From ee00f736cc3b2ef753e99ca8de99d16f01a9cd51 Mon Sep 17 00:00:00 2001
From: Ryan Leavengood <leavengood@gmail.com>
Date: Sun, 16 Nov 2014 16:57:57 -0500
Subject: [PATCH] Add a CurrencyCount type with GrandTotal method

This hold totals in different currencies (currently expected to just be
USD and EUR), and GrandTotal provides a total in USD given a
conversion rate from EUR to USD.
---
 summary.go      |  8 ++++++++
 summary_test.go | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 summary.go
 create mode 100644 summary_test.go

diff --git a/summary.go b/summary.go
new file mode 100644
index 0000000..660eec3
--- /dev/null
+++ b/summary.go
@@ -0,0 +1,8 @@
+package main
+
+// Use a map because of multiple currencies
+type CurrencyCount map[string]float32
+
+func (c CurrencyCount) GrandTotal(eurToUsdRate float32) float32 {
+	return c["USD"] + c["EUR"]*eurToUsdRate
+}
diff --git a/summary_test.go b/summary_test.go
new file mode 100644
index 0000000..322d5a3
--- /dev/null
+++ b/summary_test.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+//==============================================================================
+// CurrencyCount.GrandTotal
+//==============================================================================
+
+const eurToUsdRate = 1.25
+
+func TestGrandTotalWithEmptyMap(t *testing.T) {
+	cc := make(CurrencyCount)
+
+	assert.Equal(t, 0, cc.GrandTotal(eurToUsdRate))
+}
+
+func TestGrandTotalWithJustUSD(t *testing.T) {
+	cc := CurrencyCount{
+		"USD": 34.56,
+	}
+
+	assert.Equal(t, 34.56, cc.GrandTotal(eurToUsdRate))
+}
+
+func TestGrandTotalWithJustUSDAndEUR(t *testing.T) {
+	cc := CurrencyCount{
+		"USD": 34.56,
+		"EUR": 10.00,
+	}
+
+	assert.Equal(t, 47.06, cc.GrandTotal(eurToUsdRate))
+}
+
+//==============================================================================