test: implement MinRelayFee RPC

test/lnd_services_mock.go

@@ -29,6 +29,7 @@ func NewMockLnd() *LndMockServices {
 	lightningClient := &mockLightningClient{}
 	walletKit := &mockWalletKit{
 		feeEstimates: make(map[int32]chainfee.SatPerKWeight),
+		minRelayFee:  chainfee.FeePerKwFloor,
 	}
 	chainNotifier := &mockChainNotifier{}
 	signer := &mockSigner{}
@@ -278,3 +279,7 @@ func (s *LndMockServices) SetFeeEstimate(confTarget int32,
 		confTarget, feeEstimate,
 	)
 }
+
+func (s *LndMockServices) SetMinRelayFee(feeEstimate chainfee.SatPerKWeight) {
+	s.LndServices.WalletKit.(*mockWalletKit).setMinRelayFee(feeEstimate)
+}

test/walletkit_mock.go

@@ -34,6 +34,7 @@ type mockWalletKit struct {
 
 	feeEstimateLock sync.Mutex
 	feeEstimates    map[int32]chainfee.SatPerKWeight
+	minRelayFee     chainfee.SatPerKWeight
 }
 
 var _ lndclient.WalletKitClient = (*mockWalletKit)(nil)
@@ -169,6 +170,24 @@ func (m *mockWalletKit) EstimateFeeRate(ctx context.Context,
 	return feeEstimate, nil
 }
 
+func (m *mockWalletKit) setMinRelayFee(fee chainfee.SatPerKWeight) {
+	m.feeEstimateLock.Lock()
+	defer m.feeEstimateLock.Unlock()
+
+	m.minRelayFee = fee
+}
+
+// MinRelayFee returns the current minimum relay fee based on our chain backend
+// in sat/kw. It can be set with setMinRelayFee.
+func (m *mockWalletKit) MinRelayFee(
+	ctx context.Context) (chainfee.SatPerKWeight, error) {
+
+	m.feeEstimateLock.Lock()
+	defer m.feeEstimateLock.Unlock()
+
+	return m.minRelayFee, nil
+}
+
 // ListSweeps returns a list of the sweep transaction ids known to our node.
 func (m *mockWalletKit) ListSweeps(_ context.Context, _ int32) (
 	[]string, error) {