refactor: remove btc deposit fee v1 and improve unit tests (#2899)

* remove CalcDepositorFeeV2; add unit tests; migration mock btc client to Mockery

* replace manual btc rpc mock with Mockery

* move createRPCClientAndLoadTx to testutils package as CreateBTCRPCAndLoadTx

* move GetSenderAddressByVin to inbound.go as it's for inbound observation

* add unit test for IsBlockConfirmed

* add changelog entry

* remove unused constants

* move changelog entry under Refactor section; created sub method DecodeSenderFromScript() and added unit tests

changelog.md

@@ -19,6 +19,7 @@
 * [2802](https://github.com/zeta-chain/node/pull/2802) - set default liquidity cap for new ZRC20s
 * [2826](https://github.com/zeta-chain/node/pull/2826) - remove unused code from emissions module and add new parameter for fixed block reward amount
 * [2890](https://github.com/zeta-chain/node/pull/2890) - refactor `MsgUpdateChainInfo` to accept a single chain, and add `MsgRemoveChainInfo` to remove a chain
+* [2899](https://github.com/zeta-chain/node/pull/2899) - remove btc deposit fee v1 and improve unit tests
 
 ### Tests
 

e2e/runner/bitcoin.go

@@ -267,15 +267,13 @@ func (r *E2ERunner) SendToTSSFromDeployerWithMemo(
 	rawtx, err := btcRPC.GetRawTransactionVerbose(txid)
 	require.NoError(r, err)
 
-	depositorFee := zetabitcoin.DefaultDepositorFee
 	events, err := btcobserver.FilterAndParseIncomingTx(
 		btcRPC,
 		[]btcjson.TxRawResult{*rawtx},
 		0,
 		r.BTCTSSAddress.EncodeAddress(),
 		log.Logger,
 		r.BitcoinParams,
-		depositorFee,
 	)
 	require.NoError(r, err)
 	r.Logger.Info("bitcoin inbound events:")

zetaclient/chains/base/observer.go

@@ -228,6 +228,15 @@ func (ob *Observer) WithLastBlock(lastBlock uint64) *Observer {
 	return ob
 }
 
+// IsBlockConfirmed checks if the given block number is confirmed.
+//
+// Note: block 100 is confirmed if the last block is 100 and confirmation count is 1.
+func (ob *Observer) IsBlockConfirmed(blockNumber uint64) bool {
+	lastBlock := ob.LastBlock()
+	confBlock := blockNumber + ob.chainParams.ConfirmationCount - 1
+	return lastBlock >= confBlock
+}
+
 // LastBlockScanned get last block scanned (not necessarily caught up with the chain; could be slow/paused).
 func (ob *Observer) LastBlockScanned() uint64 {
 	height := atomic.LoadUint64(&ob.lastBlockScanned)

zetaclient/chains/base/observer_test.go

@@ -27,12 +27,16 @@ import (
 const (
 	// defaultAlertLatency is the default alert latency (in seconds) for unit tests
 	defaultAlertLatency = 60
+
+	// defaultConfirmationCount is the default confirmation count for unit tests
+	defaultConfirmationCount = 2
 )
 
 // createObserver creates a new observer for testing
 func createObserver(t *testing.T, chain chains.Chain, alertLatency int64) *base.Observer {
 	// constructor parameters
 	chainParams := *sample.ChainParams(chain.ChainId)
+	chainParams.ConfirmationCount = defaultConfirmationCount
 	zetacoreClient := mocks.NewZetacoreClient(t)
 	tss := mocks.NewTSSMainnet()
 
@@ -267,6 +271,51 @@ func TestObserverGetterAndSetter(t *testing.T) {
 	})
 }
 
+func TestIsBlockConfirmed(t *testing.T) {
+	tests := []struct {
+		name      string
+		chain     chains.Chain
+		block     uint64
+		lastBlock uint64
+		confirmed bool
+	}{
+		{
+			name:      "should confirm block 100 when confirmation arrives 2",
+			chain:     chains.BitcoinMainnet,
+			block:     100,
+			lastBlock: 101, // got 2 confirmations
+			confirmed: true,
+		},
+		{
+			name:      "should not confirm block 100 when confirmation < 2",
+			chain:     chains.BitcoinMainnet,
+			block:     100,
+			lastBlock: 100, // got 1 confirmation, need one more
+			confirmed: false,
+		},
+		{
+			name:      "should confirm block 100 when confirmation arrives 2",
+			chain:     chains.Ethereum,
+			block:     100,
+			lastBlock: 99, // last block lagging behind, need to wait
+			confirmed: false,
+		},
+	}
+
+	// run tests
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// create observer
+			ob := createObserver(t, tt.chain, defaultAlertLatency)
+			ob = ob.WithLastBlock(tt.lastBlock)
+
+			// check if block is confirmed
+			confirmed := ob.IsBlockConfirmed(tt.block)
+			require.Equal(t, tt.confirmed, confirmed)
+		})
+	}
+}
+
 func TestOutboundID(t *testing.T) {
 	tests := []struct {
 		name  string

zetaclient/chains/bitcoin/fee.go

@@ -12,7 +12,6 @@ import (
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/pkg/errors"
-	"github.com/rs/zerolog"
 
 	"github.com/zeta-chain/node/pkg/chains"
 	"github.com/zeta-chain/node/zetaclient/chains/bitcoin/rpc"
@@ -44,13 +43,6 @@ const (
 
 	// feeRateCountBackBlocks is the default number of blocks to look back for fee rate estimation
 	feeRateCountBackBlocks = 2
-
-	// DynamicDepositorFeeHeight is the mainnet height from which dynamic depositor fee V1 is applied
-	DynamicDepositorFeeHeight = 834500
-
-	// DynamicDepositorFeeHeightV2 is the mainnet height from which dynamic depositor fee V2 is applied
-	// Height 863400 is approximately a month away (2024-09-28) from the time of writing, allowing enough time for the upgrade
-	DynamicDepositorFeeHeightV2 = 863400
 )
 
 var (
@@ -226,37 +218,8 @@ func CalcBlockAvgFeeRate(blockVb *btcjson.GetBlockVerboseTxResult, netParams *ch
 	return txsFees / int64(vBytes), nil
 }
 
-// CalcDepositorFee calculates the depositor fee for a given block
+// CalcDepositorFee calculates the depositor fee for a given tx result
 func CalcDepositorFee(
-	blockVb *btcjson.GetBlockVerboseTxResult,
-	chainID int64,
-	netParams *chaincfg.Params,
-	logger zerolog.Logger,
-) float64 {
-	// use default fee for regnet
-	if chains.IsBitcoinRegnet(chainID) {
-		return DefaultDepositorFee
-	}
-	// mainnet dynamic fee takes effect only after a planned upgrade height
-	if chains.IsBitcoinMainnet(chainID) && blockVb.Height < DynamicDepositorFeeHeight {
-		return DefaultDepositorFee
-	}
-
-	// calculate deposit fee rate
-	feeRate, err := CalcBlockAvgFeeRate(blockVb, netParams)
-	if err != nil {
-		feeRate = defaultDepositorFeeRate // use default fee rate if calculation fails, should not happen
-		logger.Error().Err(err).Msgf("cannot calculate fee rate for block %d", blockVb.Height)
-	}
-
-	// #nosec G115 always in range
-	feeRate = int64(float64(feeRate) * clientcommon.BTCOutboundGasPriceMultiplier)
-
-	return DepositorFee(feeRate)
-}
-
-// CalcDepositorFeeV2 calculates the depositor fee for a given tx result
-func CalcDepositorFeeV2(
 	rpcClient interfaces.BTCRPCClient,
 	rawResult *btcjson.TxRawResult,
 	netParams *chaincfg.Params,