[CH-5425] Fix apns-expiration request header logic (#9) (#237)

Co-authored-by: Zijin Li <zijin.li@braze.com>

client.go

@@ -227,7 +227,7 @@ func setHeaders(r *http.Request, n *Notification) {
 	if n.Priority > 0 {
 		r.Header.Set("apns-priority", strconv.Itoa(n.Priority))
 	}
-	if !n.Expiration.IsZero() {
+	if n.Expiration.After(time.Unix(0, 0)) {
 		r.Header.Set("apns-expiration", strconv.FormatInt(n.Expiration.Unix(), 10))
 	}
 	if n.PushType != "" {

client_test.go

@@ -245,6 +245,25 @@ func TestHeaders(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestExpirationHeader(t *testing.T) {
+	n := mockNotification()
+	n.ApnsID = "84DB694F-464F-49BD-960A-D6DB028335C9"
+	n.CollapseID = "game1.start.identifier"
+	n.Topic = "com.testapp"
+	n.Priority = 10
+	n.Expiration = time.Unix(0, 0)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, n.ApnsID, r.Header.Get("apns-id"))
+		assert.Equal(t, n.CollapseID, r.Header.Get("apns-collapse-id"))
+		assert.Equal(t, "10", r.Header.Get("apns-priority"))
+		assert.Equal(t, n.Topic, r.Header.Get("apns-topic"))
+		assert.Equal(t, "", r.Header.Get("apns-expiration"))
+	}))
+	defer server.Close()
+	_, err := mockClient(server.URL).Push(n)
+	assert.NoError(t, err)
+}
+
 func TestPushTypeAlertHeader(t *testing.T) {
 	n := mockNotification()
 	n.PushType = apns.PushTypeAlert