Added sort_test.go

Makefile

@@ -1,2 +1,3 @@
 test:
-	go test github.com/kellegous/underpants/mux
+	go test github.com/kellegous/underpants/mux \
+		github.com/kellegous/underpants/util

util/sort_test.go

@@ -0,0 +1,30 @@
+package util
+
+import (
+	"sort"
+	"testing"
+)
+
+func TestWithInts(t *testing.T) {
+	v := []int{100, 101, 99, 98, 102}
+	Sort(len(v),
+		func(i, j int) bool {
+			return v[i] < v[j]
+		},
+		func(i, j int) {
+			v[i], v[j] = v[j], v[i]
+		})
+
+	if !sort.IntsAreSorted(v) {
+		t.Errorf("%v not sorted.", v)
+	}
+}
+
+func TestEmpty(t *testing.T) {
+	Sort(0,
+		func(i, j int) bool {
+			return false
+		},
+		func(i, j int) {
+		})
+}