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Chains and blocks#

For single chain tests, Wake provides the global default_chain variable. This variable is a Chain object that can be used to change the chain parameters or access the chain data. Other Chain instances can be created, which is useful in Cross-chain testing.

Chain properties#

The Chain object has the following properties:

Property Description
accounts list of Account objects owned by the client (private keys are known to the client)
automine whether to automatically mine blocks
blocks property to access the chain blocks
block_gas_limit gas limit of the pending block
chain_id chain ID
chain_interface low-level chain interface useful for debugging and power users
client_version client version as reported by the web3_clientVersion JSON-RPC method
coinbase coinbase Account, i.e. account of the miner who mined the block
connected whether the chain is connected
default_access_list_account default Account used for access list creation requests
default_call_account default Account used for calls
default_estimate_account default Account used for gas estimations
default_tx_account default Account used for transactions
default_tx_confirmations default number of confirmations (mined blocks) needed before a transaction object is returned
default_tx_type default transaction type (0, 1, or 2) used when sending transactions
gas_price gas price used for all type 0 and type 1 transactions sent to the chain
max_priority_fee_per_gas max priority fee per gas used for all type 2 transactions sent to the chain
require_signed_transactions whether to send signed transactions or unsigned transactions
txs dictionary of transaction objects indexed by transaction hash (a string starting with 0x)
tx_callback callback function to be called when a transaction is mined; applies only to return_tx=False transactions

automine, block_gas_limit, coinbase, default_call_account, default_tx_account, gas_price, and tx_callback can be assigned to.

Chain methods#

The Chain object has the following methods:

Method Description
change_automine context manager to temporarily change the automine property
connect context manager to launch a chain and connect to it or connect to an already running chain
mine mine a block with an optional callback function to set the next block timestamp
mine_many mine multiple blocks with an optional timestamp delta between blocks
reset reset the chain to its initial state
revert revert the chain to a previous state given by a snapshot ID
set_default_accounts set the default accounts for tx, call, estimate, and access_list requests at once
set_min_gas_price set the minimum gas price accepted by the chain
set_next_block_base_fee_per_gas set the base fee per gas for the next block
set_next_block_timestamp set the timestamp of the next block
snapshot take a snapshot of the chain state; return a snapshot ID
snapshot_and_revert context manager to take a snapshot and revert to it after the context ends
update_accounts update the accounts list
deploy low-level method for deploying contracts from creation code

It is recommended to use the context managers change_automine and snapshot_and_revert instead of setting the automine property directly or calling snapshot and revert manually.

The following example presents the use of Chain methods:

from wake.testing import default_chain

def test_chain():
    # launch a chain and connect to it
    with default_chain.connect(), default_chain.snapshot_and_revert():
        # mine a block with the timestamp 1 greater than the previous block
        default_chain.mine(lambda x: x + 1)

All Chain context managers can be used as decorators:

from wake.testing import default_chain

def test_chain():
    # mine a block with the timestamp 1 greater than the previous block
    default_chain.mine(lambda x: x + 1)

connect keyword arguments#

The connect context manager accepts keyword arguments that can override the command line arguments set in configuration files:

Keyword argument Description Default value
accounts number of accounts to generate None (do not override)
chain_id chain ID assigned to the chain None (do not override)
fork URL of the chain to fork from None (do not override)
hardfork hardfork to use None (do not override)
min_gas_price minimum gas price accepted by the chain 0
block_base_fee_per_gas base fee per gas for the next block 0


connect keyword arguments can only be used when launching a new development chain. Also, it is not possible to set these keyword arguments when working with Hardhat.

from wake.testing import default_chain

def test_chain():
    assert len(default_chain.accounts) == 15
    assert default_chain.chain_id == 1020

Accessing chain blocks#

The chain.blocks property can be used to access up-to-date chain blocks data. It can be indexed by an integer or string literals latest, pending, earliest, safe, and finalized:

from wake.testing import default_chain
from pytypes.contracts.Counter import Counter

def test_chain_blocks():

    # get the block 0
    block0 = default_chain.blocks[0]
    # block 0 and earliest are the same
    assert block0 == default_chain.blocks["earliest"]

    counter = Counter.deploy()

    # find the first block with non-zero transactions count
    block = next(block for block in default_chain.blocks if len(block.txs) > 0)

    assert block.txs[0].return_value == counter

    with default_chain.change_automine(False):
        # block -1 and latest are the same
        assert default_chain.blocks[-1] == default_chain.blocks["latest"]

        tx = counter.increment(confirmations=0)

        # pending block contains the transaction
        assert tx in default_chain.blocks["pending"].txs

Block properties#

The following table lists the most important block properties:

Property Description
chain chain the block belongs to
hash block hash
number block number
parent_hash parent block hash
miner miner Account of the block
gas_used amount of gas used in the block
gas_limit block gas limit
timestamp block timestamp
txs list of transaction objects in the block sorted by transaction index