Merge branch 'i1746-BalanceBasedOnPending' into AddBalanceController

2 files changed, 149 insertions, 0 deletions

diff --git a/app/scripts/lib/pending-balance-calculator.js b/app/scripts/lib/pending-balance-calculator.js
new file mode 100644
index 000000000..474ed3261
--- /dev/null
+++ b/app/scripts/lib/pending-balance-calculator.js
@@ -0,0 +1,51 @@
+const BN = require('ethereumjs-util').BN
+const normalize = require('eth-sig-util').normalize
+
+class PendingBalanceCalculator {
+
+  // Must be initialized with two functions:
+  // getBalance => Returns a promise of a BN of the current balance in Wei
+  // getPendingTransactions => Returns an array of TxMeta Objects,
+  // which have txParams properties, which include value, gasPrice, and gas,
+  // all in a base=16 hex format.
+  constructor ({ getBalance, getPendingTransactions }) {
+    this.getPendingTransactions = getPendingTransactions
+    this.getNetworkBalance = getBalance
+  }
+
+  async getBalance() {
+    const results = await Promise.all([
+      this.getNetworkBalance(),
+      this.getPendingTransactions(),
+    ])
+
+    const balance = results[0]
+    const pending = results[1]
+
+    const pendingValue = pending.reduce((total, tx) => {
+      return total.add(this.valueFor(tx))
+    }, new BN(0))
+
+    return `0x${balance.sub(pendingValue).toString(16)}`
+  }
+
+  valueFor (tx) {
+    const txValue = tx.txParams.value
+    const value = this.hexToBn(txValue)
+    const gasPrice = this.hexToBn(tx.txParams.gasPrice)
+
+    const gas = tx.txParams.gas
+    const gasLimit = tx.txParams.gasLimit
+    const gasLimitBn = this.hexToBn(gas || gasLimit)
+
+    const gasCost = gasPrice.mul(gasLimitBn)
+    return value.add(gasCost)
+  }
+
+  hexToBn (hex) {
+    return new BN(normalize(hex).substring(2), 16)
+  }
+
+}
+
+module.exports = PendingBalanceCalculator
diff --git a/test/unit/pending-balance-test.js b/test/unit/pending-balance-test.js
new file mode 100644
index 000000000..17be0306b
--- /dev/null
+++ b/test/unit/pending-balance-test.js
@@ -0,0 +1,98 @@
+const assert = require('assert')
+const PendingBalanceCalculator = require('../../app/scripts/lib/pending-balance-calculator')
+const MockTxGen = require('../lib/mock-tx-gen')
+const BN = require('ethereumjs-util').BN
+let providerResultStub = {}
+
+const zeroBn = new BN(0)
+const etherBn = new BN(String(1e18))
+const ether = '0x' + etherBn.toString(16)
+
+describe('PendingBalanceCalculator', function () {
+  let balanceCalculator
+
+  describe('#valueFor(tx)', function () {
+    it('returns a BN for a given tx value', function () {
+      const txGen = new MockTxGen()
+      pendingTxs = txGen.generate({
+        status: 'submitted',
+        txParams: {
+          value: ether,
+          gasPrice: '0x0',
+          gas: '0x0',
+        }
+      }, { count: 1 })
+
+      const balanceCalculator = generateBalanceCalcWith([], zeroBn)
+      const result = balanceCalculator.valueFor(pendingTxs[0])
+      assert.equal(result.toString(), etherBn.toString(), 'computes one ether')
+    })
+
+    it('calculates gas costs as well', function () {
+      const txGen = new MockTxGen()
+      pendingTxs = txGen.generate({
+        status: 'submitted',
+        txParams: {
+          value: '0x0',
+          gasPrice: '0x2',
+          gas: '0x3',
+        }
+      }, { count: 1 })
+
+      const balanceCalculator = generateBalanceCalcWith([], zeroBn)
+      const result = balanceCalculator.valueFor(pendingTxs[0])
+      assert.equal(result.toString(), '6', 'computes one ether')
+    })
+  })
+
+  describe('if you have no pending txs and one ether', function () {
+
+    beforeEach(function () {
+      balanceCalculator = generateBalanceCalcWith([], etherBn)
+    })
+
+    it('returns the network balance', async function () {
+      const result = await balanceCalculator.getBalance()
+      assert.equal(result, ether, `gave ${result} needed ${ether}`)
+    })
+  })
+
+  describe('if you have a one ether pending tx and one ether', function () {
+    beforeEach(function () {
+      const txGen = new MockTxGen()
+      pendingTxs = txGen.generate({
+        status: 'submitted',
+        txParams: {
+          value: ether,
+          gasPrice: '0x0',
+          gas: '0x0',
+        }
+      }, { count: 1 })
+
+      balanceCalculator = generateBalanceCalcWith(pendingTxs, etherBn)
+    })
+
+    it('returns the subtracted result', async function () {
+      const result = await balanceCalculator.getBalance()
+      assert.equal(result, '0x0', `gave ${result} needed '0x0'`)
+      return true
+    })
+
+  })
+})
+
+function generateBalanceCalcWith (transactions, providerStub = zeroBn) {
+  const getPendingTransactions = () => Promise.resolve(transactions)
+  const getBalance = () => Promise.resolve(providerStub)
+  providerResultStub.result = providerStub
+  const provider = {
+    sendAsync: (_, cb) => { cb(undefined, providerResultStub) },
+    _blockTracker: {
+      getCurrentBlock: () => '0x11b568',
+    },
+  }
+  return new PendingBalanceCalculator({
+    getBalance,
+    getPendingTransactions,
+  })
+}