###### tags: `tests` # Solidity Mid Test ### Test Description The purpose of this test is to: - see how you perform research to solve new tasks - communicate with me your research findings and QUESTIONS **Requirements** - Ask questions - Report progress after every time you work on it - Try to finish as many tasks as possible during your time constraint. contact @sirpy on telegram ### Tasks 1. GoodDolalr protocol is deployed also on the Fuse (fuse.io) blockchain. write a solidity function "modifier" that allows only the current "Fuse Validators" to execute the functions which the modifier is applied to. Research how to get the current list of validators **on-chain.** so you can use it in your modifier. 2. Write a solidity method that receives a Block Header + blockhash from an evm blockchain of your choice (ethereum, fuse, binance etc..) and verifies that the hash(BlockHeader) == blockhash A typical block header would look like: ``` BlockHeader { parent_hash: bytes32 timestamp: uint256, number: uint256, author: address, transactions_root: bytes32, uncles_hash: bytes32, extra_data: bytes, state_root: bytes32, receipts_root: bytes32, log_bloom: bytes, gas_used: uint256, gas_limit: uint256, difficulty: uint256, mixHash:bytes32, nonce:uint256 } ``` 3. Is there a difference in gas efficiency between the two ways to return the person age? if so why? ``` Person persons[]; ... A. Person memory p = persons[i] return p.age B. return persons[i].age ``` 4. write a solidity calcMaxAmount(uint16 maxImpact, address uniswapv2pair) given a "max price impact percentage in 16bits" and "uniswap v2 pair" the method should calcaulte what is the max amount that you can swap from pair.token0 to pair.token1 given the max price impact percentage constraint
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React/React Native - Research/Integration

Our app needs to upload some files to IPFS. We want to use Pinata pinning API. Uploads should be performed from the client side directly (without passing through our NodeJS backend server) It have an HTTP api documented on the Pinata homepage, and NodeJS SDK There's no browser SDK but we could upload to the Pinata API endpoint directly using fetch() or axios client. A complete example with axios usage could be found inside its Node SDK source Goals and objectives You need to implement a simple proof on concept app: A simple UI with preview image (show some placeholder if no image uploaded) and "Upload..." button

1/27/2022
React Native Part 3 - Research

The application is using react-native v0.65.1. It builds under NodeJS 14.17.6 and OpenJDK 8. The new version of some library we're using was requiring to set compile/target SDK versions to 31. After we did it, the build have started failing with the following output: > Task :react-native-device-info:compileDebugJavaWithJavac FAILED Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0. Use '--warning-mode all' to show the individual deprecation warnings.

1/24/2022
Solidity Advanced Test

The purpose of the test is to check how you learn and research new material. But also how do you communicate with me to help you and guide you, so it is perfectly fine and expected that you ask the right questions when you are stuck, or to confirm that you are on the right track. Good Luck Read the "Fuse Bridge" specifications here: (You DO NOT need to implement it) https://github.com/GoodDollar/Bounties/issues/9 Answer the following The first condition for the smart contract is that only "Fuse Validators" can write to it. Research how can you get the current list of validators on-chain. Write a solidity or javascript method that receives a Block Header from an evm blockchain of your choice (ethereum, fuse, binance etc..) and correctly calculates the Block Hash using the data from the block header

12/16/2021
Junior Solidity Test 2

Task 1 - Contract to save signed blockheaders The purpose of this contract is to enable a fixed set of trusted validators to submit blockhashes from another blockchain. the contract will hold a mapping of blockhash -> BlockData a mapping of blockhash -> SignedBlock contract will be initialized with a list of validators addresses BlockHeader { parent_hash: bytes32 timestamp: uint256,

12/12/2021
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