Ethereum CLL Contract Simulator

mids106

I have created a simulator of the Ethereum C-Like Language Contracts. The intention of this simulator is to help contract coders develop and test their work using test driven best practises and in full isolation, without the need to connect to the Ethereum Test Net.

Contracts from the whitepaper are slightly modified to make them Python syntax compatible and contained within a Contract class. Automated testing scenarios are also written in a Simulator DSL (similar to unit tests) which can run, inspect and verify the outcome of contract runs.

Source Code:
https://github.com/jorisbontje/cll-sim

Let me know what you think!
Joris Bontje / @mids106 / mids on IRC #ethereum


Example Run:

./run.py examples/subcurrency.py

This will execute several simulation scenarios on the Sub-Currency example from the Ethereum whitepaper.

Example Output

sim          INFO    RUN test_insufficient_fee: 
sim          WARNING Stopped: Insufficient basefee
sim          INFO    --------------------
sim          INFO    RUN test_creation: 
sim          DEBUG   Accessing storage 1000
subcurrency  INFO    Initializing storage for creator alice
sim          DEBUG   Setting storage alice to 1000000000000000000
sim          DEBUG   Setting storage 1000 to 1
sim          INFO    --------------------
sim          INFO    RUN test_alice_to_bob: 
sim          DEBUG   Accessing storage 1000
sim          DEBUG   Accessing storage alice
subcurrency  INFO    Transfering 1000 from alice to bob
sim          DEBUG   Accessing storage alice
sim          DEBUG   Setting storage alice to 999999999999999000
sim          DEBUG   Accessing storage bob
sim          DEBUG   Setting storage bob to 1000
sim          INFO    --------------------
sim          INFO    RUN test_bob_to_charlie_invalid: 
sim          DEBUG   Accessing storage 1000
sim          DEBUG   Accessing storage bob
sim          DEBUG   Accessing storage bob
sim          WARNING Stopped: Insufficient funds, bob has 1000 needs 1001
sim          INFO    --------------------
sim          INFO    RUN test_bob_to_charlie_valid: 
sim          DEBUG   Accessing storage 1000
sim          DEBUG   Accessing storage bob
subcurrency  INFO    Transfering 1000 from bob to charlie
sim          DEBUG   Accessing storage bob
sim          DEBUG   Setting storage bob to 0
sim          DEBUG   Accessing storage charlie
sim          DEBUG   Setting storage charlie to 1000
sim          INFO    --------------------
subcurrency  INFO    , {1000: 1, 'charlie': 1000, 'bob': 0, 'alice': 999999999999999000})>

onecorp

This is extremely cool! Awesome work, and such a fast turn around since you mentioned it on irc.

It'd be nice if there was a cleaner way to auto create the Contract class based directly on the cll

mids106

Short update:

James Levy contributed the simulation for the datafeed example. We have added `mktx` and `block.contract_storage` support which now also allows the financial derivative example to run. During the implementation I discovered a couple bugs in the whitepaper reference code, this emphasises that proper contract simulation is so essential to Ethereum.

Take a look at the contract with simulation runs:
https://github.com/jorisbontje/cll-sim/blob/master/examples/hedging.py

mimarob

Hi, this is cool.

Can someone explain the or tx.data[0] < 100:
in namecoin.py?

Comparisions between string and numeric: In python the numeric types comes first.

So it seems this will allow all non-occupied strings and also all non-occupied numericals below 100

Why is this? Are there some differences to CLL that I am unaware of?

mids106

Actually all keys and values are integers in the range 0 ... 2^256-1. If you want to store a string, it would first need to be converted to an integer. (The current version of cll-sim is cheating by just allowing you to use strings directly).

The check that the argument tx.data[0] is above 100 (the contract will stop otherwise), is so that you won't accidentally overwrite the contract etherscript code by storing a low value key.

mids106

Implemented support for the block.account_balance pseudo function as requested by @caktux

Small code sample:
https://github.com/jorisbontje/cll-sim/blob/master/examples/fountain.py

mimarob

Took me a while to digest this, seems ethereum has abandoned the Harvard architecture :-)