Using Python’s grpcio and unittest.mock , you can create a fake LND server in under 50 lines. import grpc from unittest.mock import MagicMock import lnd_pb2 # Generated from LND proto files class MockLNDServer: def init (self): self.invoices = {}
Introduction: Why Emulate LND? In the rapidly evolving world of Bitcoin’s Layer 2 scaling solution, the Lightning Network Daemon (LND) stands as one of the most popular implementations. However, developing, testing, and debugging applications on a live mainnet is dangerous. Making a mistake with real satoshis can lead to financial loss or, worse, the permanent loss of a payment channel. lnd emulator utility work
Enter the concept of . This phrase refers to the collection of tools, scripts, and methodologies used to simulate an LND node in a controlled, fake environment. An emulator mimics the behavior of a real LND node (gRPC calls, invoice generation, channel management) without touching the actual blockchain. Using Python’s grpcio and unittest
Creating a 10-node ring topology to test MPP (Multi-Path Payments) in zero real-world time. 3.3. regtest + btcd (The Blockchain Emulator) While not strictly "LND" emulation, running LND on Bitcoin’s RegTest (regression test mode) mode is the most authentic form of emulation. RegTest allows you to generate blocks instantly via RPC. Tools like bitcoind in RegTest act as the blockchain emulator, while LND runs as a real binary—but on a fake chain. This phrase refers to the collection of tools,
Simulating a "failure to find route" error to see how your wallet GUI reacts. 3.2. Polar (Lightning Labs’ GUI Emulator) Polar is a desktop application (Windows, Mac, Linux) that uses Docker to spin up entire fake Lightning networks. It is not a pure code-level emulator but rather a network emulator . You can drag, drop, and connect LND, c-lightning, and Eclair nodes on a virtual graph.
Testing channel force-close recovery by generating 100 fake blocks instantly. 3.4. mockery & gomock for LND (Unit Test Level) For developers writing Go-based applications that interface with LND, mockery can auto-generate emulated LND clients. This is the deepest form of utility work, where you emulate the interface of LND without running any network stack at all.
def LookupInvoice(self, request, context): # Emulate expiry: If the invoice was "created" more than 2 seconds ago, fail. # (In a real emulator, you'd store timestamps) if request.r_hash in self.invoices: return lnd_pb2.Invoice(settled=False, state=lnd_pb2.Invoice.UNPAID) else: context.set_code(grpc.StatusCode.NOT_FOUND) return lnd_pb2.Invoice()