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Enable Stablecoin Loan Kit

Enable is a open source stablecoin loan kit that enables anyone to deploy a fullly functional peer-to-peer stablecoin loan with the following features:

  1. Immutable record of loan agreement and automatic tracking of repayments and defaults
  2. Out-of-the-box handling of crowdfunding and fractional ownership through loan shares
  3. Automatic routing of repayments to fractional owners

We built Enable with the vision to expand opportunity to emerging market borrowers through access to credit, to fund value-creating activities like education and starting a business.

Design Philosophy

The Enable stablecoin loan kit is standalone, and designed with minimum viable complexity in mind.

It is heavily inspired by the OpenZeppelin Crowdfund contracts and Dharma's loan contracts.

Components

The Crowdloan functionality has been decomposed into the following categories:

  • Crowdloan: Track state of crowdfund, collect funds from lenders, and issue debt tokens. Once the funding is complete the borrower can withdraw funds. If the loan fails to get fully funded, lenders can withdraw their contribution.

  • RepaymentRouter: Handle repayments, and track withdrawal allowances for debt token holders.

  • TermsContract: Get information about the terms of the loan and it's current status.

Future Plans

We believe parts of this project could morph into generic standards useful to theEthereum community. We'll be expanding, modularizing, and genercizing as appropriate when the initial implementation is finished.

Developer Instructions

CI Pipeline

https://circleci.com/gh/enabledao/enable-contracts

zos workflow for local development

We use ZeppelinOS to develop, deploy and operate the Enable loan kit packages. The ZeppelinOS Documentation is a good start.

Setup

  1. Run npm install to install all zeppelinOS related dependencies
  2. Run ganache-cli (or ganache-cli --deterministic) to run a local blockchain
  3. Create your own .env file based on .env.sample. These are the process.env variables that will be used for deployment / application. As of Aug 2019 this is the Infura API key and mnemonic"

Deploy to ganache development network

For background: read Publishing an EVM package.

  1. zos publish --network development. This publishes the project's app, package and provider. This updates the zos config file with "app.address" field that is needed for tests to run.
  2. zos push --network development. This deploys the contracts in the project. This has the same effect as running zos create on every contract. See Quickstart for context.

Deploy to ethereum and development networks mainnet, ropsten, kovan, ganche

  1. Run npm run deploy:contracts -- --network kovan from bash; change the network to the desired network

Deploy Miscellaneous contracts to any truffle configures network mainnet, ropsten, kovan, ganche

Run npx truffle exec scripts/deploy/paymentToken-deploy.js --network development --{args} from node/terminal; change the network to the desired network

Avaialble scripts

  1. scripts/deploy/paymentToken-deploy.js: Arguments --name, --symbol, --decimals.

npx truffle exec scripts/deploy/paymentToken-deploy.js --network development --name 'EnableDao Dai' --symbol EDAI --decimals 18

  1. scripts/deploy/tokenFaucet-deploy.js: No arguments.

npx truffle exec scripts/deploy/tokenFaucet-deploy.js --network development

Running tests

  1. npm run test. This also runs zos push, which updates the contracts with the latest vrsions

Upgrading contracts

For background: read Upgrading contracts

  1. zos upgrade <contract name> or zos upgrade --all based on contract changed. This should upgrade the contracts.

Editor setup

We use ESLint and Prettier to format our code. Please make sure you have the following setting turned on in VSCode (or equivalent editor).

editor.formatOnSave: true

Test solidity coverage

We use Solidity Coverage.

$(npm bin)/solidity-coverage

Troubleshooting

Common errors

Cannot read property address

// Example
> npm t
TypeError: Cannot read property 'address' of undefined

This happens because zos needs contracts to be published. To resolve, run:

zos publish
zos publish --network development

"Appears to be git repo or submodule" during npm install

This is usually because of the websocket module which web3 depends on. Remove all .git submodules using the command below

# Finds all instances of .git folders in node_modules
find ./node_modules -name ".git"

# Deletes them
find ./node_modules -name ".git" -delete

Terminology

Persons

  1. Lender: lends to a loan
  2. Borrower: person who loan is disbursed to

Nouns

  1. Loan Shares: fractional ownership in a loan
  2. Funding Goal: this is same as principalRequested from the borrower's point of view
  3. Total Crowdfunded: this is the amount raised in the crowdfund
  4. Principal Requested: the loan amount the borrower is requesting for
  5. Principal Disbursed: the amount
  6. Donations: "unauthorized" native ERC-20 transfers to smart contract

Actions

  1. Fund: lenders fund a loan

Stages and Outcomes

We need a set of (Mutually Exclusive, Collectively Exhaustive)[https://www.caseinterview.com/mece] stages and outcomes, that are used for our require checks.

Some possible scenarios we will need to 'describe':

Scenario 1: Crowdfund has ended, but borrower does not withdraw funds. If they do not start loan within a certain period of time (e.g. 48 hours), lenders should be able to refund.

Stage: crowdfund ended Crowdfund Outcome: no outcome yet -> crowdfund refunded

Scenario 2: Crowdfund has ended, and borrower decides they do not want the loan and wants to refund the money.

Stage: crowdfund ended Crowdfund Outcome: crowdfund refunded

Scenario 3: During crowdfund, borrower decides to pause the crowdfund. The crowdloan:fund should be suspended.

Stage: crowdfund started Crowdfund Outcome: no outcome yet -> crowdfund paused

Stages

These steps are sequential. require statements can use < of <= to test for stages

  1. crowdfund notStarted
  2. crowdfund started
  3. crowdfund ended (either early end by borrower, or hit goal)
  4. loan started and in repayment cycle (this can mean that it's in default)
  5. completed (i.e. either fully paid back or written off)

Crowdfund Outcomes (pertains to outcome of crowdfund)

  1. no outcome yet (in progress, or pending acceptance)
  2. crowdfund paused (not implemented)
  3. crowdfund ended
  4. crowdfund refunded (i.e. borrower rejects the crowdfund, returns money)
  5. crowdfund accepted (i.e. borrower starts the loan)

Loan Outcomes (pertains to outcome of loan)

  1. On time (not fully paid back yet)
  2. Late 30, 60, 90, 180 (number of days it's behind in loans)
  3. Fully paid back
  4. Written off (default)