Adding Duration ptr helper. (#519)

* Adding Time and Duration ptr helpers.

* use do duration.

* nit picky reviwers get nit picky comments.

ptr/ptr.go

@@ -16,6 +16,8 @@ limitations under the License.
 
 package ptr
 
+import "time"
+
 // Int32 is a helper for turning integers into pointers for use in
 // API types that want *int32.
 func Int32(i int32) *int32 {
@@ -39,3 +41,9 @@ func Bool(b bool) *bool {
 func String(s string) *string {
 	return &s
 }
+
+// Duration is a helper for turning time.Duration into pointers for use in
+// API types that want *time.Duration.
+func Duration(t time.Duration) *time.Duration {
+	return &t
+}

ptr/ptr_test.go

@@ -16,7 +16,10 @@ limitations under the License.
 
 package ptr
 
-import "testing"
+import (
+	"testing"
+	"time"
+)
 
 func TestInt32(t *testing.T) {
 	want := int32(55)
@@ -49,3 +52,19 @@ func TestString(t *testing.T) {
 		t.Errorf("String() = &%v, wanted %v", *gotPtr, want)
 	}
 }
+
+func TestDuration(t *testing.T) {
+	want := 42 * time.Second
+	gotPtr := Duration(want)
+	if want != *gotPtr {
+		t.Errorf("Duration() = &%v, wanted %v", *gotPtr, want)
+	}
+}
+
+func TestDurationWithConst(t *testing.T) {
+	const want = 42 * time.Second
+	gotPtr := Duration(want)
+	if want != *gotPtr {
+		t.Errorf("Duration() = &%v, wanted %v", *gotPtr, want)
+	}
+}