EVM

A Python wrapper around an Embedded Rust based Ethereum Virtual Machine.

Constructor 

class PyEvm: Create and return an instance of the EVM that uses an in-memory database.

Example:

>>> from simular import PyEvm
>>> evm = PyEvm()

Methods 

static PyEvm.from_fork(url: str, blocknumber: int = None)

Create and return an instance of the EVM that will pull state from a remote Ethereum node.

Parameters:

url – the url (https://...) to a remote Ethereum node with JSON-RPC support
blocknumber – (optional) the specific blocknumber to pull state at. If None, the latest block will be used.

Returns:

an instance of the EVM

Example:

>>> from simular import PyEvm
>>> evm = PyEvm.from_fork('http://...', blocknumber=195653)

static PyEvm.from_snapshot(snapshot: str)

Create and return an instance of the EVM from a previously created snapshot. See create_snapshot below.

Parameters:: snapshot – a (str) serialized snapshot
Returns:: an instance of the EVM

Example:

Assume hello_snap.json is a file from a saved snapshot.

>>> from simular import PyEvm

# load the json file
>>> with open('hello_snap.json') as f:
...     snap = f.read()
>>> evm = PyEvm.from_snapshot(snap)

create_snapshot()

Create a JSON formatted snapshot of the current state of the EVM.

Returns:: (str) the serialized state

Example:

>>> evm = PyEvm()

# do stuff with the EVM

>>> snap = evm.create_snapshot()

create_account(address: str, balance=None)

Create an account

Note

See utils.create_account

Parameters:

address – (str) a valid, hex-encoded Ethereum address
balance – (int) and optional balance in wei to set for the account. If None, balance = 0

get_balance(address: str)

Get the balance of the given address

Parameters:: address – (str) a valid, hex-encoded Ethereum address
Returns:: the balance in wei

transfer(caller: str, to: str, amount: int)

Transfer amount in wei from caller -> to

Parameters:

caller – (str) a valid, hex-encoded Ethereum address
to – (str) a valid, hex-encoded Ethereum address
amount – (int) the amount to transfer

Warning

This will fail if the caller does not have a sufficient balance to transfer

Example:

>>> from similar import PyEvm, create_account

>>> evm = PyEvm()

# create an account for Bob with 1 Ether
>>> bob = create_account(evm, value=int(1e18))

# create an account for Alice with no balance
>>> alice = create_account(evm)

# transfer 1 Ether from Bob to Alice
>>> evm.transfer(bob, alice, int(1e18))

# check Alice's balance
>>> evm.get_balance(alice)
1000000000000000000

advance_block(interval=None)

This method provides the ability to simulate the mining of blocks. It will advance block.number and block.timestamp.

It’s not necessary to call this method. However, some contracts may have logic that need this information.

Parameters:: interval – (int) optional. set the time in seconds between blocks. Default is 12 seconds

Example:

>>> evm.advance_block()

EVM

Constructor

Methods

Constructor 

Methods 