Add ERC20MintableBurnable test

[yudetamago]

Translate erc20_test_1.py ( https://github.com/ethereum/vyper/blob/97ed5fec89947d41fd91f5190c4478ffcadbb9fb/tests/examples/tokens/ERC20_solidity_compatible/test/erc20_tests_1.py ) to pytest

• convert
  • deposit to mint
  • withdraw to burn
• remove checking wei balance like self.assertEqual(initial_a1_balance - self.s.head_state.get_balance(self.t.a1), 2) because mint and burn are irrelevant to wei
• add tests about msg.sender == self.minter and to _to != ZERO_ADDRESS (L58-64)
• remove test_payability because there are no payable functions in ERC20MintableBurnable
• remove emitting no event assertions in test_raw_logs because checking events with call operation or failed tx may not be supported in eth_tester?
• remove tests about overflow (test_maxInts, test_bad_transfer, test_bad_deposit, and test_bad_transferFrom) because overflow assertion is supported by default in vyper
• remove test_failed_send_in_withdraw because it tests solidity code?

[nrryuya]

remove test_failed_send_in_withdraw because it tests solidity code?

I think the solidity contract is there to call the Vyper contract as an external contract.

[yudetamago]

I think the solidity contract is there to call the Vyper contract as an external contract.

ah, I got it.

[nrryuya]

remove emitting no event assertions in test_raw_logs because checking events with call operation or failed tx may not be supported in py-evm?

py-evm is not used in our repo, is it? I think event is not emitted when EVM reverts?

[yudetamago]

py-evm is not used in our repo, is it?

Ah, I misunderstood, eth_tester is used. (EDITED)

I think event is not emitted in revert?

Right, the original tests check it. https://github.com/ethereum/vyper/blob/97ed5fec89947d41fd91f5190c4478ffcadbb9fb/tests/examples/tokens/ERC20_solidity_compatible/test/erc20_tests_1.py#L272-L280 EDITED: My question is that there is something corresponding to this in eth_tester?

[nrryuya]

remove tests about overflow (test_maxInts, test_bad_transfer, test_bad_deposit, and test_bad_transferFrom) because overflow assertion is supported by default in vyper

I think they are necessary to check all the corner cases. If we have a variable X whose range is from A to B, we need to test with A and B for "complete testing". The statement that the tx fail in overflows is the implicit specification so we need to check it.

BTW,tThe issue below was fixed in Vyper compiler so we can mint MAX_UINT256. https://github.com/ethereum/vyper/blob/97ed5fec89947d41fd91f5190c4478ffcadbb9fb/tests/examples/tokens/ERC20_solidity_compatible/test/erc20_tests_1.py#L175

[nrryuya]

The statement that the tx fail in overflows is the implicit specification so we need to check it.

This isn't limited to overflow because any type has range. e.g. This code causes revert.

    a: int128 = MAX_INT128 - 1
    a += 2

[nrryuya]

I don't know why it's in the original but test for Solidity ERC20 can be omitted? https://github.com/ethereum/vyper/blob/97ed5fec89947d41fd91f5190c4478ffcadbb9fb/tests/examples/tokens/ERC20_solidity_compatible/test/erc20_tests_1.py#L393

[nrryuya]

~All what remains are the "bad_code" test. I'll work on this.~

EDIT: Done in #51

[yudetamago]

yeah!