diff --git a/test/gatt_client/gatt_client.c b/test/gatt_client/gatt_client.c
index 5ae5363a1..e25177d2c 100644
--- a/test/gatt_client/gatt_client.c
+++ b/test/gatt_client/gatt_client.c
@@ -20,9 +20,17 @@
 #include "hci.h"
 #include "ble_client.h"
 
-static bd_addr_t test_device_addr = {0x61, 0x48, 0x80, 0xe6, 0xa1, 0x71};
+static bd_addr_t test_device_addr = {0x34, 0xb1, 0xf7, 0xd1, 0x77, 0x9b};
+static le_peripheral_t test_device;
+
+static uint8_t advertisement_received;
+static uint8_t connected;
 
 void mock_simulate_hci_state_working();
+void mock_simulate_command_complete(const hci_cmd_t *cmd);
+void mock_simulate_scan_response();
+void mock_simulate_connected();
+void mock_simulate_exchange_mtu();
 
 void CHECK_EQUAL_ARRAY(uint8_t * expected, uint8_t * actual, int size){
 	int i;
@@ -33,31 +41,35 @@ void CHECK_EQUAL_ARRAY(uint8_t * expected, uint8_t * actual, int size){
 
 static void verify_advertisement(ad_event_t * e){
     CHECK_EQUAL(0, e->event_type);
- 	CHECK_EQUAL(1, e->address_type);
-	CHECK_EQUAL(183, e->rssi);
+ 	CHECK_EQUAL(0, e->address_type);
+	CHECK_EQUAL(188, e->rssi);
 	CHECK_EQUAL(3, e->length);
 	CHECK_EQUAL_ARRAY((uint8_t *)test_device_addr, (uint8_t *)e->address, 6);
 }
 
-uint8_t advertisement_received;
-
 static void handle_le_central_event(le_central_event_t * event){
 	switch(event->type){
 		case GATT_ADVERTISEMENT:
 			advertisement_received = 1;
 			verify_advertisement((ad_event_t *) event);
 			break;
+		case GATT_CONNECTION_COMPLETE:
+			printf("GATT_CONNECTION_COMPLETE\n");
+			connected = 1;
+			break;
 		default:
+			printf("handle_le_central_event");
 			break;
 	}
 }
 
-
 TEST_GROUP(GATTClient){
 	void setup(){
 		advertisement_received = 0;
+		connected = 0;
 		le_central_init();
 		le_central_register_handler(handle_le_central_event);
+		// le_central_register_packet_handler(handle_hci_event);
 		mock_simulate_hci_state_working();
 	}
 };
@@ -65,9 +77,18 @@ TEST_GROUP(GATTClient){
 
 TEST(GATTClient, TestScanning){
 	le_central_start_scan();
+	mock_simulate_command_complete(&hci_le_set_scan_enable);
+	mock_simulate_scan_response();
 	CHECK(advertisement_received);
 }
 
+TEST(GATTClient, TestConnecting){
+	le_central_connect(&test_device, 1, test_device_addr);
+	mock_simulate_connected();
+	mock_simulate_exchange_mtu();
+	CHECK(connected);
+}
+
 
 int main (int argc, const char * argv[]){
     return CommandLineTestRunner::RunAllTests(argc, argv);
diff --git a/test/gatt_client/mock.c b/test/gatt_client/mock.c
index f0b59a391..a0908891c 100644
--- a/test/gatt_client/mock.c
+++ b/test/gatt_client/mock.c
@@ -12,8 +12,8 @@
 static btstack_packet_handler_t att_packet_handler;
 static void (*gatt_central_packet_handler) (void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) = NULL;
 
-static uint8_t  l2cap_stack_buffer[20];
-static uint16_t max_l2cap_data_packet_length = 20;
+static const uint16_t max_mtu = 23;
+static uint8_t  l2cap_stack_buffer[max_mtu];
 
 void mock_simulate_command_complete(const hci_cmd_t *cmd){
 	uint8_t packet[] = {HCI_EVENT_COMMAND_COMPLETE, 4, 1, cmd->opcode & 0xff, cmd->opcode >> 8, 0};
@@ -25,11 +25,23 @@ void mock_simulate_hci_state_working(){
 	gatt_central_packet_handler(NULL, HCI_EVENT_PACKET, NULL, (uint8_t *)&packet, 3);
 }
 
-void mock_simulate_scan_response(){
-	uint8_t packet[] = {0x3E, 0x0F, 0x02, 0x01, 0x00, 0x01, 0x71, 0xA1, 0xE6, 0x80, 0x48, 0x61, 0x03, 0x02, 0x01, 0x1A, 0xB7};
+void mock_simulate_connected(){
+	uint8_t packet[] = {0x3E, 0x13, 0x01, 0x00, 0x40, 0x00, 0x00, 0x00, 0x9B, 0x77, 0xD1, 0xF7, 0xB1, 0x34, 0x50, 0x00, 0x00, 0x00, 0xD0, 0x07, 0x05};
 	gatt_central_packet_handler(NULL, HCI_EVENT_PACKET, NULL, (uint8_t *)&packet, sizeof(packet));
 }
 
+
+void mock_simulate_scan_response(){
+	uint8_t packet[] = {0x3E, 0x0F, 0x02, 0x01, 0x00, 0x00, 0x9B, 0x77, 0xD1, 0xF7, 0xB1, 0x34, 0x03, 0x02, 0x01, 0x05, 0xBC};
+	gatt_central_packet_handler(NULL, HCI_EVENT_PACKET, NULL, (uint8_t *)&packet, sizeof(packet));
+}
+
+void mock_simulate_exchange_mtu(){
+	printf("mock_simulate_exchange_mtu\n");
+	uint8_t packet[] = {0x03, 0x17, 0x00};
+	att_packet_handler(ATT_DATA_PACKET, 0x40, (uint8_t *)&packet, sizeof(packet));
+}
+
 int hci_can_send_packet_now_using_packet_buffer(uint8_t packet_type){
 	return 1;
 }
@@ -39,25 +51,19 @@ int  l2cap_can_send_connectionless_packet_now(void){
 }
 
 int hci_send_cmd(const hci_cmd_t *cmd, ...){
-	// printf("hci_send_cmd \n");	
-	
-	if (cmd == &hci_le_set_scan_enable){
-		mock_simulate_command_complete(cmd);
-		mock_simulate_scan_response();
-	}
+	printf("hci_send_cmd opcode 0x%02x\n", cmd->opcode);	
 	return 0;
 }
 
 
 uint8_t *l2cap_get_outgoing_buffer(void){
-	printf("l2cap_get_outgoing_buffer \n");
+	printf("l2cap_get_outgoing_buffer\n");
 	return (uint8_t *)&l2cap_stack_buffer; // 8 bytes
 }
 
-
 uint16_t l2cap_max_mtu(void){
-    printf("l2cap_max_mtu \n");
-    return max_l2cap_data_packet_length;
+	printf("l2cap_max_mtu\n");
+    return max_mtu;
 }
 
 
@@ -69,18 +75,13 @@ void l2cap_register_packet_handler(void (*handler)(void * connection, uint8_t pa
 	gatt_central_packet_handler = handler;
 }
 
-int hci_reserve_packet_buffer(void){
-	printf("hci_reserve_packet_buffer \n");
+int l2cap_reserve_packet_buffer(void){
+	printf("l2cap_reserve_packet_buffer\n");
 	return 1;
 }
 
-int l2cap_reserve_packet_buffer(void){
-	printf("l2cap_reserve_packet_buffer \n");
-    return hci_reserve_packet_buffer();
-}
-
 int l2cap_send_prepared_connectionless(uint16_t handle, uint16_t cid, uint16_t len){
-	printf("l2cap_send_prepared_connectionless \n");
+	printf("l2cap_send_prepared_connectionless\n");
 	return 0;
 }