Require constant, view, and pure methods be invoked by `.call`

With 0.3.5 we’ve begun using a testrpc that implements the Byzantium fork. Unfortunately we’re also pushing up against the limits of solidity-coverage’s current design and there were some new bugs discovered while doing the upgrade:

• highest working pragma is 0.4.18. Above that you will get compilation errors complaining that the non-state-changing nature of constant and view methods has been violated.
• pure modifier compiles but returns a transaction object rather than a value. If your tests check / use that value they will fail.

[area]

The branch fix/callNotRequired contains my swing at fixing this ‘properly’. During the original parsing of the contracts done to get the source mapping, we record which functions are marked as constant, pure, or view. We then compile the contracts with all of those modifiers stripped, as before, and set the constant parameter in the ABI to true for the functions we recorded as constant.

Two tests fail to pass on that branch, and I can’t spot why. I’m hoping @cgewecke can come to my rescue, there. They are

  1) app config with test command options string: should run test
  2) app config racing test command: should run test after testrpc has started

They appear to time out.

Other issues with the branch that should be discussed:

• This integrates us even more closely with Truffle. I have included a compileCommand option, but it looks for the JSON files corresponding to the contracts in the ./build/contracts/ directory, which is obviously Truffle specific. Even potentially more problematic, the JSON files generated by truffle are do not contain just the ABI, but the abi is just one property in the object. Do we know of anyone using solidity-coverage without truffle?
• Other related properties in the ABI are ignored currently, specifically payable and stateMutability. We should change these too to guard against changes to Truffle’s behavior in the future, but I’m unsure currently what the valid combinations are. The Solidity Documentation has what we need, though.

I have not opened a PR yet, but if you want to move discussion there, I’m happy to do that too.

[frangio]

@cgewecke We’re actually about to upgrade to the latest Truffle with Solidity 0.4.18. We’re considering removing coverage temporarily (OpenZeppelin/zeppelin-solidity#573), but 4 weeks until it’s fixed might be too long. 😕