From 013df9350b9488420b904204e4138b42dfb299db Mon Sep 17 00:00:00 2001
From: Arthur Burkart <artburkart@gmail.com>
Date: Fri, 20 Oct 2017 17:54:23 -0400
Subject: [PATCH] hashcode: "Strings" function for hashing slices of strings

---
 helper/hashcode/hashcode.go      | 13 +++++++++++++
 helper/hashcode/hashcode_test.go | 11 +++++++++++
 2 files changed, 24 insertions(+)

diff --git a/helper/hashcode/hashcode.go b/helper/hashcode/hashcode.go
index 64d8263e6..6ccc52318 100644
--- a/helper/hashcode/hashcode.go
+++ b/helper/hashcode/hashcode.go
@@ -1,6 +1,8 @@
 package hashcode
 
 import (
+	"bytes"
+	"fmt"
 	"hash/crc32"
 )
 
@@ -20,3 +22,14 @@ func String(s string) int {
 	// v == MinInt
 	return 0
 }
+
+// Strings hashes a list of strings to a unique hashcode.
+func Strings(strings []string) string {
+	var buf bytes.Buffer
+
+	for _, s := range strings {
+		buf.WriteString(fmt.Sprintf("%s-", s))
+	}
+
+	return fmt.Sprintf("%d", String(buf.String()))
+}
diff --git a/helper/hashcode/hashcode_test.go b/helper/hashcode/hashcode_test.go
index 1b521823f..4b90431ba 100644
--- a/helper/hashcode/hashcode_test.go
+++ b/helper/hashcode/hashcode_test.go
@@ -15,6 +15,17 @@ func TestString(t *testing.T) {
 	}
 }
 
+func TestStrings(t *testing.T) {
+	v := []string{"hello", ",", "world"}
+	expected := Strings(v)
+	for i := 0; i < 100; i++ {
+		actual := Strings(v)
+		if actual != expected {
+			t.Fatalf("bad: %#v\n\t%#v", actual, expected)
+		}
+	}
+}
+
 func TestString_positiveIndex(t *testing.T) {
 	// "2338615298" hashes to uint32(2147483648) which is math.MinInt32
 	ips := []string{"192.168.1.3", "192.168.1.5", "2338615298"}