lntest: allow specifying min relay feerate in itest

lntest/fee_service.go

@@ -33,6 +33,9 @@ type WebFeeService interface {
 	// target.
 	SetFeeRate(feeRate chainfee.SatPerKWeight, conf uint32)
 
+	// SetMinRelayFeerate sets a min relay feerate.
+	SetMinRelayFeerate(fee chainfee.SatPerKVByte)
+
 	// Reset resets the fee rate map to the default value.
 	Reset()
 }
@@ -52,8 +55,9 @@ const (
 type FeeService struct {
 	*testing.T
 
-	feeRateMap map[uint32]uint32
-	url        string
+	feeRateMap      map[uint32]uint32
+	minRelayFeerate chainfee.SatPerKVByte
+	url             string
 
 	srv  *http.Server
 	wg   sync.WaitGroup
@@ -79,6 +83,7 @@ func NewFeeService(t *testing.T) *FeeService {
 	f.feeRateMap = map[uint32]uint32{
 		feeServiceTarget: DefaultFeeRateSatPerKw,
 	}
+	f.minRelayFeerate = chainfee.FeePerKwFloor.FeePerKVByte()
 
 	listenAddr := fmt.Sprintf(":%v", port)
 	mux := http.NewServeMux()
@@ -114,9 +119,12 @@ func (f *FeeService) handleRequest(w http.ResponseWriter, _ *http.Request) {
 
 	bytes, err := json.Marshal(
 		struct {
-			Fees map[uint32]uint32 `json:"fee_by_block_target"`
+			//nolint:lll
+			Fees            map[uint32]uint32     `json:"fee_by_block_target"`
+			MinRelayFeerate chainfee.SatPerKVByte `json:"min_relay_feerate"`
 		}{
-			Fees: f.feeRateMap,
+			Fees:            f.feeRateMap,
+			MinRelayFeerate: f.minRelayFeerate,
 		},
 	)
 	require.NoErrorf(f, err, "cannot serialize estimates")
@@ -143,6 +151,14 @@ func (f *FeeService) SetFeeRate(fee chainfee.SatPerKWeight, conf uint32) {
 	f.feeRateMap[conf] = uint32(fee.FeePerKVByte())
 }
 
+// SetMinRelayFeerate sets a min relay feerate.
+func (f *FeeService) SetMinRelayFeerate(fee chainfee.SatPerKVByte) {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	f.minRelayFeerate = fee
+}
+
 // Reset resets the fee rate map to the default value.
 func (f *FeeService) Reset() {
 	f.lock.Lock()

lntest/harness.go

@@ -858,6 +858,12 @@ func (h *HarnessTest) SetFeeEstimateWithConf(
 	h.feeService.SetFeeRate(fee, conf)
 }
 
+// SetMinRelayFeerate sets a min relay fee rate to be returned from fee
+// estimator.
+func (h *HarnessTest) SetMinRelayFeerate(fee chainfee.SatPerKVByte) {
+	h.feeService.SetMinRelayFeerate(fee)
+}
+
 // validateNodeState checks that the node doesn't have any uncleaned states
 // which will affect its following tests.
 func (h *HarnessTest) validateNodeState(hn *node.HarnessNode) error {