How to create test accounts with custom balance programatically in web3.py?

Question

I am trying to write tests for a smart contract and am having trouble transferring funds to the contract's address.

I'm using web3.py app which (if I understand correctly) runs its own TestRPC, like this:

w3 = Web3(TestRPCProvider())

Then I deploy contract, after which I try to send funds to it:

ACCT_PASSPHRASE = 'KEYSMASH FJAFJKLDSKF7JKFDJ 1530'
acct_addr = w3.personal.newAccount(ACCT_PASSPHRASE)
w3.personal.unlockAccount(acct_addr, ACCT_PASSPHRASE, 1000)
txn_hash = w3.eth.sendTransaction(transaction={
    "from": acct_addr,
    "to": crowdsale_contract_address,
    "value": 5,
    "gas": 3000000,
})
txn = w3.eth.getTransaction(txn_hash)

Result is of course an exception:

ethereum.exceptions.InsufficientBalance: <Transaction(b'30c4')>: 'balance' actual:0 target:3000005

So, how do I create an account with sufficient balance?

Alternatively, how do I use one of the preexisting accounts? What are their passwords? Do they have any balance?

Answer 1

Alternatively, how do I use one of the preexisting accounts? What are their passwords? Do they have any balance?

TestRPC includes accounts with pre-existing balances in w3.eth.accounts. They are unlocked, so you don't need a password,

Alternatively, you can set the gasPrice to 0, and invoke contracts from an unfunded account.

Answer 2

I solved it by using external TestRPC (Ganache really) installation and using HTTPProvider to interact with it.