utxonursery_test.go

//go:build !rpctest
// +build !rpctest

package dcrlnd

import (
	"bytes"
	"fmt"
	"math"
	"os"
	"reflect"
	"runtime/pprof"
	"sync"
	"testing"
	"time"

	"github.com/decred/dcrd/chaincfg/chainhash"
	"github.com/decred/dcrd/dcrec/secp256k1/v4"
	"github.com/decred/dcrd/dcrutil/v4"
	"github.com/decred/dcrd/txscript/v4"
	"github.com/decred/dcrd/wire"
	"github.com/decred/dcrlnd/channeldb"
	"github.com/decred/dcrlnd/input"
	"github.com/decred/dcrlnd/lnwallet"
	"github.com/decred/dcrlnd/sweep"
)

var (
	outPoints = []wire.OutPoint{
		{
			Hash: [chainhash.HashSize]byte{
				0x51, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
				0x48, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
				0x2d, 0xe7, 0x93, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
				0x1f, 0xb, 0x4c, 0xf9, 0x9e, 0xc5, 0x8c, 0xe9,
			},
			Index: 9,
		},
		{
			Hash: [chainhash.HashSize]byte{
				0xb7, 0x94, 0x38, 0x5f, 0x2d, 0x1e, 0xf7, 0xab,
				0x4d, 0x92, 0x73, 0xd1, 0x90, 0x63, 0x81, 0xb4,
				0x4f, 0x2f, 0x6f, 0x25, 0x88, 0xa3, 0xef, 0xb9,
				0x6a, 0x49, 0x18, 0x83, 0x31, 0x98, 0x47, 0x53,
			},
			Index: 49,
		},
		{
			Hash: [chainhash.HashSize]byte{
				0x81, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
				0x63, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
				0x0d, 0xe7, 0x95, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
				0x1e, 0xb, 0x4c, 0xfd, 0x9e, 0xc5, 0x8c, 0xe9,
			},
			Index: 23,
		},
		{
			Hash: [chainhash.HashSize]byte{
				0x1e, 0xb, 0x4c, 0xfd, 0x9e, 0xc5, 0x8c, 0xe9,
				0x81, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
				0x0d, 0xe7, 0x95, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
				0x63, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
			},
			Index: 30,
		},
		{
			Hash: [chainhash.HashSize]byte{
				0x0d, 0xe7, 0x95, 0xe4, 0xfc, 0xd2, 0xc6, 0xda,
				0xb7, 0x25, 0xb8, 0x4d, 0x63, 0x59, 0xe6, 0x96,
				0x31, 0x13, 0xa1, 0x17, 0x81, 0xb6, 0x37, 0xd8,
				0x1e, 0x0b, 0x4c, 0xfd, 0x9e, 0xc5, 0x8c, 0xe9,
			},
			Index: 2,
		},
		{
			Hash: [chainhash.HashSize]byte{
				0x48, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
				0x51, 0xb6, 0x37, 0xd8, 0x1f, 0x0b, 0x4c, 0xf9,
				0x9e, 0xc5, 0x8c, 0xe9, 0xfc, 0xd2, 0xc6, 0xda,
				0x2d, 0xe7, 0x93, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
			},
			Index: 9,
		},
	}

	keys = [][]byte{
		{0x04, 0x11, 0xdb, 0x93, 0xe1, 0xdc, 0xdb, 0x8a,
			0x01, 0x6b, 0x49, 0x84, 0x0f, 0x8c, 0x53, 0xbc, 0x1e,
			0xb6, 0x8a, 0x38, 0x2e, 0x97, 0xb1, 0x48, 0x2e, 0xca,
			0xd7, 0xb1, 0x48, 0xa6, 0x90, 0x9a, 0x5c, 0xb2, 0xe0,
			0xea, 0xdd, 0xfb, 0x84, 0xcc, 0xf9, 0x74, 0x44, 0x64,
			0xf8, 0x2e, 0x16, 0x0b, 0xfa, 0x9b, 0x8b, 0x64, 0xf9,
			0xd4, 0xc0, 0x3f, 0x99, 0x9b, 0x86, 0x43, 0xf6, 0x56,
			0xb4, 0x12, 0xa3,
		},
		{0x04, 0x11, 0xdb, 0x93, 0xe1, 0xdc, 0xdb, 0x8a,
			0x01, 0x6b, 0x49, 0x84, 0x0f, 0x8c, 0x53, 0xbc, 0x1e,
			0xb6, 0x8a, 0x38, 0x2e, 0x97, 0xb1, 0x48, 0x2e, 0xca,
			0xd7, 0xb1, 0x48, 0xa6, 0x90, 0x9a, 0x5c, 0xb2, 0xe0,
			0xea, 0xdd, 0xfb, 0x84, 0xcc, 0xf9, 0x74, 0x44, 0x64,
			0xf8, 0x2e, 0x16, 0x0b, 0xfa, 0x9b, 0x8b, 0x64, 0xf9,
			0xd4, 0xc0, 0x3f, 0x99, 0x9b, 0x86, 0x43, 0xf6, 0x56,
			0xb4, 0x12, 0xa3,
		},
		{0x02, 0xce, 0x0b, 0x14, 0xfb, 0x84, 0x2b, 0x1b,
			0xa5, 0x49, 0xfd, 0xd6, 0x75, 0xc9, 0x80, 0x75, 0xf1,
			0x2e, 0x9c, 0x51, 0x0f, 0x8e, 0xf5, 0x2b, 0xd0, 0x21,
			0xa9, 0xa1, 0xf4, 0x80, 0x9d, 0x3b, 0x4d,
		},
	}

	signDescriptors = []input.SignDescriptor{
		{
			SingleTweak: []byte{
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02,
			},
			WitnessScript: []byte{
				0x00, 0x14, 0xee, 0x91, 0x41, 0x7e, 0x85, 0x6c, 0xde,
				0x10, 0xa2, 0x91, 0x1e, 0xdc, 0xbd, 0xbd, 0x69, 0xe2,
				0xef, 0xb5, 0x71, 0x48,
			},
			Output: &wire.TxOut{
				Value: 5000000000,
				PkScript: []byte{
					0x41, // OP_DATA_65
					0x04, 0xd6, 0x4b, 0xdf, 0xd0, 0x9e, 0xb1, 0xc5,
					0xfe, 0x29, 0x5a, 0xbd, 0xeb, 0x1d, 0xca, 0x42,
					0x81, 0xbe, 0x98, 0x8e, 0x2d, 0xa0, 0xb6, 0xc1,
					0xc6, 0xa5, 0x9d, 0xc2, 0x26, 0xc2, 0x86, 0x24,
					0xe1, 0x81, 0x75, 0xe8, 0x51, 0xc9, 0x6b, 0x97,
					0x3d, 0x81, 0xb0, 0x1c, 0xc3, 0x1f, 0x04, 0x78,
					0x34, 0xbc, 0x06, 0xd6, 0xd6, 0xed, 0xf6, 0x20,
					0xd1, 0x84, 0x24, 0x1a, 0x6a, 0xed, 0x8b, 0x63,
					0xa6, // 65-byte signature
					0xac, // OP_CHECKSIG
				},
			},
			HashType: txscript.SigHashAll,
		},
		{
			SingleTweak: []byte{
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02,
			},
			WitnessScript: []byte{
				0x00, 0x14, 0xee, 0x91, 0x41, 0x7e, 0x85, 0x6c, 0xde,
				0x10, 0xa2, 0x91, 0x1e, 0xdc, 0xbd, 0xbd, 0x69, 0xe2,
				0xef, 0xb5, 0x71, 0x48,
			},
			Output: &wire.TxOut{
				Value: 5000000000,
				PkScript: []byte{
					0x41, // OP_DATA_65
					0x04, 0xd6, 0x4b, 0xdf, 0xd0, 0x9e, 0xb1, 0xc5,
					0xfe, 0x29, 0x5a, 0xbd, 0xeb, 0x1d, 0xca, 0x42,
					0x81, 0xbe, 0x98, 0x8e, 0x2d, 0xa0, 0xb6, 0xc1,
					0xc6, 0xa5, 0x9d, 0xc2, 0x26, 0xc2, 0x86, 0x24,
					0xe1, 0x81, 0x75, 0xe8, 0x51, 0xc9, 0x6b, 0x97,
					0x3d, 0x81, 0xb0, 0x1c, 0xc3, 0x1f, 0x04, 0x78,
					0x34, 0xbc, 0x06, 0xd6, 0xd6, 0xed, 0xf6, 0x20,
					0xd1, 0x84, 0x24, 0x1a, 0x6a, 0xed, 0x8b, 0x63,
					0xa6, // 65-byte signature
					0xac, // OP_CHECKSIG
				},
			},
			HashType: txscript.SigHashAll,
		},
		{
			SingleTweak: []byte{
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
				0x02, 0x02, 0x02, 0x02, 0x02,
			},
			WitnessScript: []byte{
				0x00, 0x14, 0xee, 0x91, 0x41, 0x7e, 0x85, 0x6c, 0xde,
				0x10, 0xa2, 0x91, 0x1e, 0xdc, 0xbd, 0xbd, 0x69, 0xe2,
				0xef, 0xb5, 0x71, 0x48,
			},
			Output: &wire.TxOut{
				Value: 5000000000,
				PkScript: []byte{
					0x41, // OP_DATA_65
					0x04, 0xd6, 0x4b, 0xdf, 0xd0, 0x9e, 0xb1, 0xc5,
					0xfe, 0x29, 0x5a, 0xbd, 0xeb, 0x1d, 0xca, 0x42,
					0x81, 0xbe, 0x98, 0x8e, 0x2d, 0xa0, 0xb6, 0xc1,
					0xc6, 0xa5, 0x9d, 0xc2, 0x26, 0xc2, 0x86, 0x24,
					0xe1, 0x81, 0x75, 0xe8, 0x51, 0xc9, 0x6b, 0x97,
					0x3d, 0x81, 0xb0, 0x1c, 0xc3, 0x1f, 0x04, 0x78,
					0x34, 0xbc, 0x06, 0xd6, 0xd6, 0xed, 0xf6, 0x20,
					0xd1, 0x84, 0x24, 0x1a, 0x6a, 0xed, 0x8b, 0x63,
					0xa6, // 65-byte signature
					0xac, // OP_CHECKSIG
				},
			},
			HashType: txscript.SigHashAll,
		},
	}

	kidOutputs = []kidOutput{
		{
			breachedOutput: breachedOutput{
				amt:         dcrutil.Amount(13e7),
				outpoint:    outPoints[1],
				witnessType: input.CommitmentTimeLock,
				confHeight:  uint32(1000),
			},
			originChanPoint:  outPoints[0],
			blocksToMaturity: uint32(42),
		},

		{
			breachedOutput: breachedOutput{
				amt:         dcrutil.Amount(24e7),
				outpoint:    outPoints[2],
				witnessType: input.CommitmentTimeLock,
				confHeight:  uint32(1000),
			},
			originChanPoint:  outPoints[0],
			blocksToMaturity: uint32(42),
		},

		{
			breachedOutput: breachedOutput{
				amt:         dcrutil.Amount(2e5),
				outpoint:    outPoints[3],
				witnessType: input.CommitmentTimeLock,
				confHeight:  uint32(500),
			},
			originChanPoint:  outPoints[0],
			blocksToMaturity: uint32(28),
		},

		{
			breachedOutput: breachedOutput{
				amt:         dcrutil.Amount(10e6),
				outpoint:    outPoints[4],
				witnessType: input.CommitmentTimeLock,
				confHeight:  uint32(500),
			},
			originChanPoint:  outPoints[0],
			blocksToMaturity: uint32(28),
		},
	}

	babyOutputs = []babyOutput{
		{
			kidOutput: kidOutputs[1],
			expiry:    3829,
			timeoutTx: timeoutTx,
		},
		{
			kidOutput: kidOutputs[2],
			expiry:    4,
			timeoutTx: timeoutTx,
		},
		{
			kidOutput: kidOutputs[3],
			expiry:    4,
			timeoutTx: timeoutTx,
		},
	}

	// Dummy timeout tx used to test serialization, borrowed from dcrd
	// msgtx_test
	timeoutTx = &wire.MsgTx{
		Version: 1,
		TxIn: []*wire.TxIn{
			{
				PreviousOutPoint: wire.OutPoint{
					Hash: chainhash.Hash{
						0xa5, 0x33, 0x52, 0xd5, 0x13, 0x57, 0x66, 0xf0,
						0x30, 0x76, 0x59, 0x74, 0x18, 0x26, 0x3d, 0xa2,
						0xd9, 0xc9, 0x58, 0x31, 0x59, 0x68, 0xfe, 0xa8,
						0x23, 0x52, 0x94, 0x67, 0x48, 0x1f, 0xf9, 0xcd,
					},
					Index: 19,
				},
				SignatureScript: []byte{
					// OP_DATA_70
					0x46,

					// 70-byte signature
					0x30, 0x43, 0x02, 0x1f, 0x4d, 0x23, 0x81, 0xdc,
					0x97, 0xf1, 0x82, 0xab, 0xd8, 0x18, 0x5f, 0x51,
					0x75, 0x30, 0x18, 0x52, 0x32, 0x12, 0xf5, 0xdd,
					0xc0, 0x7c, 0xc4, 0xe6, 0x3a, 0x8d, 0xc0, 0x36,
					0x58, 0xda, 0x19, 0x02, 0x20, 0x60, 0x8b, 0x5c,
					0x4d, 0x92, 0xb8, 0x6b, 0x6d, 0xe7, 0xd7, 0x8e,
					0xf2, 0x3a, 0x2f, 0xa7, 0x35, 0xbc, 0xb5, 0x9b,
					0x91, 0x4a, 0x48, 0xb0, 0xe1, 0x87, 0xc5, 0xe7,
					0x56, 0x9a, 0x18, 0x19, 0x70, 0x01,

					// OP_DATA_33
					0x21,

					// 33-byte serialize pub key
					0x03, 0x07, 0xea, 0xd0, 0x84, 0x80, 0x7e, 0xb7,
					0x63, 0x46, 0xdf, 0x69, 0x77, 0x00, 0x0c, 0x89,
					0x39, 0x2f, 0x45, 0xc7, 0x64, 0x25, 0xb2, 0x61,
					0x81, 0xf5, 0x21, 0xd7, 0xf3, 0x70, 0x06, 0x6a,
					0x8f,
				},
				Sequence: 0xffffffff,
			},
		},
		TxOut: []*wire.TxOut{
			{
				Value: 395019,
				PkScript: []byte{ // p2wkh output
					0x00, // Version 0 witness program
					0x14, // OP_DATA_20
					0x9d, 0xda, 0xc6, 0xf3, 0x9d, 0x51, 0xe0, 0x39,
					0x8e, 0x53, 0x2a, 0x22, 0xc4, 0x1b, 0xa1, 0x89,
					0x40, 0x6a, 0x85, 0x23, // 20-byte pub key hash
				},
			},
		},
	}

	testChanPoint      = wire.OutPoint{}
	defaultTestTimeout = 5 * time.Second
)

func init() {
	// Finish initializing our test vectors by parsing the desired public keys and
	// properly populating the sign descriptors of all baby and kid outputs.
	for i := range signDescriptors {
		pk, err := secp256k1.ParsePubKey(keys[i])
		if err != nil {
			panic(fmt.Sprintf("unable to parse pub key during init: %v", err))
		}
		signDescriptors[i].KeyDesc.PubKey = pk

	}
	for i := range kidOutputs {
		isd := i % len(signDescriptors)
		kidOutputs[i].signDesc = signDescriptors[isd]
	}

	for i := range babyOutputs {
		isd := i % len(signDescriptors)
		babyOutputs[i].kidOutput.signDesc = signDescriptors[isd]
	}

	initIncubateTests()
}

func TestKidOutputSerialization(t *testing.T) {
	t.Parallel()

	for i, kid := range kidOutputs {
		var b bytes.Buffer
		if err := kid.Encode(&b); err != nil {
			t.Fatalf("Encode #%d: unable to serialize "+
				"kid output: %v", i, err)
		}

		var deserializedKid kidOutput
		if err := deserializedKid.Decode(&b); err != nil {
			t.Fatalf("Decode #%d: unable to deserialize "+
				"kid output: %v", i, err)
		}

		if !reflect.DeepEqual(kid, deserializedKid) {
			t.Fatalf("DeepEqual #%d: unexpected kidOutput, "+
				"want %+v, got %+v",
				i, kid, deserializedKid)
		}
	}
}

func TestBabyOutputSerialization(t *testing.T) {
	t.Parallel()

	for i, baby := range babyOutputs {
		var b bytes.Buffer
		if err := baby.Encode(&b); err != nil {
			t.Fatalf("Encode #%d: unable to serialize "+
				"baby output: %v", i, err)
		}

		var deserializedBaby babyOutput
		if err := deserializedBaby.Decode(&b); err != nil {
			t.Fatalf("Decode #%d: unable to deserialize "+
				"baby output: %v", i, err)
		}

		if !reflect.DeepEqual(baby, deserializedBaby) {
			t.Fatalf("DeepEqual #%d: unexpected babyOutput, "+
				"want %+v, got %+v",
				i, baby, deserializedBaby)
		}

	}
}

type nurseryTestContext struct {
	nursery     *utxoNursery
	notifier    *sweep.MockNotifier
	chainIO     *mockChainIO
	publishChan chan wire.MsgTx
	store       *nurseryStoreInterceptor
	restart     func() bool
	receiveTx   func() wire.MsgTx
	sweeper     *mockSweeper
	timeoutChan chan chan time.Time
	t           *testing.T
	dbCleanup   func()
}

func createNurseryTestContext(t *testing.T,
	checkStartStop func(func()) bool) *nurseryTestContext {

	// Create a temporary database and connect nurseryStore to it. The
	// alternative, mocking nurseryStore, is not chosen because there is
	// still considerable logic in the store.

	cdb, cleanup, err := channeldb.MakeTestDB()
	if err != nil {
		t.Fatalf("unable to open channeldb: %v", err)
	}

	store, err := newNurseryStore(&chainhash.Hash{}, cdb)
	if err != nil {
		t.Fatal(err)
	}

	// Wrap the store in an inceptor to be able to wait for events in this
	// test.
	storeIntercepter := newNurseryStoreInterceptor(store)

	notifier := sweep.NewMockNotifier(t)

	publishChan := make(chan wire.MsgTx, 1)
	publishFunc := func(tx *wire.MsgTx, source string) error {
		utxnLog.Tracef("Publishing tx %v by %v", tx.TxHash(), source)
		publishChan <- *tx
		return nil
	}

	timeoutChan := make(chan chan time.Time)

	chainIO := &mockChainIO{
		bestHeight: 0,
	}

	sweeper := newMockSweeper(t)

	nurseryCfg := NurseryConfig{
		Notifier: notifier,
		FetchClosedChannels: func(pendingOnly bool) (
			[]*channeldb.ChannelCloseSummary, error) {
			return []*channeldb.ChannelCloseSummary{}, nil
		},
		FetchClosedChannel: func(chanID *wire.OutPoint) (
			*channeldb.ChannelCloseSummary, error) {
			return &channeldb.ChannelCloseSummary{
				CloseHeight: 0,
			}, nil
		},
		Store:      storeIntercepter,
		ChainIO:    chainIO,
		SweepInput: sweeper.sweepInput,
		PublishTransaction: func(tx *wire.MsgTx, _ string) error {
			return publishFunc(tx, "nursery")
		},
	}

	nursery := newUtxoNursery(&nurseryCfg)
	nursery.Start()

	ctx := &nurseryTestContext{
		nursery:     nursery,
		notifier:    notifier,
		chainIO:     chainIO,
		store:       storeIntercepter,
		publishChan: publishChan,
		sweeper:     sweeper,
		timeoutChan: timeoutChan,
		t:           t,
		dbCleanup:   cleanup,
	}

	ctx.receiveTx = func() wire.MsgTx {
		var tx wire.MsgTx
		select {
		case tx = <-ctx.publishChan:
			utxnLog.Debugf("Published tx %v", tx.TxHash())
			return tx
		case <-time.After(defaultTestTimeout):
			pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)

			t.Fatalf("tx not published")
		}
		return tx
	}

	ctx.restart = func() bool {
		return checkStartStop(func() {
			utxnLog.Tracef("Restart sweeper and nursery")
			// Simulate lnd restart.
			ctx.nursery.Stop()

			// Restart sweeper.
			ctx.sweeper = newMockSweeper(t)

			/// Restart nursery.
			nurseryCfg.SweepInput = ctx.sweeper.sweepInput
			ctx.nursery = newUtxoNursery(&nurseryCfg)
			ctx.nursery.Start()

		})
	}

	// Start with testing an immediate restart.
	ctx.restart()

	return ctx
}

func (ctx *nurseryTestContext) notifyEpoch(height int32) {
	ctx.t.Helper()

	ctx.chainIO.bestHeight = height
	ctx.notifier.NotifyEpoch(height)
}

func (ctx *nurseryTestContext) finish() {
	defer ctx.dbCleanup()

	// Add a final restart point in this state
	ctx.restart()

	// We assume that when finish is called, nursery has finished all its
	// goroutines. This implies that the waitgroup is empty.
	signalChan := make(chan struct{})
	go func() {
		ctx.nursery.wg.Wait()
		close(signalChan)
	}()

	// The only goroutine that is still expected to be running is
	// incubator(). Simulate exit of this goroutine.
	ctx.nursery.wg.Done()

	// We now expect the Wait to succeed.
	select {
	case <-signalChan:
	case <-time.After(time.Second):
		ctx.t.Fatalf("lingering goroutines detected after test " +
			"is finished")
	}

	// Restore waitgroup state to what it was before.
	ctx.nursery.wg.Add(1)

	ctx.nursery.Stop()

	// We should have consumed and asserted all published transactions in
	// our unit tests.
	select {
	case <-ctx.publishChan:
		ctx.t.Fatalf("unexpected transactions published")
	default:
	}

	// Assert that the database is empty. All channels removed and height
	// index cleared.
	nurseryChannels, err := ctx.nursery.cfg.Store.ListChannels()
	if err != nil {
		ctx.t.Fatal(err)
	}
	if len(nurseryChannels) > 0 {
		ctx.t.Fatalf("Expected all channels to be removed from store")
	}

	activeHeights, err := ctx.nursery.cfg.Store.HeightsBelowOrEqual(
		math.MaxUint32)
	if err != nil {
		ctx.t.Fatal(err)
	}
	if len(activeHeights) > 0 {
		ctx.t.Fatalf("Expected height index to be empty")
	}
}

func createOutgoingRes(onLocalCommitment bool) *lnwallet.OutgoingHtlcResolution {
	// Set up an outgoing htlc resolution to hand off to nursery.
	closeTx := &wire.MsgTx{}

	htlcOp := wire.OutPoint{
		Hash:  closeTx.TxHash(),
		Index: 0,
	}

	outgoingRes := lnwallet.OutgoingHtlcResolution{
		Expiry: 125,
		SweepSignDesc: input.SignDescriptor{
			Output: &wire.TxOut{
				Value: 10000,
			},
		},
	}

	if onLocalCommitment {
		timeoutTx := &wire.MsgTx{
			TxIn: []*wire.TxIn{
				{
					PreviousOutPoint: htlcOp,
					SignatureScript:  []byte{},
				},
			},
			TxOut: []*wire.TxOut{
				{},
			},
		}

		outgoingRes.SignedTimeoutTx = timeoutTx
		outgoingRes.CsvDelay = 2
	} else {
		outgoingRes.ClaimOutpoint = htlcOp
		outgoingRes.CsvDelay = 0
	}

	return &outgoingRes
}

func incubateTestOutput(t *testing.T, nursery *utxoNursery,
	onLocalCommitment bool) *lnwallet.OutgoingHtlcResolution {

	outgoingRes := createOutgoingRes(onLocalCommitment)

	// Hand off to nursery.
	err := nursery.IncubateOutputs(
		testChanPoint,
		[]lnwallet.OutgoingHtlcResolution{*outgoingRes},
		nil, 0,
	)
	if err != nil {
		t.Fatal(err)
	}

	// IncubateOutputs is executing synchronously and we expect the output
	// to immediately show up in the report.
	expectedStage := uint32(2)
	if onLocalCommitment {
		expectedStage = 1
	}
	assertNurseryReport(t, nursery, 1, expectedStage, 10000)

	return outgoingRes
}

func assertNurseryReport(t *testing.T, nursery *utxoNursery,
	expectedNofHtlcs int, expectedStage uint32,
	expectedLimboBalance dcrutil.Amount) {
	report, err := nursery.NurseryReport(&testChanPoint)
	if err != nil {
		t.Fatal(err)
	}

	if len(report.htlcs) != expectedNofHtlcs {
		t.Fatalf("expected %v outputs to be reported, but report "+
			"only contains %v", expectedNofHtlcs, len(report.htlcs))
	}

	if expectedNofHtlcs != 0 {
		htlcReport := report.htlcs[0]
		if htlcReport.stage != expectedStage {
			t.Fatalf("expected htlc be advanced to stage %v, but "+
				"it is reported in stage %v",
				expectedStage, htlcReport.stage)
		}
	}

	if report.limboBalance != expectedLimboBalance {
		t.Fatalf("expected limbo balance to be %v, but it is %v instead",
			expectedLimboBalance, report.limboBalance)
	}
}

func assertNurseryReportUnavailable(t *testing.T, nursery *utxoNursery) {
	_, err := nursery.NurseryReport(&testChanPoint)
	if err != ErrContractNotFound {
		t.Fatal("expected report to be unavailable")
	}
}

// testRestartLoop runs the specified test multiple times and in every run it
// will attempt to execute a restart action in a different location. This is to
// assert that the unit under test is recovering correctly from restarts.
func testRestartLoop(t *testing.T, test func(*testing.T,
	func(func()) bool)) {

	// Start with running the test without any restarts (index zero)
	restartIdx := 0

	for {
		currentStartStopIdx := 0

		// checkStartStop is called at every point in the test where a
		// restart should be exercised. When this function is called as
		// many times as the current value of currentStartStopIdx, it
		// will execute startStopFunc.
		checkStartStop := func(startStopFunc func()) bool {
			currentStartStopIdx++
			if restartIdx == currentStartStopIdx {
				startStopFunc()

				return true
			}
			utxnLog.Debugf("Skipping restart point %v",
				currentStartStopIdx)
			return false
		}

		var subTestName string
		if restartIdx == 0 {
			subTestName = "no_restart"
		} else {
			subTestName = fmt.Sprintf("restart_%v", restartIdx)
		}
		t.Run(subTestName,
			func(t *testing.T) {
				test(t, checkStartStop)
			})

		// Exit the loop when all restart points have been tested.
		if currentStartStopIdx == restartIdx {
			return
		}
		restartIdx++
	}
}

func TestNurseryOutgoingHtlcSuccessOnLocal(t *testing.T) {
	testRestartLoop(t, testNurseryOutgoingHtlcSuccessOnLocal)
}

func testNurseryOutgoingHtlcSuccessOnLocal(t *testing.T,
	checkStartStop func(func()) bool) {

	ctx := createNurseryTestContext(t, checkStartStop)

	outgoingRes := incubateTestOutput(t, ctx.nursery, true)

	ctx.restart()

	// Notify arrival of block where HTLC CLTV expires.
	ctx.notifyEpoch(125)

	// This should trigger nursery to publish the timeout tx.
	ctx.receiveTx()

	if ctx.restart() {
		// Restart should retrigger broadcast of timeout tx.
		ctx.receiveTx()
	}

	// Confirm the timeout tx. This should promote the HTLC to KNDR state.
	timeoutTxHash := outgoingRes.SignedTimeoutTx.TxHash()
	if err := ctx.notifier.ConfirmTx(&timeoutTxHash, 126); err != nil {
		t.Fatal(err)
	}

	// Wait for output to be promoted in store to KNDR.
	select {
	case <-ctx.store.cribToKinderChan:
	case <-time.After(defaultTestTimeout):
		t.Fatalf("output not promoted to KNDR")
	}

	ctx.restart()

	// Notify arrival of block where second level HTLC unlocks.
	ctx.notifyEpoch(128)

	// Check final sweep into wallet.
	testSweepHtlc(t, ctx)

	ctx.finish()
}

func TestNurseryOutgoingHtlcSuccessOnRemote(t *testing.T) {
	testRestartLoop(t, testNurseryOutgoingHtlcSuccessOnRemote)
}

func testNurseryOutgoingHtlcSuccessOnRemote(t *testing.T,
	checkStartStop func(func()) bool) {

	ctx := createNurseryTestContext(t, checkStartStop)

	outgoingRes := incubateTestOutput(t, ctx.nursery, false)

	ctx.restart()

	// Notify confirmation of the commitment tx. Is only listened to when
	// resolving remote commitment tx.
	//
	// TODO(joostjager): This is probably not correct?
	err := ctx.notifier.ConfirmTx(&outgoingRes.ClaimOutpoint.Hash, 124)
	if err != nil {
		t.Fatal(err)
	}

	// Wait for output to be promoted from PSCL to KNDR.
	select {
	case <-ctx.store.preschoolToKinderChan:
	case <-time.After(defaultTestTimeout):
		t.Fatalf("output not promoted to KNDR")
	}

	ctx.restart()

	// Notify arrival of block where HTLC CLTV expires.
	ctx.notifyEpoch(125)

	// Check final sweep into wallet.
	testSweepHtlc(t, ctx)

	ctx.finish()
}

func testSweepHtlc(t *testing.T, ctx *nurseryTestContext) {
	testSweep(t, ctx, func() {
		// Verify stage in nursery report. HTLCs should now both still
		// be in stage two.
		assertNurseryReport(t, ctx.nursery, 1, 2, 10000)
	})
}

func testSweep(t *testing.T, ctx *nurseryTestContext,
	afterPublishAssert func()) {

	// Wait for nursery to publish the sweep tx.
	ctx.sweeper.expectSweep()

	if ctx.restart() {
		// Nursery reoffers its input after a restart.
		ctx.sweeper.expectSweep()
	}

	afterPublishAssert()

	// Confirm the sweep tx.
	ctx.sweeper.sweepAll()

	// Wait for output to be promoted in store to GRAD.
	select {
	case <-ctx.store.graduateKinderChan:
	case <-time.After(defaultTestTimeout):
		pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)
		t.Fatalf("output not graduated")
	}

	ctx.restart()

	// As there only was one output to graduate, we expect the channel to be
	// closed and no report available anymore.
	assertNurseryReportUnavailable(t, ctx.nursery)
}

type nurseryStoreInterceptor struct {
	ns NurseryStore

	// TODO(joostjager): put more useful info through these channels.
	cribToKinderChan      chan struct{}
	cribToRemoteSpendChan chan struct{}
	graduateKinderChan    chan struct{}
	preschoolToKinderChan chan struct{}
}

func newNurseryStoreInterceptor(ns NurseryStore) *nurseryStoreInterceptor {
	return &nurseryStoreInterceptor{
		ns:                    ns,
		cribToKinderChan:      make(chan struct{}),
		cribToRemoteSpendChan: make(chan struct{}),
		graduateKinderChan:    make(chan struct{}),
		preschoolToKinderChan: make(chan struct{}),
	}
}

func (i *nurseryStoreInterceptor) Incubate(kidOutputs []kidOutput,
	babyOutputs []babyOutput) error {

	return i.ns.Incubate(kidOutputs, babyOutputs)
}

func (i *nurseryStoreInterceptor) CribToKinder(babyOutput *babyOutput) error {
	err := i.ns.CribToKinder(babyOutput)

	i.cribToKinderChan <- struct{}{}

	return err
}

func (i *nurseryStoreInterceptor) PreschoolToKinder(kidOutput *kidOutput,
	lastGradHeight uint32) error {

	err := i.ns.PreschoolToKinder(kidOutput, lastGradHeight)

	i.preschoolToKinderChan <- struct{}{}

	return err
}

func (i *nurseryStoreInterceptor) GraduateKinder(height uint32, kid *kidOutput) error {
	err := i.ns.GraduateKinder(height, kid)

	i.graduateKinderChan <- struct{}{}

	return err
}

func (i *nurseryStoreInterceptor) FetchPreschools() ([]kidOutput, error) {
	return i.ns.FetchPreschools()
}

func (i *nurseryStoreInterceptor) FetchClass(height uint32) (
	[]kidOutput, []babyOutput, error) {

	return i.ns.FetchClass(height)
}

func (i *nurseryStoreInterceptor) HeightsBelowOrEqual(height uint32) (
	[]uint32, error) {

	return i.ns.HeightsBelowOrEqual(height)
}

func (i *nurseryStoreInterceptor) ForChanOutputs(chanPoint *wire.OutPoint,
	callback func([]byte, []byte) error) error {

	return i.ns.ForChanOutputs(chanPoint, callback)
}

func (i *nurseryStoreInterceptor) ListChannels() ([]wire.OutPoint, error) {
	return i.ns.ListChannels()
}

func (i *nurseryStoreInterceptor) IsMatureChannel(chanPoint *wire.OutPoint) (
	bool, error) {

	return i.ns.IsMatureChannel(chanPoint)
}

func (i *nurseryStoreInterceptor) RemoveChannel(chanPoint *wire.OutPoint) error {
	return i.ns.RemoveChannel(chanPoint)
}

type mockSweeper struct {
	lock sync.Mutex

	resultChans map[wire.OutPoint]chan sweep.Result
	t           *testing.T

	sweepChan chan input.Input
}

func newMockSweeper(t *testing.T) *mockSweeper {
	return &mockSweeper{
		resultChans: make(map[wire.OutPoint]chan sweep.Result),
		sweepChan:   make(chan input.Input, 1),
		t:           t,
	}
}

func (s *mockSweeper) sweepInput(input input.Input,
	_ sweep.Params) (chan sweep.Result, error) {

	utxnLog.Debugf("mockSweeper sweepInput called for %v", *input.OutPoint())

	select {
	case s.sweepChan <- input:
	case <-time.After(defaultTestTimeout):
		s.t.Fatal("signal result timeout")
	}

	s.lock.Lock()
	defer s.lock.Unlock()

	c := make(chan sweep.Result, 1)
	s.resultChans[*input.OutPoint()] = c

	return c, nil
}

func (s *mockSweeper) expectSweep() {
	s.t.Helper()

	select {
	case <-s.sweepChan:
	case <-time.After(defaultTestTimeout):
		s.t.Fatal("signal result timeout")
	}
}

func (s *mockSweeper) sweepAll() {
	s.t.Helper()

	s.lock.Lock()
	currentChans := s.resultChans
	s.resultChans = make(map[wire.OutPoint]chan sweep.Result)
	s.lock.Unlock()

	for o, c := range currentChans {
		utxnLog.Debugf("mockSweeper signal swept for %v", o)

		select {
		case c <- sweep.Result{}:
		case <-time.After(defaultTestTimeout):
			s.t.Fatal("signal result timeout")
		}
	}
}