add priority on message

message.go

@@ -1,5 +1,12 @@
 package gcm
 
+const (
+	//HighPriority represent high value for priority field
+	HighPriority = "high"
+	//NormalPriority represent normal value for priority field
+	NormalPriority = "normal"
+)
+
 // Message is used by the application server to send a message to
 // the GCM server. See the documentation for GCM Architectural
 // Overview for more information:
@@ -12,6 +19,7 @@ type Message struct {
 	TimeToLive            int                    `json:"time_to_live,omitempty"`
 	RestrictedPackageName string                 `json:"restricted_package_name,omitempty"`
 	DryRun                bool                   `json:"dry_run,omitempty"`
+	Priority              string                 `json:"priority,omitempty"`
 }
 
 // NewMessage returns a new Message with the specified payload

sender.go

@@ -206,6 +206,8 @@ func checkMessage(msg *Message) error {
 	} else if msg.TimeToLive < 0 || 2419200 < msg.TimeToLive {
 		return errors.New("the message's TimeToLive field must be an integer " +
 			"between 0 and 2419200 (4 weeks)")
+	} else if len(msg.Priority) > 0 && msg.Priority != HighPriority && msg.Priority != NormalPriority {
+		return errors.New("the message priority value must be normal or high")
 	}
 	return nil
 }

sender_test.go

@@ -75,6 +75,9 @@ func TestSendNoRetryInvalidMessage(t *testing.T) {
 	if _, err := sender.SendNoRetry(&Message{RegistrationIDs: []string{"1"}, TimeToLive: 2419201}); err == nil {
 		t.Fatal("test should fail when message TimeToLive field is greater than 2419200")
 	}
+	if _, err := sender.SendNoRetry(&Message{RegistrationIDs: []string{"1"}, Priority: "invalid"}); err == nil {
+		t.Fatal("test should fail when priority value is not high or normal")
+	}
 }
 
 func TestSendInvalidMessage(t *testing.T) {
@@ -99,6 +102,9 @@ func TestSendInvalidMessage(t *testing.T) {
 	if _, err := sender.Send(&Message{RegistrationIDs: []string{"1"}, TimeToLive: 2419201}, 0); err == nil {
 		t.Fatal("test should fail when message TimeToLive field is greater than 2419200")
 	}
+	if _, err := sender.Send(&Message{RegistrationIDs: []string{"1"}, Priority: "invalid"}, 0); err == nil {
+		t.Fatal("test should fail when priority value is not high or normal")
+	}
 }
 
 func TestSendNoRetrySuccess(t *testing.T) {
@@ -160,3 +166,14 @@ func TestSendOneRetryNonrecoverableFailure(t *testing.T) {
 		t.Fatal("send should fail after one retry")
 	}
 }
+
+func TestSendWithPrioritySuccess(t *testing.T) {
+	server := startTestServer(t, &testResponse{Response: &Response{}})
+	defer server.Close()
+	sender := &Sender{ApiKey: "test"}
+	msg := NewMessage(map[string]interface{}{"key": "value"}, "1")
+	msg.Priority = HighPriority
+	if _, err := sender.SendNoRetry(msg); err != nil {
+		t.Fatalf("test failed with error: %s", err)
+	}
+}