Truffle challenges

These examples are part of my guide The best way to become Ethereum Developer in 2018

and 30/30 challenge on polish ethereum programming FB group (members write one contract a day to improve Solidity skills).

First 11 Solidity challenges without Truffle are here

Try to write a contract yourself before checking the code in the repo!

Challenges

12_string_converter

• create function to convert string to bytes32
• add Solidity test for that function

13_route_manager

• contract must store a list of bus stops
• each bus stop has id, name and coordinates (i.e czn1, PKS Cieszyn, 10.123222, 33.212345)
• owner should be able to add new stops
• contract must have test coverage

14_route_manager_test

• add Solidity tests
• add JavaScript tests

15_shared_wallet

• contract has one owner
• owner can add and remove managers
• manager can withdraw all the funds
• contract has a payable fallback function to receive transfers

16_multisig_wallet

• create a multi signature wallet
• transfers can only be done when 3 managers sign the transaction

17_crowdsale

• create mintable coin (use Open Zeppelin)
• create simple crowdsale (use Open Zeppelin)
• set opening and closing time
• set rate and wallet address

18_roles_management

• create contract which inherites from Ownable (Open Zeppelin)
• contract must have a list of managers
• owner can add/update/remove manager
• owner is a manager too
• add modifier onlyManager

19_the_dao_attack

• add very simplified The DAO contract (deposit, withdraw)
• add attacker contract

20_lpg_price

• get LPG price using Oraclize API

21_random_oraclize

• get random number using Oraclize API

22_raffle_oraclize

• users can join raffle once
• owner can't participate
• winner is picked using RNG from Oraclize

23_ipfs_oraclize

• add a simple json file to ipfs
• use oraclize to read that file
• store the result of one json attribute in a string variable

24_election

• create one contract per election, providing a short name and address for each candidate.
• creator of the contract gives the right to vote to each address individually
• each voter can vote once
• voter can not vote on himself

25_faucet

• add fallback to accept the payment
• add withdraw method which allows anyone to get maximum 1 ether
• log both amounts (paid, transferred) using events

26_swarm_oraclize

• add text file to Swarm public gateway (https://swarm-gateways.net)
• read that file in the contract through Oraclize API

27_dapp_pet_shop

• build dapp based on https://truffleframework.com/tutorials/pet-shop
• allow owner to cancel adoption
• write a test for cancelling adoption (TDD)
• add cancelling function to the smart contract

28_infura_deployment

• add settings for ropsten deployment using infura

29_tic_tac_toe

• add basic tic tac toe for 2 players
• 3x3 board
• no AI

Other challenges

• Plain Solidity: 1-12
• Web3 deploy challenge: 30

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