add currency conversion method

Reviewers: luis

Reviewed By: luis

Subscribers: ben

Differential Revision: https://phabricator.bitgo.com/D5952

Author: Arik Sosman

package.json

@@ -1,6 +1,6 @@
 {
   "name": "bitgo",
-  "version": "3.4.5",
+  "version": "3.4.6",
   "description": "BitGo Javascript SDK",
   "main": "./src/index.js",
   "keywords": [

src/v2/baseCoin.js

@@ -1,4 +1,5 @@
 var Keychains;
+var BigNumber = require('bignumber.js');
 var PendingApprovals;
 var Wallet;
 var Wallets;
@@ -74,6 +75,16 @@ BaseCoin.prototype.initializeCoin = function(coin) {
   coinInstance.call(this);
 };
 
+/**
+ * Convert a currency amount represented in base units (satoshi, wei, atoms, drops) to big units (btc, eth, rmg, xrp)
+ * @param baseUnits
+ */
+BaseCoin.prototype.baseUnitsToBigUnits = function(baseUnits) {
+  const dividend = this.getBaseFactor();
+  const bigNumber = new BigNumber(baseUnits).dividedBy(dividend);
+  return bigNumber.toFormat();
+};
+
 /**
  * If a coin needs to add additional parameters to the wallet generation, it does it in this method
  * @param walletParams

test/v2/baseCoin.js

@@ -0,0 +1,38 @@
+//
+// Tests for Wallets
+//
+
+var assert = require('assert');
+var should = require('should');
+
+var common = require('../../src/common');
+var TestV2BitGo = require('../lib/test_bitgo');
+
+describe('V2 Base Coin:', function() {
+  var bitgo;
+  var wallets;
+  var keychains;
+  var basecoin;
+
+  before(function() {
+    // TODO: replace dev with test
+    bitgo = new TestV2BitGo({ env: 'test' });
+    bitgo.initializeTestVars();
+    basecoin = bitgo.coin('teth');
+    wallets = basecoin.wallets();
+    keychains = basecoin.keychains();
+  });
+
+  describe('Currenncy conversion', function() {
+    it('should convert wei amounts to ETH', function() {
+      // 1 wei
+      basecoin.baseUnitsToBigUnits(1).should.equal('0.000000000000000001');
+      // 100 wei
+      basecoin.baseUnitsToBigUnits(100).should.equal('0.0000000000000001');
+      // 1 ETH
+      basecoin.baseUnitsToBigUnits('1000000000000000000').should.equal('1');
+      // others
+      basecoin.baseUnitsToBigUnits('1000000010000000000').should.equal('1.00000001');
+    });
+  });
+});