Make fiat balance test use new Trader API

Leave out the trading part for now since nobody is using this feature in
production.

test/unit/traderFiatBalanceTest.js

@@ -0,0 +1,48 @@
+'use strict';
+
+var assert = require('chai').assert;
+var Trader = require('../../lib/trader.js');
+var PostgresqlInterface = require('../../lib/protocol/db/postgresql_interface.js');
+
+var db = 'psql://lamassu:lamassu@localhost/lamassu-test';
+var psqlInterface = new PostgresqlInterface(db);
+
+var RATE = 100;
+var CURRENCY = 'USD';
+var SATOSHI_FACTOR = Math.pow(10, 8);
+var LOW_BALANCE_MARGIN = 1.2;
+var COMMISSION = 1.1;
+
+var settings = {
+  currency: CURRENCY,
+  lowBalanceMargin: LOW_BALANCE_MARGIN,
+  commission: COMMISSION
+};
+
+describe('trader/fiatBalance', function() {
+  it('should calculate balance correctly with transfer exchange only', function() {
+    var trader = new Trader(db);
+    trader.configure({
+      exchanges: {
+        plugins: {
+          current: {
+            transfer: 'blockchain',
+            ticker: 'bitpay'
+          },
+          settings: { blockchain: {}, bitpay: {} }
+        },
+        settings: settings
+      }
+    });
+
+    // We have 2 bitcoins, want to trade 1 bitcoin for 100 fiat
+    trader.balance = {
+      transferBalance: 2 * SATOSHI_FACTOR,
+      tradeBalance: null
+    };
+    trader.rates[CURRENCY] = { rate: RATE };
+
+    var balance = trader.fiatBalance(1 * SATOSHI_FACTOR, 100);
+    assert.equal(balance, (100 / LOW_BALANCE_MARGIN) * COMMISSION);
+  });
+});