slice",
			setupSession: func() *Session {
				sg := NewSession()
				_ = sg.AddInstance()
				return sg
			},
			expectedCaps:  [][16]byte{},
			expectedCount: 0,
		},
		{
			name: "single instance with one cap - should return that cap",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				instance.SetCaps([][16]byte{cap1})
				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
			},
			expectedCount: 1,
		},
		{
			name: "single instance with multiple capabilities - should return all capabilities",
			setupSession: func() *Session {
				sg := NewSession()
				instance := sg.AddInstance()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				cap2 := [16]byte{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01}
				cap3 := [16]byte{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02}
				instance.SetCaps([][16]byte{cap1, cap2, cap3})
				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
				{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01},
				{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02},
			},
			expectedCount: 3,
		},
		{
			name: "multiple instances with no overlapping capabilities - should return union of all capabilities",
			setupSession: func() *Session {
				sg := NewSession()
				instance1 := sg.AddInstance()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				instance1.SetCaps([][16]byte{cap1})

				instance2 := sg.AddInstance()
				cap2 := [16]byte{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01}
				instance2.SetCaps([][16]byte{cap2})

				instance3 := sg.AddInstance()
				cap3 := [16]byte{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02}
				instance3.SetCaps([][16]byte{cap3})

				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
				{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01},
				{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02},
			},
			expectedCount: 3,
		},
		{
			name: "multiple instances with overlapping capabilities - should deduplicate",
			setupSession: func() *Session {
				sg := NewSession()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				cap2 := [16]byte{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01}
				cap3 := [16]byte{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02}

				instance1 := sg.AddInstance()
				instance1.SetCaps([][16]byte{cap1, cap2})

				instance2 := sg.AddInstance()
				instance2.SetCaps([][16]byte{cap2, cap3}) // cap2 overlaps

				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
				{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01},
				{0x76, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x02},
			},
			expectedCount: 3,
		},
		{
			name: "multiple instances with all same capabilities - should return unique capabilities",
			setupSession: func() *Session {
				sg := NewSession()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				cap2 := [16]byte{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01}

				instance1 := sg.AddInstance()
				instance1.SetCaps([][16]byte{cap1, cap2})

				instance2 := sg.AddInstance()
				instance2.SetCaps([][16]byte{cap1, cap2}) // same caps

				instance3 := sg.AddInstance()
				instance3.SetCaps([][16]byte{cap1, cap2}) // same caps

				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
				{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01},
			},
			expectedCount: 2,
		},
		{
			name: "multiple instances with some having capabilities and some not - should return union",
			setupSession: func() *Session {
				sg := NewSession()
				_ = sg.AddInstance()
				// instance1 has no caps

				instance2 := sg.AddInstance()
				cap1 := [16]byte{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00}
				instance2.SetCaps([][16]byte{cap1})

				_ = sg.AddInstance()
				// instance3 has no caps

				instance4 := sg.AddInstance()
				cap2 := [16]byte{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01}
				instance4.SetCaps([][16]byte{cap2})

				return sg
			},
			expectedCaps: [][16]byte{
				{0x74, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x00},
				{0x75, 0x8f, 0x24, 0x20, 0x62, 0x87, 0x11, 0xd1, 0x82, 0x22, 0x44, 0x45, 0x53, 0x54, 0x00, 0x01},
			},
			expectedCount: 2,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			sg := tt.setupSession()
			result := sg.Caps()

			assert.Equal(t, tt.expectedCount, len(result), "cap count should match")
			assert.True(t, capsEqual(tt.expectedCaps, result), "capabilities should match (order-independent)")
		})
	}
}

func TestSession_InstanceNumberAssignment(t *testing.T) {
	t.Run("first instance gets number 1", func(t *testing.T) {
		s := NewSession()
		instance := s.AddInstance()
		assert.Equal(t, uint8(1), instance.Num())
	})

	t.Run("multiple instances get sequential numbers", func(t *testing.T) {
		s := NewSession()
		instance1 := s.AddInstance()
		instance2 := s.AddInstance()
		instance3 := s.AddInstance()

		assert.Equal(t, uint8(1), instance1.Num())
		assert.Equal(t, uint8(2), instance2.Num())
		assert.Equal(t, uint8(3), instance3.Num())
	})

	t.Run("removed instance numbers are reused", func(t *testing.T) {
		s := NewSession()
		instance1 := s.AddInstance()
		instance2 := s.AddInstance()
		instance3 := s.AddInstance()

		assert.Equal(t, uint8(1), instance1.Num())
		assert.Equal(t, uint8(2), instance2.Num())
		assert.Equal(t, uint8(3), instance3.Num())

		// Remove instance 2
		s.RemoveInstance(instance2)

		// New instance should reuse number 2
		instance4 := s.AddInstance()
		assert.Equal(t, uint8(2), instance4.Num())

		// Verify all instance numbers are unique
		instances := s.Instances()
		instanceNums := make(map[uint8]bool)
		for _, inst := range instances {
			assert.False(t, instanceNums[inst.Num()], "instance number %d should be unique", inst.Num())
			instanceNums[inst.Num()] = true
		}
	})

	t.Run("finds lowest available number", func(t *testing.T) {
		s := NewSession()
		// Create instances 1, 2, 3
		instance1 := s.AddInstance()
		instance2 := s.AddInstance()
		instance3 := s.AddInstance()

		assert.Equal(t, uint8(1), instance1.Num())
		assert.Equal(t, uint8(2), instance2.Num())
		assert.Equal(t, uint8(3), instance3.Num())

		// Remove instance 1
		s.RemoveInstance(instance1)

		// New instance should get number 1 (lowest available)
		instance4 := s.AddInstance()
		assert.Equal(t, uint8(1), instance4.Num())

		// Remove instance 2
		s.RemoveInstance(instance2)

		// New instance should get number 2 (lowest available)
		instance5 := s.AddInstance()
		assert.Equal(t, uint8(2), instance5.Num())

		// Verify instance 3 still has its number
		assert.Equal(t, uint8(3), instance3.Num())
	})

	t.Run("panics when all instance numbers are taken", func(t *testing.T) {
		s := NewSession()

		// Fill up all 255 instance numbers
		instances := make([]*SessionInstance, 255)
		for i := 0; i < 255; i++ {
			instances[i] = s.AddInstance()
		}

		// Verify we have 255 instances
		assert.Equal(t, 255, s.InstanceCount())

		// Try to create one more - should panic
		assert.PanicsWithValue(t, "all instance numbers are taken (max 255 instances per session)", func() {
			s.AddInstance()
		})
	})
}