Extract Reverse func

index.go

@@ -139,11 +139,7 @@ func (h *indexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	indexPage.Me = sess.Me
 
 	if len(moments) > 0 {
-		a := moments
+		Reverse(moments)
-		for i := len(a)/2 - 1; i >= 0; i-- {
-			opp := len(a) - 1 - i
-			a[i], a[opp] = a[opp], a[i]
-		}
 		lastMoment := moments[0]
 		indexPage.LastMomentSeconds = lastMoment.Time.Unix()
 	}

util.go

@@ -13,3 +13,12 @@ func RandStringBytes(n int) string {
 	}
 	return string(b)
 }
+
+func Reverse(moments []Moment) {
+	a := moments
+
+	for i := len(a)/2 - 1; i >= 0; i-- {
+		opp := len(a) - 1 - i
+		a[i], a[opp] = a[opp], a[i]
+	}
+}

util_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestReverse(t *testing.T) {
+	moments := []Moment{
+		{Key: "2018-01-01", Memo: "test", Time: time.Now()},
+		{Key: "2018-01-02", Memo: "test2", Time: time.Now()},
+		{Key: "2018-01-03", Memo: "test3", Time: time.Now()},
+		{Key: "2018-01-04", Memo: "test4", Time: time.Now()},
+	}
+
+	Reverse(moments)
+
+	if moments[0].Key != "2018-01-04" {
+		t.Errorf("wrong 1st key %q != %q", moments[0].Key, "2018-01-04")
+	}
+	if moments[1].Key != "2018-01-03" {
+		t.Errorf("wrong 2nd key %q != %q", moments[1].Key, "2018-01-03")
+	}
+	if moments[2].Key != "2018-01-02" {
+		t.Errorf("wrong 3rd key %q != %q", moments[2].Key, "2018-01-02")
+	}
+	if moments[3].Key != "2018-01-01" {
+		t.Errorf("wrong 4th key %q != %q", moments[3].Key, "2018-01-01")
+	}
+}