Setup a Local Testnet

This guide describes how to set up a local mini-testnet using erdpy. The purpose of a local mini-testnet is to allow developers to experiment with and test their Smart Contracts, in addition to writing unit and integration tests.

The mini-testnet contains:

  • Validator Nodes (two, by default)
  • Observer Nodes (two, by default)
  • A Seednode
  • An Elrond Proxy

If not specified otherwise, the mini-testnet starts with one Shard plus the Metachain (each with one Validator and one Observer).

Prerequisites: erdpy

In order to install erdpy, follow the instructions at install erdpy.

erdpy version

Make sure your erdpy version is 1.3.2 or higher.

Prerequisites: Node and Proxy

Run the following command, which will fetch the prerequisites (elrond-go, elrond-proxy-go, golang and testwallets) into ~/elrondsdk:

$ erdpy testnet prerequisites

Testnet Configuration

Let's configure the following network parameters in erdpy, so that subsequent command invocations (of erdpy) will not require you explicitly provide the --proxy and --chainID arguments:

$ erdpy config set chainID local-testnet
$ erdpy config set proxy http://localhost:7950

Then, in a folder of your choice add a file names testnet.toml with the content below.

$ mkdir MySandbox && cd MySandbox
$ touch testnet.toml

testnet.toml
[networking]
port_proxy = 7950
tip

erdpy allows you to customize the configuration of the local mini-testnet in much greater detail, but for the sake of simplicity, in the example above we've only set the TCP port of the Elrond Proxy.

Then, configure and build the local testnet as follows:

$ cd MySandbox
$ erdpy testnet config

Upon running this command, a new folder called testnet will be added in the current directory. This folder contains the Node & Proxy binaries, their configurations, plus the development wallets.

warning

The development wallets (Alice, Bob, Carol, ..., Mike) are publicly known - they should only be used for development and testing purpose.

The development wallets are minted at genesis and their keys (both PEM files and Wallet JSON files) can be found in the folder testnet/wallets/users.

Starting the Testnet

erdpy testnet start

This will start the Seednode, the Validators, the Observers and the Proxy.

important

Note that the Proxy starts with a delay of about 30 seconds.

Sending transactions

Let's send a simple transaction using erdpy:

Simple Transfer
erdpy tx new --recall-nonce --data="Hello, World" --gas-limit=70000 \
 --receiver=erd1spyavw0956vq68xj8y4tenjpq2wd5a9p2c6j8gsz7ztyrnpxrruqzu66jx \
 --pem=~/elrondsdk/testwallets/latest/users/alice.pem \
 --send

You should see the prepared transaction and the transaction hash in the stdout (or in the --outfile of your choice). Using the transaction hash, you can query the status of the transaction against the Proxy or against erdpy itself:

$ curl http://localhost:7950/transaction/1dcfb2227e32483f0a5148b98341af319e9bd2824a76f605421482b36a1418f7
$ erdpy tx get --hash=1dcfb2227e32483f0a5148b98341af319e9bd2824a76f605421482b36a1418f7

Deploying and interacting with Smart Contracts

Let's deploy a Smart Contract using erdpy. We'll use the simple Counter as an example.

If you need guidance on how to build the Counter sample contract, please follow the Counter SmartContract Tutorial.

Deploy Contract
erdpy --verbose contract deploy --bytecode=./counter.wasm \
 --recall-nonce --gas-limit=5000000 \
 --pem=~/elrondsdk/testwallets/latest/users/alice.pem \
 --outfile=myCounter.json \
 --send

Upon deployment, you can check the status of the transaction and the existence of the Smart Contract:

$ curl http://localhost:7950/transaction/0db61bab8e78779ae009300988c6be0949086d93e2b7adfddd5e6375a4b6eeb7 | jq
$ curl http://localhost:7950/address/erd1qqqqqqqqqqqqqpgqj5zftf3ef3gqm3gklcetpmxwg43rh8z2d8ss2e49aq | jq

If everything is fine (transaction status is executed and the code property of the address is set), you can interact with or perform queries against the deployed contract:

Call Contract
erdpy --verbose contract call erd1qqqqqqqqqqqqqpgqj5zftf3ef3gqm3gklcetpmxwg43rh8z2d8ss2e49aq \
 --recall-nonce --gas-limit=1000000 --function=increment \
 --pem=~/elrondsdk/testwallets/latest/users/alice.pem --outfile=myCall.json \
 --send


Query Contract
erdpy --verbose contract query erd1qqqqqqqqqqqqqpgqj5zftf3ef3gqm3gklcetpmxwg43rh8z2d8ss2e49aq --function=get

Simulating transactions

At times, you can simulate transactions instead of broadcasting them, by replacing the flag --send with the flag --simulate. For example:

Simulate: Call Contract
all-nonce --gas-limit=1000000 --function=increment \
 --pem=~/elrondsdk/testwallets/latest/users/alice.pem --outfile=myCall.json \
 --simulate

Simulate: Simple Transfer
erdpy tx new --recall-nonce --data="Hello, World" --gas-limit=70000 \
 --receiver=erd1spyavw0956vq68xj8y4tenjpq2wd5a9p2c6j8gsz7ztyrnpxrruqzu66jx \
 --pem=~/elrondsdk/testwallets/latest/users/alice.pem \
 --simulate
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