fixed error when accessing blocks by blocknumber using eth_tester

[MatthiasLohr]

What was wrong?

When accessing a block by its block number using eth_tester, e.g. 3, the following error occured:

Block number must be a positive integer or one of the strings 'latest', 'earliest', or 'pending'. Got: 0x3

How was it fixed?

With this pull request, the ethereum_tester_middleware is extended by typing instructions for eth_getBalance.

Cute Animal Picture

Too tired for searching for a cat picture. Meow.

[pipermerriam]

It would be nice to have a test added for this as well.

[carver]

For reference:

web3.py/web3/_utils/module_testing/eth_module.py

Lines 205 to 210 in 6258d2e

	def test_eth_getCode_with_block_identifier(
	self, web3: "Web3", emitter_contract: "Contract"
	) -> None:
	code = web3.eth.getCode(emitter_contract.address, block_identifier=web3.eth.blockNumber)
	assert isinstance(code, HexBytes)
	assert len(code) > 0

Something like that, but with balance. I'd try to go one step further and say that you can verify that the balances are different on different blocks.

Notice that coinbase has a balance at the latest block:

web3.py/web3/_utils/module_testing/eth_module.py

Lines 124 to 127 in 6258d2e

	balance = web3.eth.getBalance(coinbase)
	assert is_integer(balance)
	assert balance >= 0

It seems a good bet that that balance is lower at the genesis block. See if you can verify that in a test. I'd highly recommend reverting the implementation commit, then writing the test and confirming that it fails. (In tox -e py36-integration-ethtester)

[wolovim]

@carver the genesis balance vs. later balance idea is a no-go in at least one case:

(Pdb++) web3.eth.getBalance(coinbase)
1000000000000000000000000
(Pdb++) web3.eth.blockNumber
0

however, testing of Literal(0) is enough to demonstrate that without the fix, an error is thrown:

ValidationError: Block number must be a positive integer or one of the strings 'latest', 'earliest', or 'pending'.  Got: 0x0

[carver]

genesis balance vs. later balance idea is a no-go in at least one case:

Sure, you would need to mine a block before that idea would work.

[carver]

Yup, LGTM!