repCalc.js

#!/usr/bin/env node

var assert = require("assert");

// note: btc.total and btc.balance in BTC, not satoshis!
function calculateRepPercentage(btc, eth, exchangeRate) {
  return (eth.balance*exchangeRate + btc.balance) / (eth.total*exchangeRate + btc.total);
}

var test = function (t) {
  assert(calculateRepPercentage(t.btc, t.eth, t.exchangeRate), t.repPercentage);
};

test({
  btc: { total: 10, balance: 10 },
  eth: { total: 0, balance: 0 },
  exchangeRate: 1,
  repPercentage: 1
});
test({
  btc: { total: 0, balance: 0 },
  eth: { total: 10, balance: 10 },
  exchangeRate: 1,
  repPercentage: 1
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 0, balance: 0 },
  exchangeRate: 1,
  repPercentage: 0.5
});
test({
  btc: { total: 0, balance: 0 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 1,
  repPercentage: 0.5
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 1,
  repPercentage: 0.5
});
test({
  btc: { total: 10, balance: 0 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 1,
  repPercentage: 0.25
});
test({
  btc: { total: 10, balance: 0 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 1,
  repPercentage: 0.25
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 10, balance: 0 },
  exchangeRate: 1,
  repPercentage: 0.25
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 0.5,
  repPercentage: 0.5
});
test({
  btc: { total: 10, balance: 0 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 0.5,
  repPercentage: 1/6
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 10, balance: 0 },
  exchangeRate: 0.5,
  repPercentage: 1/3
});
test({
  btc: { total: 10, balance: 0 },
  eth: { total: 10, balance: 2.5 },
  exchangeRate: 0.5,
  repPercentage: 1/12
});
test({
  btc: { total: 10, balance: 2.5 },
  eth: { total: 10, balance: 0 },
  exchangeRate: 0.5,
  repPercentage: 1/6
});
test({
  btc: { total: 10, balance: 2.5 },
  eth: { total: 10, balance: 5 },
  exchangeRate: 0.5,
  repPercentage: 1/3
});
test({
  btc: { total: 10, balance: 5 },
  eth: { total: 10, balance: 2.5 },
  exchangeRate: 0.5,
  repPercentage: 5/12
});