Simulation: simulate ABCIApp state machine

[cwgoes]

Write simple Tendermint simulation code to collate transactions, propose blocks, and execute the multi-connection ABCIApp state machine just like Tendermint does. Include the full range of possible relevant states (e.g. transactions failing checktx still sent to delivertx, gas limits exceeded, transactions reordered from mempool order).

This should be in addition to, not instead of, direct-msg simulation (what we have presently), because it will be slower, but this will help us catch issues like #2772.

cc @ValarDragon

[cwgoes]

We could still do this; do you think it would be useful @rigelrozanski or should this be closed?

[rigelrozanski]

I don't fully grasp why this is useful. Is it to catch unanticipated possible behaviours of tendermint?

transactions failing checktx still sent to delivertx

Is this possible to occur? malicious validator?

[cwgoes]

Is this possible to occur? malicious validator?

Yes; the proposer can do this, for example.

[rigelrozanski]

Okay then yes - I see this as a useful feature worth developing. However doesn't seem pressing

• Ideally I'd like to see this type of testing infrastructure provided within tendermint (so it can be easily maintained as tendermint changes).